Biogas Journal English Issue October 2015 by Fachverband Biogas e.V.

www.biogas.org

German Biogas Association | ZKZ 50073

Gas Journal

The trade magazine of the biogas sector

Status quo biomethane feeding in Germany P. 6

October_2015

Corrosion damage in biogas plants P. 14

english issue

Small mobile biogas plants for refugee camps P. 22

Including cou ntry reports fr om Denmark, Fra nce and Vietn am

English Issue

Biogas Journal | October_2015

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Editorial

Biogas Journalâ&#x20AC;&#x192; |â&#x20AC;&#x192; October_2015

Opportunities and risks for the all-rounder biogas Dear readers, The biogas technology has lost nothing of its fascination because it is so extremely versatile. It is applied in many areas and provides ingenious solutions to the most different problems. In most cases, it starts with a digestion substrate that is simply there, and reasonable use can only be made of it by converting it to biogas. Plants of this type feed on waste and secondary products from households, the industry or farms. Residual material is turned into fertiliser, the nutrients of which replace manmade fertiliser in the fields. More or less as a side effect, a versatile fuel is also produced. For example, energy for transport, heating and cooking or the production of electricity can be produced from it. So the technology is suitable for many different applications and there are only few standard biogas plants. This versatility is a boon and a bane at the same time. The biogas technology offers many solutions and for that very reason cannot be replicated easily, but must be adapted to the conditions of the site. This is a challenge for the planner as well as for the owner because biogas must be understood as a system. This requires passion as much as stamina because biogas knows no breaks; it operates 24 hours a day, seven days a week. Additional issues may occur during holidays or at night. The most important actors in the game, the microorganisms, are easily offended by mistakes of feeding and operation and therefore must be kept sweet. Whoever is open and ready to invest a measure of passion is rewarded with high yields and the great feeling to have produced energy and valuable fertiliser from waste. Most owners become completely compassionate at the latest when the gas starts rising from the substrate. When that happens, any remaining problems will be overcome and the project become a success story. However, when the equipment is a mismatch, the time for tending the plant

cannot be spared or the required know-how does not exist, the biogas plant will never operate at a profit. This is where the risks of the biogas technology lurk. Because the technology is so many-sided and offers so many opportunities, it is complex and requires know-how and intensive commitment to the issue. Mind you, you need not be a college graduate to operate a biogas plant, but interest and a measure of enthusiasm are indispensible. This is why the German Biogas Association focusses its work, including the English version of the Biogas Journal, increasingly on the international context to disseminate specialist know-how about the technological challenges and the safe and reliable operation of biogas plants. This is our contribution to making the abounding opportunities of the application of biogas technology a success and ensuring that the biogas concept, through its successes, becomes self-perpetuating. I hope you enjoy reading this issue of the Biogas Journal and find new and interesting points.

Sincerely yours,

Claudius da Costa Gomez Managing Director of the German Biogas Association

English Issue

Biogas Journal | October_2015

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Editor: Martin Bensmann German Biogas Association Phone: +49 54 09 9 06 94 26 e-mail: martin.bensmann@biogas.org Advertising management & Layout: bigbenreklamebureau GmbH An der Surheide 29 D-28870 Ottersberg-Fischerhude Phone: +49 42 93 890 89-0 Fax: +49 42 93 890 89-29 e-mail: info@bb-rb.de

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Publisher: German Biogas Association General Manager Dr. Claudius da Costa Gomez (Person responsible according to German press law) Andrea Horbelt (editorial support) Angerbrunnenstraße 12 D-85356 Freising Phone: +49 81 61 98 46 60 Fax: +49 81 61 98 46 70 e-mail: info@biogas.org Internet: www.biogas.org

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Printing: Druckhaus Fromm, Osnabrück Circulation: 3,000 The newspaper, and all articles contained within it, are protected by copyright. Articles with named authors represent the opinion of the author, which does not necessarily coincide with the position of the German Biogas Association. Reprinting, recording in databases, online services and the Internet, reproduction on data carriers such as CD-ROMs is only permitted after written agreement. Any articles received by the editor’s office assume agreement with complete or partial publication.

English Issue

Biogas Journal | October_2015

Editorial

3 Opportunities and risks for the all-rounder biogas Claudius da Costa Gomez Managing Director of the German Biogas Association

4 Imprint

Reports from germany

6 Fewer feeding plants By Dipl.-Ing. agr. (FH) Martin Bensmann

10 Small-size plants as additional income source By Dr. Stefan Rauh and Robert Wagner 14 Corrosion damage in biogas plants By Dipl.-Ing. · Dipl.-Journ. Martina Bräsel 18 Environmental compatibility with biogas as transport fuel By Thomas Gaul 19 Examples of natural gas-powered vehicles sold in Germany By Thomas Gaul 22 Small mobile biogas plants for refugee camps By Dipl.-Ing. · Dipl.-Journ. Martina Bräsel 26 “Turkey: interesting market with vulnerabilities” Interviewer: Dierk Jensen

Country reports

30 France: An ambitious change By Marie-Luise Schaller 34 Denmark: Boom-Boom-Slurry By Dierk Jensen 38 Vietnam: Potential: 10 billion cubic metres of biomethane By Klaus Sieg

natureOffice.com | DE-563-650410

print production

coverPhoto: by Dierk Jensen Photos: provided by VW, Martina Bräsel, Martin Egbert

carbon neutral

38 5

English Issue

Biogas Journal | October_2015

Biomethane

Fewer feeding plants Last year, when the EEG (The German Renewable Energy Sources Act) was revised, the biomethane treatment bonus was cancelled. We wanted to find out whether this aspect of the revised Act had an effect on the construction of new biomethane feeding plants. By Dipl.-Ing. agr. (FH) Martin Bensmann

total of 21 new biogas plants feeding biomethane in the natural gas grid started production last year, see Figure 2. That were eight plants less than in 2013. By the end of 2014, 164 plants fed biomethane into the German natural gas grid. The newly constructed raw gas treatment capacity was 20,950 standard cubic metres per hour last year (see Figure 1). The distribution of the total number of plants among the German states is as follows: ffLower Saxony: 30 (+2) ffSaxony Anhalt: 24 (+7) ffBavaria: 19 ffBrandenburg: 18 (+4) ffHesse: 13 (+1) ffNorth Rhine Westphalia: 13 (+3)

PHoto: Fotolia

ffMecklenburg-Western Pomerania: 11 (+1) ffSaxony: 10 ffBaden Wuerttemberg: 10 (+1) ffThuringia: 7 (+2) ffSleswig Holstein: 4 ffRhineland Palatinate: 2 ffBerlin, Saarland, Hamburg: 1 each As in the years before, most new capacities were added in the Eastern German states and in Lower Saxony. The smallest feeding plant built last year has a raw gas treatment capacity of 200 standard cubic metres per hour. The largest feeding plants completed last year can treat 1,400 standard cubic metres of raw gas an hour. The total raw gas treatment capacity added last year amounted to 20,950 standard cubic metres per hour, about 5,900 standard cubic metres less than in 2013. The raw gas treatment capacity throughout Germany rose to 171,215

standard cubic metres per hour by the end of 2014. Of the feeding plants completed in 2014 one plant digests biogenic residues only. Another plant operates on renewable raw materials as well as on biological residues. All other plants feed on renewable primary products only. When looking at the type of gas treatment, the following frequency is obtained for 2014: ffAmine scrubber: 3 ffPressurised water scrubber: 9 ffMembrane separation: 2 ffPressure swing adsorption: 3 ffChemical/physical scrubbing: 2 ffOrganic/physical scrubbing: 1

The raw gas treatment method of one plant was not clear on press date. Taking an average annual operating time of roughly 8,000 hours, the 164 plants connected to the natural gas grid can process 1.369 billion cubic metres of raw biogas. Assuming an average methane concentration of 52 per cent in the raw biogas because most plants feed on renewable primary products, a total of 712 million cubic metres (2013: 625 million cubic metres) of biomethane can be fed into the German natural gas grid. This is equal to approximately 7.2 per cent of the natural gas extracted in Germany in 2014. The figure boils down to 0.9 per cent of the natural gas consumed last year. The present rate of production is sufficient to supply about 2.0 million German homes (each with a consumption of 3,500 kWh a year) with biomethane (258,395 homes more than in 2013).

Nearly 5 per cent less primary energy consumed

Preliminary statistics published by the Arbeitsgemeinschaft Energiebilanzen (AGEB) e.V. say that the primary energy consumption in Germany dropped by 4.7 per cent to 13,077 petajoules (PJ) last year, due to the warm weather. This is the lowest level since the German reunification. With the exception of the renewable sources, the reduced consumption embraced all energy sources more or less. According to AGEB figures, the consumption of natural gas dropped by almost 13 per cent to 2,674 PJ or 91.2 million tons of coal equivalents. This development was mainly due to the outdoor temperatures being distinctly higher during the heating season than the year before. The AGEB annual report continues: “With the

Rohgasaufbereitungs-‐ 1.000 kapazität in Nm3/h Kumuliert Biogas Journal | October_2015

2.150 3.150

4.635 7.785

28.250 36.035

19.830 55.865

32.350 88.215

35.200 123.415

26.850 20.950 150.265 171.215 English Issue

3/h in Germany, annual Table 1: Development ofDevelopment of the raw gas treatment capaci4y in m the raw gas treatment capacity in m3/h in Germany, annual increase since 2006 and cumulative increase since 2006 and cumula4ve

171,215

180.000 , 150,265

160.000 ,

, 140.000

123,415

120.000 , 100.000 ,

88,215

80.000 ,

55,865

, 60.000

36,035

40.000 , 20.000 ,

28,250 1,000

3,150 4,635

2,150

19,830

32,350

35,200

26,850

20,950

7,785

2006

2007

2008

2009

2010

2011

2012

2013

2014

Annual increase of the raw gas treatment capacity in m³/h

exception of renewable energy sources, the reduced consumption embraced all energy sources more or less. Of all fossil fuels, the consumption of natural gas dropped most

CumulaLve increase of the raw gas treatment capacity

dramatically by almost 13 per cent, mainly due to the weather. Coal also recorded a reduction by about 8 per cent. The fossil fuel following next was brown coal with a reduced

consumption close to 4 per cent and mineral oil with more a reduction of one per cent. The consumption of energy from renewable sources recorded a slight rise by 0.5 per cent

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English Issue

Biogas Journal | October_2015

Jahr Anzahl Anlagen

2006 2

2007 3

2008 7

2009 17

2010 19

Table 2: Development of the biomethane feeding plants in Germany, annual increase since 2006

2011 31

2012 35

2013 29

2014 21

Development of the biomethane feeding plants in Germany, annual increase since 2006 35

35 31

29 25 20

19 17

15 10

2006

2007

2008

2009

2010

2011

2012

2013

2014

Source: German Biogas Associa@on

in 2014 and with about 11 per cent of the total consumption closely follows coal and brown coal. This rise, which is modest compared with prior years, is mainly the result of the drop in hydropower consumption (-10.9 per cent) and in biogenic solid fuels (-9.1 per cent). In contrast to that, photovoltaics rose by almost 13 per cent, wind power by more than 8 per cent, biogas by about 6 per cent and biogenic municipal waste by 5 per cent.

Natural gas consumption and domestic extraction have dropped In 2014, the consumption of natural gas in Germany dropped by 12.6 per cent to 823 billion kilowatt hours (calorific value). The consumption of natural gas by power and heating plants for general supply dropped distinctly by 13 per cent. This is because more electricity was produced from renewable sources on the one hand, and the power consumption generally dropped in Germany on the other hand. The supply of natural gas in Germany dropped by 11 per cent to 1.041 billion kilowatt hours in comparison with the year before. One tenth of that volume came from domestic sources, 90 per cent were imported. Domestic extraction was 13.6 per cent lower and dropped to 99.5 billion kilowatt hours. The supply from German sources remains stable at 10 per cent due to the general reduction in consumption. Natural gas imports dropped by 11.1 per cent. Russia remains the Number One supplier. The share of Rus-

sian natural gas increased marginally from 37 per cent (2013) to 38 per cent. Norway also supplied a little more; natural gas from that country accounted for 21 per cent in 2013 and went up to 22 per cent in the year under report. The Dutch share remained stable at 26 per cent. The remaining 4 per cent were imported from Denmark, Britain and other countries (2013: 6 per cent). So, totally about two thirds of the natural gas consumption in Germany came from Western European sources. The natural gas exports by German suppliers were 10 per cent lower.” The market analysis shows: The changed general political situation under the revised EEG legislation did not fail to produce the desired effect. Besides, in view of the political imponderabilities, banks are increasingly averse to financing large feeding projects and investors are less motivated to shoulder large investment amounts. Moreover, the biomethane cogeneration market is saturated and less attractive financially in comparison with natural gas-fired cogeneration units.

Biomethane would be good for GHG reduction in transport The mobility sector could be an important outlet for excess biomethane, particularly on the background of the greenhouse gas reduction targets, which replaced the biogenic fuel quota at the beginning of this year. However, biomethane from primary raw materials will not stand a chance here for cost reasons. Biomethane from waste digesting

plants might fare better in this respect. The reason why biomethane does not figure high as a fuel is not a lack of available vehicles but the poor marketing by the car industry in this area and the fact that the GHG reduction quota of 3.5 per cent is too low. So merely 21 new biomethane feeding plants were built in 2014. This is definitely a kind of market slump. The fact that the number is not lower is explained by the long lead time for planning and the enormous planning cost, so that once a project has advanced to a certain stage it simply must be pursued to completion. The question now is how many new plants will be built in 2015? We found out during our search that at least one new plant went on stream and started injecting biomethane into the natural gas grid in February. Another one was to follow in May. As of end-April, some 15 new biomethane plants were reported as connecting to the natural gas system during 2015. Hence, most probably about 20 new feeding plants will be added to the present stock and the level of 2014 may be maintained. The development in 2016 is difficult to forecast. Very likely that fewer new plants will be built unless the general political conditions change. Author Dipl.-Ing. agr. (FH) Martin Bensmann Editor of the Biogas Journal German Biogas Association Phone +49 (0)54 09 90 69 426 e-mail: martin.bensmann@biogas.org

English Issue

Biogas Journal | October_2015

Optimized mixing power and efficiency for every substrate

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English Issue

Biogas Journal | October_2015

Photo: Novatech GmbH

Small-size plants as additional income source

The revision of the EEG Act in 2014 was a major setback in the construction of new biogas plants. Only small plants feeding on manure record a number of new additions worth a mention. The reason is that, depending on the operating configuration, these plants can make a sizable contribution to the earnings of a farm. By Dr. Stefan Rauh and Robert Wagner

he legal framework is decisive for the profitability of a project. On the income side, the EEG 2014 sets the electricity remuneration for small size manure-fed biogas plants at 23.53 ct/kWh, whereas on the cost side the requirements of the minimum dwell time and the storage capacity, respectively play a decisive role. Three different plant concepts will be described in the following (Table 1). The simplest concept is a biogas plant feeding on slurry only (plant concept 1 “slurry”). At first sight, these plants have a lot of advantages: ffShort dwell time (about 30 days). ffNo additional digested product store (agree with the competent authority beforehand). ffLower power input, about 5 per cent.

(plant concept 2, “slurry/manure”) and renewable primary products (NawaRo). As these plants produce additional liquid products from digestion, new and normally gas-tight stores must be constructed. The available manure stores will continue in use. Whether the integration of an available manure store as store for digested products is technically possible and under approval of the law depends on the requirements of the applicable plant regulations (AwSV) because liquid manure-fed plants must satisfy less strict requirements than digested product stores for biogas plants. The following calculations assume that available slurry plants can continue in use. Plant concept 3 (“slurry/manure/renewable primary”) complies with the requirement of 150 days in the gas-tight system by a new, gas-tight digester and the digested product store.

ffSimple stirrer technology possible. ffNo solid substrate feeding equipment required. ffLow raw material cost. In operating the biogas plant, the owner is definitely bound to using liquid manure, particularly as far as the constructional implications are concerned. Solid inputs cannot readily be digested. The other concepts considered below digest, in addition to slurry also cattle manure

High volume means high investment cost Table 1 clearly shows that energy-rich energy crops reduce the vessel volume distinctly with corresponding consequences for the investment cost per kilowatt-hour (see Table 2). Despite the feeding of solid substrate and the required stirring units, the slurry/manure/renewable primary plant has the lowest cost per installed kilowatt of electricity output (7,100 euros/kW). Compared with re-

English Issue

Biogas Journal | October_2015

Effects of divergent investment costs and higher substrate costs on the economic efficiency

Powerful Products

70,000 Gain basic case 60,000

Gain with low investment costs Gain wiht high investment costs

50,000

Gain with high substrate costs

Gain [€]

40,000

... for Biogas plants.

30,000

20,000

10,000

0 Plant concept 1

Plant concept 2

Plant concept 3

-10,000

Explanatory notes: low/high investment costs: +/- 20% at the investment high substrate costs: +€3/t with slurry, dung and renewable raw material Source: FvB and Carmen 2015

newable primary plants in the medium and high output brackets, most of which were built in the period of the EEG 2009, prices are high. For example, a plant with 30 kW output requires investments of a quarter million and one of 75 kW output of half a million euros. Looking at operating cost, plants feeding on farm manure have a clear advantage because the substrates are available normally. The calculations assume that the supply cost of slurry is 0.50 euros for each cubic metre and 1.00 euro per ton of farm manure. Farm manure is produced at the place of the biogas plant. Plant concept 3 assumes that the energy crops are delivered to the digester at a price of 40 euros for each ton of fresh mass. Even if less than 20 per cent by weight of energy plants are fed as substrate, the substrate cost rises to a little less than 30,000 euros. This is equal to about 25 per cent of the annual cost. In slurry-only plants the substrate cost amounts to under seven per cent.

Small-size manure plants earn additional income Under the assumed general conditions, all three plant concepts add to the income of the farm (see Table 2) with overall returns of more than 10 per cent. Whereas the profit from the 30 kW plant is moderate because of the small size of the plant, the profit from the two larger plants clearly helps to stabilise the

overall operating income. The possible use of heat from cogeneration is not included in the calculation. The reason is the wide fluctuation, depending on the construction and the substrates. Generally, small biogas plants feeding mainly on slurry consume relatively much heat. This is due, for one, to the fact that the water in the slurry must also be heated and, for another, that the ratio between surface and volume of small vessels is less favourable. If heat can be used outside the biogas plant, the level of process heat consumption should be kept low already at the design stage. The slurry should be supplied to the biogas plant fresh while it is warm. Heat recovery by heat exchangers at the transfer point to the digestion residue store reduces the process consumption further. Heat loss should also be avoided at the solid substrate feeding point. Basically, digesters with an insulated concrete roof need less heat than a digester with a plastic store or inflated dome.

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Concrete design should be calculated on site It will be understood that the positive earnings situation illustrated here depends largely on the assumptions made. As described above, two decisive parameters are the investment and the substrate cost. For that reason, the effect of variations of these parameters on the earnings will be discussed in the following. For example, if the available

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English Issue

Biogas Journal | October_2015

Table 1: Description of the examined plant concepts Plant concept 1 “slurry”

Plant concept 2 “slurry / dung”

Plant concept 3 “slurry / dung / renew. raw material”

Installed capacity [kW] Substrate requirement [m³ bzw t]

6,400

9,300

2,100

- cattle dung

- cattle manure

1,100

1,400

- renew. raw material

650

260

470

230

Animal/land requirements [quantity respectively ha] - cattle-GV - renew. raw material

150 days retention time

yes

Fermenter volume [m³]

500

1,400

800

Slurry tank existing [m³]

3,200

5,000

2,000

2,500

1,000

Retention time fermenter [d]

Retention time gas-tight room [d]

137

158

Digestate storage expansion (gas-tight) [m³]

Explanatory notes: kW = kilowatt, m³ = cubic metre, t = tons, ha = hectare, GV = animal unit © FvB and CARMEN 2015

slurry storage vessels cannot be used for technical reasons or according to the applicable legislation, the investment cost will rise dramatically. So the effects of 20 per cent higher investment cost are investigated. The consequences of lower investment costs are also looked into. The latter may be the case when a farm must set up new vessels because more animals are kept and therefore the cost

of building the vessels can be posted to the stock keeping account. Moreover, often a higher price must be paid for the substrates when the animals on the farm do not produce enough manure and additional amounts must be obtained from other farms. In such cases, the transport cost adds to the overall expenses framework. The substrate cost was increased by three euros for each ton of fresh weight in the breakdown.

The result of these variations is illustrated in the figure. A more cost-effective (green column) or more expensive (red column) construction reduces the profit of the small plant by about 6,000 euros. The difference is 13,000 euros for the two 75 kW plants. In the case of the slurry/manure/renewable primary plant the higher investment cost reduces the profit to just over 10,000 euros. So potential builders may reconsider whether the pro-

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English Issue

Biogas Journal | October_2015

Table 2: Economic efficiency of the examined plant concepts Plant concept 1 “slurry”

Plant concept 2 “slurry / dung”

Plant concept 3 “slurry /dung / renew. raw material”

240,000

590,000

530,000

Amount invested [e/kW]

8,000

7,900

7,100

Investment costs [e/a]

23,800

54,400

52,100

Operating costs [e/a]

19,200

39,600

63,900

- Substrate costs

3,200

5,700

28,700

Sum of costs [e/a]

43,000

94,000

116,000

EEG-proceeds [e/a]

56,500

142,000

141,500

Gain [e/a]

13,500

48,000

25,500

Installed capacity [kW] Amount invested [e]

Beetcutter Type: BB-1250 / BB-2500

Explanatory notes: kW = kilowatt, a = year © FvB and CARMEN 2015

posed concept is optimum for the development of the plant operation. Plants feeding only on slurry or manure are particularly sensitive to higher cost of these substrates (orange column). For example, in case of plant concept 2 the profit drops by 32,000 euros when three euros more must be paid for each ton of slurry or manure bought from outside. In the case of the small plant, this effect will convert the profit into a net loss. Consequently, a slurry-only 30 kW plant can only be recommended when sufficient substrate is available on the farm.

Use of waste requires a detailed check Considering the enormous importance of the substrate cost farmers might think about adding waste or residues to the available slurry. The EEG 2014 permits that. In addition to 80 per cent by weight of slurry up to 20 per cent by weight of waste may be added. As a result of that, however, such biogas plants would usually be classed as waste-fed plants, which can add substantially to the procurement cost. Besides, additional requirements under approval and waste legislation must be considered. Usually, these additional requirements make the use of waste as co-substrate financially less attractive – despite the cheaper substrate. Conclusion: Generally, small biogas plants feeding only on slurry can operate at a profit. It should be noted however that a 30 kW plant requires slurry from 260 livestock units. An interesting financial proposition is also the additional digestion of solid substrate (ma-

nure, energy plants) in biogas plants. The operating result can improve when part of the slurry is replaced by manure. All substrate concepts discussed above are very sensitive to the investment and substrate cost. So each case should be considered on its merits and discussed with a competent adviser. More detailed information on the calculations presented here is available in the publication of Biogas Forum Bayern: Wagner, R.; Glötzl, M.; Rauh, S.; Schober, J.; Haberstetter, S. and Geitner, H. (2015): Wirtschaftlichkeit von Kleinbiogasanlagen auf Güllebasis. In: Biogas Forum Bayern Nr. V – 21/2015, Hrsg. ALB Bayern e.V., www. biogas-forum-bayern.de/publikationen/ Wirtschaftlichkeit_von_Kleinbiogasanlagen_auf_Gullebasis.pdf

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Silage scraper Type: TIGER

Authors Dr. Stefan Rauh Managing director German Biogas Association

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substrate processing

e-mail: info@biogas.org Robert Wagner Biogas and Mobility Department Head C.A.R.M.E.N e.V. Schulgasse 18 ∙ 94315 Straubing

English Issue

Biogas Journal | October_2015

Corrosion damage in biogas plants Corrosion is expensive: In Germany alone, this undesired phenomenon causes loss worth about 100 billion euros every year. Corrosion is also a problem that is often underrated in biogas plants. By Dipl.-Ing. · Dipl.-Journ. Martina Bräsel

he project which researchers of the Fachhochschule Südwestfalen in Iserlohn have taken on will continue until early next year and will answer the question how biogas plants can be protected for a long term by more corrosion resistant materials. To this end the researchers have collected damage samples from operating corn silage plants for three years and examined them in the laboratory. “The causes of corrosion in a biogas plant are many,” Dr. Ralf Feser, head of the university laboratory for corrosion protection technology in Iserlohn, explains. The term “corrosion” subsumes all impairing reactions on non-metals and metals with their environment caused by chemical, electrochemical or microbiological processes. In practice, several causes are often involved in a corrosive process. To find out which corrosion processes are typical of biogas plants and to simulate them in the laboratory, Dr. Feser and his team took the different damage cases together, cut open agitators, pipelines and shafts and examined the damage pattern under the microscope. “We were able to simulate the corrosive stress and the operating conditions in such a way that the prac-

tical processes were replicated and accelerated,” team member Alexander Krebs explains. The advantage: Overlapping processes such as abrasion and erosion can be eliminated in the research lab; this makes it possible to study the corrosion reaction alone.

Corrosion of microbial origin Practically any materials – in addition to metals also polymers, glass and ceramics – can be attacked and changed by microorganisms. The term used in this case is microbially induced corrosion (MIC). Experts estimate that 20 per cent of the cost due to corrosion is caused by MIC. “This type of corrosion is virtually omnipresent in biogas plants,” Dr. Feser is sure. The agents causing most damage are sulfate reducing bacteria (SRB). The researchers found that unalloyed steels, in particular, were prone to MIC; but they also found this type of damage on corrosion-resistant steel and concrete floors. “We found corrosive attack in the liquid and the gas phases,” Feser adds. The desulfurisation of biogas plants was another major factor, because the typical hydrogen sulfide concentrations in the digestion of slurry, biogenic residue

Figure 1: Left: Broken edge of the immersion pocket, black cover layer with pitting and crevice corrosion in circumferential direction. Right: Cross section with crevice corrosion at the transition between the liquid and the gas phase, about 1.3 mm deep

English Issue

Biogas Journal | October_2015

Figure 2: Left: Micrograph with surface corrosion and pitting at the outer surface, 200x magnification. Right: Total image of the micrograph with pitting, about 5.5 mm deep, etched with 3 % alcoholic nitric acid

and food waste range from 2,000 to 5,000 ppm. Before biogas can be used in a cogeneration unit, that undesired substance must be eliminated from the biogas as far as possible. “Therefore, in biological desulfurisation, some air oxygen is injected directly into the gas zone of the digester,” Feser explains. As a consequence of this, the aerobic microorganisms growing on the wall of the vessel and the liquid surface metabolise. Hydrogen sulfide is converted to elemental sulfur and sulfate; besides, sulfuric acid is formed in the aqueous atmosphere. “The sulfuric acid can attack the materials in the gas phase of the digester and at the phase interface between gas and liquid,” the expert explains. Even high-grade steel such as 1.4571 cannot withstand that stress permanently. Another risk factor was chemical desulfurisa-

tion by iron salts. “In this process, iron salt (for example, FeCl2) is added by the solids dosing unit or directly into the digester with the substrate,” Alexander Krebs illustrates the approach. In this way the hydrogen sulfide forms as sparingly soluble iron sulfide directly in the liquid phase of the digester. The problem: Under certain conditions chlorine-induced corrosion damage to metal materials can occur when air oxygen is present in an aqueous environment. “These conditions are often found in the substrate pipelines or mixing vessels of a biogas plant,” Krebs explained.

Corrosion in the mixing vessel To develop recommendations for the use of materials in biogas plants, the researchers developed typical damage

English Issue

Biogas Journal | October_2015

Figure 3: Digester surface with extensive pitting and crevice corrosion as well as surface corrosive attack, corrosion resistant steel grade 1.4571. Right: Micrograph, crevice corrosion at the surface, 50x magnification

cases from practical cases. These included corrosion in the mixing vessel. In that vessel, substrate and fresh manure are homogenised by stirring and are then pumped into the main digester of the biogas plant. “The damage occurred at the immersion pocket of the mixing vessel,” Alexander Krebs explains. A temperature sensor was installed in the immersion pocket, which was about 1.5 meters long and made of corrosion-resistant steel (1.4301). It had been installed vertically through the roof of the vessel, near the edge so that it was immersed into the liquid in the mixing vessel. After six years of operation the immersion pocket was broken at the side facing the roof of the vessel. The broken piece had been deformed by about 30 degrees along the longitudinal axis on one side, the fracture extending vertically. A black cover layer running around the full circumference of the extensive pitting and crevice corrosion was found below the broken edge (see Figure 1). “This also formed the level line below which the pocket was immersed completely into the liquid in the mixing vessel,” Dr. Feser added. Corrosion attack had been strongest there. “The examination showed that the owner of the biogas plant had used iron chloride for de-

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sulfurisation,” Feser explained. As a consequence, the component had been exposed to the attack of the corrosive chloride ions in addition to the mechanical alternating stress of stirring. “The chloride ions caused pitting of the material, mainly along the level line,” the expert adds. Deep superficial crevices had formed there. The added mechanical stress had then resulted in corrosion fatigue and caused the failure of the component.

Corrosion at the agitator After only three years of operation the shaft of a paddle agitator suffered corrosive attack. The shaft, which consisted of unalloyed steel with organic coating, was supported horizontally on two trusses between the vessel wall and the centre support of the digester. “The paddles of the agitator had been mounted on the shaft in fixing sleeves at right angles,” Alexander Krebs explains. There was a gap of about 10 millimetres between two adjacent fixing sleeves. At that point, the digester fluid was in direct contact with the surface of the shaft. The owner found crevice corrosion during an inspection, see Figure 2. The shaft was replaced as a precaution. “There had been several shaft breaks on identical agitators of the

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Biogas Journal | October_2015

same biogas plant,” Dr. Feser remembers. “In this case, we presume the damage had been caused by microbially induced corrosion (MIC),” he says. The anaerobic conditions there and the fairly strong corrosive attack (~2 mm/a) suggested that. The higher shear stress due to the agitation in the gap area destroyed the coating, whereupon the unprotected steel surface was in direct contact with the fluid in the digester. Corrosion may then have been caused by metabolic products (sulfides, hydrogen sulfide) of the microorganisms or directly by the microorganisms.

Corrosion at the digester wall of high-alloy steel The corrosion damage occurred after six years of operation at the inside wall of a digester. The vessel material in the area of the liquid phase was 1.4301; higher grade material 1.4571 had been used for the gas space. The damage was located in the gas space above the line that separated the liquid from the gas phase in the digester. “After we had removed the sulfur from the wall we found corrosion attack along the black covering layer,” Krebs from the lab team says. The team detected pitting and crevice corrosion and an extended area of corrosion (see Figure 3). The yellowish sulfur deposit had formed as a result of the biological desulfurisation. This happens when the sulfuroxidising bacteria metabolise the hydrogen sulfide to sulfur and sulfate. This occurs in the presence of between 0.4 and 3 per cent by volume of oxygen in the gas space of the digester. “All the inside wall in the gas space of the digester was affected by corrosion and had to be replaced completely,” Krebs says. The area below the level line (liquid phase) was completely intact. That corrosion damage was also the result of microorganisms. In the presence of oxygen, which started the biological desulfurisation, the hydrogen sulfide was converted to sulfur and sulfate. “Sulfuric acid which attacks the surface of the material directly can form in an aqueous environment,” Dr. Feser explains. Thus corrosion starts and is encouraged in the presence of oxygen. Conclusion: “Corrosive sulfuric acid which forms during biological desulfurisation can be the cause of corrosive damage in the gas phase of a biogas plant; the acid also attacks high-alloy steel,” Dr. Feser explains. The iron oxide which is added to the diges-

tion process as a desulfurisation agent accelerates corrosion particularly in parts of the plant (for example, substrate pipelines and mixing vessels) made of non-corrosive steel. However, corrosion also attacks materials in the liquid phase of the digester, i.e., the aerobic zone of the biogas plant such as, for example, agitator shafts of unalloyed steel. In that case microbially induced corrosion was a main cause. “The corrosion resistance of the metal parts of a biogas plant can be improved by choosing the most suitable materials,” Dr. Feser states in conclusion. It was better to use high-alloy steels with more chromium. However, it was also important that the steel contained sufficient molybdenum, which improved the resistance to pitting and crevice corrosion of the materials. “Besides, oxygen should not be present in the gas zone of the biogas plant,” Feser is sure. So, it would be better to choose a different desulfurisation such as, for example, external biological desulfurisation. All final results of the project will be presented at a public status seminar of the Gesellschaft für Korrosionsschutz e.V. in Frankfurt on 25 November 2015. The other project partners such as the Bavarian Landesanstalt für Landwirtschaft (Freising), the Official Material Testing Institution of the Free Hanseatic City of Bremen and the APMA Services GmbH (Saarlouis) will also present their results.

Author Dipl.-Ing. · Dipl.-Journ. Martina Bräsel Freelance journalist Science and Journalism Hohlgraben 27 · 71701 Schwieberdingen Phone + 49 (0) 71 50 92 18 772-2 e-mail: braesel@mb-saj.de www.mb-saj.d

English Issue

Biogas Journal | October_2015

Environmental compatibility with biogas as transport fuel Vehicles running on natural gas can make an important contribution to a successful fundamental change in energy policy in the transport sector. Their contribution to saving of CO2 is particularly big when vehicles are powered by upgraded biogas (biomethane), which is no problem for vehicles of any brand. By Thomas Gaul

very important sector in this respect is goods traffic where CO2-emissions are still increasing. The technology of the vehicles has meanwhile entered the maturity stage. The number of models marketed by the automotive manufacturers has been expanded. To date, 40 models of cars and commercial vehicles are in the market. More models have been announced for the next five

Number of natural gas filling stations and fleet of vehicles 1999-2015 Existing natural gas filling stations Filling stations

Fleet of gas vehicles Vehicles ,

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Source: Kraftfahrt-Bundesamt, erdags mobil, March 2015

years. Biomethane is an environmentally friendly fuel – for the small city car as much as for the heavy truck. The number of filling stations has also increased. By now, over 900 stations operate in Germany alone. The number of stations selling biomethane is also increasing; most sell it as an admixture. The market share of the fuel that is also known as biogenic natural gas has gone up to 23 per cent. This is five times the share it had in 2011. In addition to protecting the climate, biomethane as a fuel is also a powerful money saver. Unfortunately, the finan-

cial advantage cannot readily be seen at the filling station. The reason is the different pricing at filling stations. Natural gas as fuel is sold by kilogram and not by litre which makes comparisons with other fuels difficult. As natural gas contains more energy than diesel or petrol, it is difficult to compare on a litre-price basis. Uniform pricing is a European demand but has not been translated into German law so far. The same applies to the continuation of the tax privilege for natural gas as fuel. The privilege is fixed until 2018. So far, no legislative steps have been taken for the years after that. As it is, biomethane is a fuel of practical value with even more potential for the future: Produced from residual sources and renewable primary materials grown in the fields, it is available on a permanent basis. Filling stations in Germany sell biomethane as an admixture in different concentrations. The environment is a winner, definitely: When 20 per cent are admixed, the CO2 emission is 30 per cent lower than that of carburetor fuel; vehicles running on natural gas only save 97 per cent of the carbon dioxide emissions, a study by the German Energy Agency (dena) says. A new method (“Power-to-Gas”) even converts wind energy to fuel gas. The required CO2 is provided by a nearby biogas plant. It is an undoubted fact that CO2 emissions in the transport sector must be reduced. A study by the German Federal Economics Ministry believes that natural gas-powered vehicles will make up as much as nine per cent of all motor vehicles by 2030, depending on the oil price development and the vehicle class. Researchers believe natural gas-powered vehicles will have a higher market share than electric vehicles.

Author Thomas Gaul Freelance journalist Im Wehrfeld 19a 30989 Gehrden Phone +49 (0)172 512 71 71 e-mail: gaul-gehrden@t-online.de

English Issue

Biogas Journal | October_2015

Overview (not complete) of natural gas-powered vehicles sold in the German market at present. Technical specifications are taken from the manufacturers` literature. The calculation of the average fuel consumption is based on an average price of 1.10 euros a kilogram.

Opel Com

Photos: provided by manufacturers

Audi A3 Sportback g-tron Output 81 kW/110 HP Maximum speed 197 km/h Cubic capacity 1,395 cm³ Natural gas filling volume 14.4 kg Petrol filling volume 50 l Natural gas consumption 3.3 kg/100 km Fuel cost per 100 km 3.63 euros Reach with natural gas 420 km Total reach 1,380 km Emissions/CO2 92 g/km Boot capacity 280 l Efficiency class A+

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ech r the Cz ered ca w o and p ! s eco up ral ga rst natu ith VW’s fi oww e p e n th s li a s ral g ds in a tu TEC wa n a n G ta o e s ig It arketed r to th 013. daCit ewcome odaCitigo is m arly in 2 The Ško n e a d e s h a c k un top led Š maker la coFuelStart&S gas-fue natural MiiE e . h ’s ls T T e . A SE mod cars all-size legance E m s d n d a re n e io e, Ambit as Activ 8 HP 50 kW/6 m/h Output d 164 k e e m sp Maximu city 999 cm³ g apa me 11 k Cubic c ing volu ll fi s a g m Natural g volume 10 l g/100 k llin on 2.9 k ti p m Petrol fi u s s gas con .19 euro Natural 00 km 3 1 r m e k p 0 t 8 Fuel cos natural gas 3 ith Reach w 600 km ach Total re 79 g/km ns/CO 2 io s is Em 13 l 2 pacity Boot ca

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The Opel Com bo 1.4 CNG ecoFLEX Turb closed box ve o is availabl rsion and as e as an open a car or light natural gas or commercial tank is mou vehicle. As th nt ed underfloor, th 4.6 cubic met e e inside volu res (dependi me of 3.8 to ng on the whe makes the fu el ba se ll boot capa ) is not restri city usable cted. This about one to without rest n of payload riction and ca n be transpor (long wheelba up to ted. With a fil se 22.1 kg) na l of 16.15 kg tural gas an 88 kW/120 H d a 22-litre pe P NATURAL G trol tank the AS Combo ca The Opel Com n cover up to bo CO -emis 625 kilometre sion is given 2 s. at 134 g/km . Output 88 kW /120 HP Maximum sp eed 172 km/h Cubic capaci ty 1,368 cm³ Natural gas filling volum e 16.15 - 22 Petrol filling .1 kg volume 22 l Natural gas consumption 4.9 kg/100 km Fuel cost per 100 km 5.39 euros Reach with na tural gas 32 5 km Total reach 62 5 km Emissions/C O 134 g/km Boot capacity 2 720 - 3,200 l Efficiency cl ass B

VW eco up! This new small-size car from Volkswagen has been availab le with a natural gas-powered engine since early 2013. Blue Motion tech nology is standard with this model. The engine needs 2.9 kilogra ms of natural gas for 100 kilometres which corresponds to 79 grams CO -emission per kilometre. With an output of 68 HP, the car’s maximum 2 speed is 164 km/h. The VW eco up! is ava ilable as take up!, move up! and high up! models. The city car won the Goldenes Lenkrad 2011 awa rd already shortly after it was launched. Output 50kW/68 HP Maximum speed 164 km/h Cubic capacity 999 cm³ Natural gas filling volume 11 kg Petrol filling volume 10 l Natural gas consumption 2.9 kg/100 km Fuel consumption per 100 kilo meters 3.19 euros Reach with natural gas 380 km Total reach 600 km Emissions/CO 79 g/km 2 Boot capacity 213 l

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Škoda

Biogas Journal | October_2015

Octavia G-TEC

rs-powered car ma second natural ga e th is C a’s TE od GŠk is via r e ca The Škoda Octa Octavia mid-rang h car maker. The e by another atng ra red keted by this Czec we po sthe natural ga s nd pa ex d 1.4-liter turboan a er th bestsell C is equipped wi TE Gs via ta Oc e sides, it also save tractive model. Th rt-stop system. Be sta th n wi loo e sa gin as en t l en in the marke charged petro e energy. It has be ak br e th ng eri ov fuel by rec ce mid-2014. and estate car sin HP Output 81 kW/110 5 km/h 19 d ee sp Maximum 95 cm³ Cubic capacity 1,3 volume 15 kg Natural gas filling e 50 l lum vo Petrol filling km ption 3.5 kg/100 um ns co s ga Natural ros eu 5 3.8 km Fuel cost per 100 l gas 420 km Reach with natura km 60 1,3 Total reach g/km Emissions/CO2 94 ecified sp t no y cit pa ca Boot

The Fiat Doblò 1.4 T-Jet 16V Natural Power is now available in the fourth model generation. The car is designed for the needs of active families and comes with a multitude of functions for everyday use. A family van that has really the most spacious inside in its class and a large number of innovative safety and comfort features. The natural gas-powered car is equipped with a six-step gearbox as standard. The natural gas tank is installed under the floor, so there is no compromis e as to the interior space. The Fiat Doblò consumes 5.3 kg natural gas for 100 kilometres and emits 134 g/km CO2. The car’s reach is up to 324 kilom etres in natural gas mode and up to 621 kilometres when combined with the petrol tank. Output 88 kW/120 HP Maximum speed 172 km/h Cubic capacity 1,368 cm³ Natural gas filling volume 17.22 kg Petrol filling volume 22 l Natural gas consumption 5.3 kg/100 km Fuel cost per 100 km 5.83 euros Reach with natural gas 324 km Total reach 621 km Emissions/CO2 134 g/km Boot capacity 750 l Efficiency class B

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s ncy clas ar efficie . Basic h it w plies 2014 t since enz com . The edes-B in effec rc n e e ectively e p M b s m s re o a , h fr e n s h s a ic B cla , wh meth kilogram the 20 The new uro 6 standard ral gas and bio n e h w (156 ly eE on atu 115 kW A and th gine runs on n tre petrol tank de, the o m omen il s li e k a e er 100 tural g the 12 p a cally, th n s to s m In e. e . ra h d kilog switc auste kilometr system erely 4.4 7 grams per ly is exh p m p de s u o e s m m s ga gas consu n of 11 natural natural -seater a CO 2 emissio In e . v d fi e e v in pro HP) eng orresponds to been im car has is c . s e tr tres. Th e reach of the me , th 500 kilo Besides ar runs about c e alone th /156 HP 115 kW 00 km/h Output speed 2 cm³ m u im x Ma 1,991 g apacity me 20 k Cubic c ing volu ll fi s a g l l Natura lume 12 4.4 kg/100 km lling vo on Petrol fi sumpti s gas con l ra .84 euro 4 tu a N r 100 km 500 km e p t s o Fuel c ral gas ith natu Reach w 700 km ach m Total re 117 g/k ns/CO 2 io l Emiss 88 pacity 4 Boot ca A s s la c y c Efficien

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The Leon TG I expands SE AT’s mid-ra low-emissi nge car seg on natural ment by an gas-power equipped w efficient an ed model. ith a bivale d This sporty nt 1.4-litre for 100 kilo co m pact car is TSI engine tha metres. Th e Leon TGI t needs 3.5 its CO em is not only kilogram ission is lo 2 of a sporty w at 94 gra consuming smart desig ms per kilo natural ga n, metre. Init s model is more spaci ially, that lo available a ous ST esta w s a five-doo te car will fo r version; a llow. Output 81 kW/110 HP Maximum sp eed > 194 km/h Cubic capa city not spec ified Natural ga s filling volu me 15 kg Petrol fillin g volume 5 0l Natural ga s consump tion 3.5 kg Fuel cost p /100 km er 100 km 3 .85 euros Reach with natural ga s 420 km Total reach 1,360 km Emissions/ CO 9 Boot capaci 2 4 g/km ty not spec ified

English Issue

Biogas Journal | October_2015

Opel Zafira

Motion VW Golf TGI Blue Wolfstion of the VW Golf the With the seventh edi oped o offers a newly devel burg-based maker als TGI lf Go rged engine. The VW natural gas turbo-cha me kilo 0 10 only 3.5 kg for BlueMotion consumes the x, rbo gea G DS p seven-ste tres. Equipped with a 0 km. is as low as 3.4 kg/10 on pti sum con e averag ine eng s on with natural ga The Golf TGI BlueMoti ce sin n sio ver a hatchback has been available as 13. the late summer of 20 Output 81 kW/110 HP km/h Maximum speed 194 cm³ 95 1,3 ty aci Cubic cap ume 15 kg vol ing fill s ga al Natur l 50 Petrol filling volume 3.5 kg/100 km on pti sum Natural gas con 100 km 3.85 euros Fuel consumption per s 420 km Reach with natural ga Total reach 1,360 km m Emissions/CO2 94 g/k cified spe not ty aci Boot cap

One of the “classics” among natural gas-p owered vehicles is the Opel Zafira. The latest 1.6 CNG ecoFLEX turbo-charged version offers sport y driving dynamics with a 110 kW/150 HP engine at reduced CO2 emissions of 129 g/km. With an optimise d power train and a lightweight tank system holding 25 kilograms, the Opel Zafira Tourer runs 530 kilome tres in natural gas mode. The compact van with a len gth of about 4.60 metres The VW C comes with numerous addy is V safety features such as safety W’s long vehicles light system AFL+, tra runner a . T he new v ffic sign and lane assist mong th ersion is seater un ants, distance warni e natura markete der the c ng and l gas-po adaptive speed contro d as a fi o wered d e h ig T G l. A variable seat sys h I; ve-seate fl th e xi e b in ility. tem terior ap r or seve supports several differ pointmen nent seat arrangement t is desig s. ned for Output 8 1 kW Output 110 kW/150 HP Maximum /110 HP speed no Maximum speed 200 t specifie Cubic ca km/h d pacity no Cubic capacity 1,598 t specifie Natural g cm³ d a s fi ll ing volum Natural gas filling vol Petrol fill e 26 kg ume 25 kg ing volum Petrol filling volume 14 e 13 l N a tural gas l consump Natural gas consumpti Fuel cost tion 4.1 k on 4.7 kg/100 km per 100 k g/100 km Fuel cost per 100 km m 4.51 e Reach w 5.17 euros uros ith natura Reach with natural ga l gas 630 Total rea s 530 km km ch 830 k m Total reach 680 km Emission s/CO 11 2 g/km Emissions/CO 129 g/k 2 Boot cap m 2 acity not specified Boot capacity 1,860 l Efficienc y class A Efficiency class A

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Small mobile biogas plants for refugee camps Under the European project Speedkits, biogas microplants in refugee camps can improve hygiene and generate energy. These small power plants are developed in Germany. By Dipl.-Ing. · Dipl.-Journ. Martina Bräsel

The insulation of the digester is still a makeshift solution for the function test. A reel-up version will be used for the field test.

The challenges

P Hotos: Martina Bräsel

Gas storage bag: Weighted practically so the gas can escape continuously.

elpers were running into many problems after the earthquake in Haiti,” Michael Köttner says. For example, 520,000 people came down with cholera, almost 7,000 died. Possible causes were flooded cesspits in a refugee camp or the agent causing the disease was brought in by helpers. “The disease spread because the feces were simply dumped into the rivers,” the managing director of the IBBK adds. After this disaster, a European research project was started with the target of optimising the emergency units for use in crisis areas. “We proposed to add a small biogas plant and a hygieniser to the emergency unit,” Katrin Kayser explains. In this way, epidemics such as cholera or typhoid should be prevented, because the mobile small plant developed by the IBBK can kill the pathogenic germs found in human feces. The International Biogas and Bioenergy Competence Center (IBBK Fachgruppe Biogas GmbH, Kirchberg an der Jagst) is the only German partner in the consortium of twelve European member institutions. The Dutch Red Cross, other humanitarian organisations, companies and research organisations are also members. The project started in March 2012.

Each project partner assumed certain tasks under the project. For example, the IBBK not only develops the biogas microplant but also the hygieniser that kills the pathogenic germs and a mobile substrate receiving tank and a preliminary storage facility. These will take in human feces from the toilets in the camp in an easy to handle and clean process. “We work closely together with the manufacturer of the mobile toilets,” project manager Katrin Kayser says. This job was assumed by a Dutch company that developed simple raised latrines which work without any chemical additives. “The question of whether the urine should be separated was discussed extensively; finally we decided against it,” Köttner explains. Feces contain about 5 or 6 per cent dry matter, which is similar to pig manure. It is very important for the biogas process that the collected feces do not contain stones or garbage. “What kind of foreign material is present and whether it can be eliminated must be seen in the practical application of the process the way we conceived it,” the managing director says. “The development of a hygieniser to make the feces germfree was another challenge,” Köttner says. Most im-

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Biogas Journal | October_2015

At present, Katrin Kayser mixes the content in the vessel by kicking against the wall. This helps, but floating material is not dissolved sufficiently.

portant: The hygieniser had to be able to work alone and it had to fit the size of a standard pallet. The development of the actual biogas plant which had to be simple, small and mobile started only after the hygieniser challenge

had been solved. “Our job was to develop a light-weight, stable unit which was easy to set up and remove and simple to operate,” Kayser added. Therefore, the digester and the gas store had to be of a flexible shape. “The choice of the right materials was most important for us,” the environmental engineer explains, because they had to be tear-proof as well as resistant to ultraviolet radiation and heat. In addition, the small power plant was to operate reliably on the available substrates – human feces and ideally organic waste from fields and kitchens. Other important general conditions: The plant should not be dug in the ground and should sell at under USD 10,000.00. “Many different approaches to simple biogas plants are known,” Kayser says. Most operated on cattle dung and kitchen waste. “Thousands of household biogas plants which do not work properly can be found in for example in Nepal or India; these plants lack the absolute minimum level of equipment,” Köttner adds. These are sim-

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Biogas Journal | October_2015

Despite that, the biogas can substitute a not insignificant amount of fossil fuel. “How many people will actually use the biogas remains to be seen,” Kayser adds.

Pilot plant feeds on pig manure The primary purpose of the biogas plant is to kill pathogenic germs in human feces. This poses many questions to the experts because the optimum operating conditions (temperature, dwell time, substrate composition…) must be determined. For this purpose, they developed a small pilot plant. It is located on the biogas plant of the Blumenstock family a few kilometres away from the IBBK site.

Katrin Kayser demon strates how it works: The biogas can be carried in bags. People can use the gas for heating and cooking.

ply hydraulic systems fed manually. Then there are the biogas plants on farms and in the industry, for example in Germany, which are equipped on a fairly high technical level and run partly or fully automatically. “Our plant fits somewhere in-between.” The biogas concept of the IBBK avoided manual feeding and uses the simplest systems and equipment possible. “At first, a unit for 200 population equivalent will be built,” Eberhard Hager, who is responsible for design and technology, adds. Twelve cubic metres of digestion space are needed. “This size is based on the number of toilets,” he says. The toilets are set up in blocks of ten. About five cu• Exhaust Gas Heat Exchangers bic metres of biogas can be produced under these condi• Steam Generators tions, which people can use • Cooling And Drying Plants for heating and cooking. For Biogas “As it is, the biogas volume produced by a unit cannot supply more fuel than a basic volume,” the engineer guess/ es. That is because the energy content of the substrate is low.

The Chinese biogas cooker failed miserably already after the first doughnut. Another solution is needed.

The pilot plant has a total volume of three cubic metres, two cubic metres of which are for digestion. The plant feeds on pig manure. The pilot hygieniser has a volume of 300 litres. Its effect was tested by the Hohenheim University last year: “As was shown by the examinations, all important germs such as, for example, E. coli, enterococci, salmonellae and also cholera were killed reliably,” the project manager proudly explains. At present the processes in the unit are being optimised because many solutions must yet be found: For example, the supply of the electrical components (stirrers, recirculation pump and digester heater) is not clear yet. “We

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Biogas Journal | October_2015

have a manual pump which can be used very well for the transport of sludge,” Kayser says. However, that pump is not powerful enough to produce a sufficiently strong agitation in the digester. “We are still looking for an alternative,” the engineer says. The vessel of the unit consists of fabric and so Katrin Kayser still mixes the content by kicking against the wall of the vessel. This helps but fails to dissolve all floating material on top. “We will try and use a solar-powered agitator or mix hydraulically with a pump,” Michael Köttner says. Another problem is to provide sufficient heating for the digester. A workable solution is also needed for handling the digestion residue. When it cannot be used as fertiliser in fields near the camp, the only option is to collect it in a store and remove it by truck. “At any rate, the material we have at the end of the biogas process is less odorous and easier to handle,” Eberhard Hager adds.

GAS ENGINE TECHNOLOGY

Field test before this year is out The field test of the pilot plant will start before the end of the year. “Our next big task is to find a suitable site for the plant,” Kayser says. The site should have a fully developed infrastructure. This means the toilets must work and the waste and feces be collected. Only when this is clear will the biogas plant be set up. A new decision would then be taken after half a year or a year. “When the emergency camp becomes bigger and more permanent, we would consider building a larger plant,” Köttner is sure. If that happened, somebody would be needed to operate the plant. “I think anyone tinkering with a car will be able to do that job,” Kayser assumes. Whether this was really the case would have to be seen. It was also not sure yet if people would accept the gas and use it. People in the camp may collect gas and carry it home in bags on their backs and use the energy for heating and cooking. The first test under practical conditions was staged in the garden of the IBBK. Fortunately the biogas from the bag reliably supplied sufficient energy for the cooker. But the cheap Chinese biogas cooker already failed after the first doughnut. “We will certainly have to find a better cooker,” Katrin Kayser says laughing. She is already looking forward to a real practical test. A concrete site had not yet been chosen. Possible candidate countries are Madagascar, Malawi and Kenya.

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interview

»Turkey: interesting market with vulnerabilities« A talk with Alfons Himmelstoss, one of the first players in the biogas segment. As mechanical engineer, he was involved in the construction of a pilot plant as early as 1990; later he planned the biogas plant built by Josef Pellmeyer, long-standing president of the German Biogas Association and in 2005 he founded the AEV Energy GmbH in Dresden, a company planning and providing equipment for biogas plants. As managing director of the AEV, Himmelstoss has been undertaking commitments in Turkey since 2008 and is therefore one of the very few experts with a profound knowledge of the biogas scene in Turkey.

Interviewer: Dierk Jensen Biogas Journal: As a German biogas entrepreneur, what is your experience of the Turkish market? Alfons Himmelstoss: My experience is aligned on two sides. On the one hand, we have had a very positive experience with our customer in Samsun. Moreover, cooperation with our present Turkish partner is very systematic. On the other hand, the experience with our former partner in Antalya has been that obligatory payment deadlines were never met despite firm orders. An experience of the first few years was also that Turkish customers do not seem to have a problem placing orders without having secured the required finance. Unfortunately, it also happens that agreed payments and securities are simply ignored. We still have outstanding orders of almost five million euros from 2008. Biogas Journal: This sounds rather discouraging. What, in your opinion, is the biggest challenge in the Turkish market? Himmelstoss: The biggest challenge is to understand the difference between those customers who merely seek information and do not have the required financial basis and those who are ready to undertake investments in renewables with a clear understanding and are looking for a competent (German) partner. Another challenge is the cooperation with local partners and their quality and reliability. Any agreed construction and time schedule is more a rough orientation than a clear schedule to rely on. Another new experience was the time we spent on customs formalities, which was extreme at times. Plus there

were problems with installation deadlines. The assignment of the German chief installation technicians and the cooperation with local helpers who knew neither German nor English was extremely difficult and time-consuming. It is a big difference whether mechanics arrive at the construction site in Germany by bus or go on a mission outside Europe with only a few tools and limited time in which to complete a job. Biogas Journal: How much are foreign manufacturers and suppliers accepted in Turkey? Himmelstoss: The acceptance is mostly positive. To some extent, there is also admiration for the equipment from Germany. But when you get down to details in the negotiations you often hear: That may work very well in Germany but it’s all different in Turkey. Biogas Journal: Are there any Turkish manufacturers, project planners or suppliers of biogas components? Himmelstoss: As far as suppliers are concerned, we have been searching the Turkish market but could not find any that would have qualified. Their prices are incomprehensible to us; in some cases they were distinctly higher that what is common in Germany. So we buy our equipment and whatever we need for our Turkish projects exclusively in Germany. Some work of the project such as earth-moving work, foundations and vessels is usually contracted out to regional suppliers. Planning services are done by us and are generally not outsourced. No doubt, there may be suppliers of complete plants.

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Biogas Journal | October_2015

AEV activities in Turkey The first AEV project was implemented near Antalya. It was a 250-kW biogas plant digesting sewage sludge, manure, slurry, whey and kitchen waste. Last year, a plant near Samsun with 300 kW electric output followed; the digesters operate on different substrates such as screened domestic garbage, fish waste, sewage sludge, spoiled soybeans, slaughterhouse waste, blood and whey. At the same time, AEV prepared a feasibility study for the annual utilisation of 90,000 tons of household garbage in a local plant for the municipal administration of Sanliurfa. The study considers the sorting and separation of reusable material, the digestion of biogenic waste, the production of organic fertiliser, the use of the biogas for cogeneration or optionally as fuel for municipal motor vehicles. Even if the city commissioned the planning in 2014, the necessary funds have not been secured.

They offer simple systems with foreign (predominantly German) equipment. As soon as a project is more sophisticated, these suppliers will fall back to their foreign part-

ners. Whether their supplies and services are sustainable will be seen in the future. Biogas Journal: How do you judge the level of know-how of your Turkish partners in the biogas technology sector? Himmelstoss: The level of knowledge is very low. Without thinking about it, they explain that a biogas plant is something like a photovoltaic system or a wind power system; they simply overlook the enormous input for operation, maintenance and repair. The scope to which biogas technology has entered the Turkish market cannot be compared with Germany where anyone who is interested can go and see a biogas plant at work a stone’s throw away. And then there is the language barrier. Technical literature for private investors, whether printed or online, is available in German or English, little has been translated into Turkish.

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Biogas Journal | October_2015

The administrational reform of 2014 has not produced much improvement, though. Biogas Journal: What about compensation paid for electricity? Himmelstoss: The compensation amounts to 13.3 dollar-cents per kilowatt-hour electrical. This is enough for digesting organic residue. Biogas Journal: Are there any heat customers? Himmelstoss: Except for internal consumption, we have not been able to find customers who would use the heat. Heating grids are still non-existent.

Biogas Journal: Who are the investors in biogas technology in Turkey and what is their motivation? Himmelstoss: Most are waste disposal companies from the private sector. The interest by farmers is still surprisingly low. Some poultry and laying hen farms start showing interest in biogas. These farms consume enormous amounts of energy, and their waste from farming and slaughtering constitutes a serious environmental problem. In this segment, in particular, we are sure to have found a new concept for the mono-digestion of poultry manure. Together with the DBFZ gGmbH in Leipzig, we are running tests which are financially supported by the German Federal Economics Ministry in Berlin.

Biogas Journal: What are the biggest obstacles the biogas sector in Turkey is struggling with? Himmelstoss: The trend to gigantic construction projects is very distinct; this includes power plants. However, such projects often fail to materialise for lack of funds. Besides, corruption is another big problem. There are no independent courts, proceedings in courts of first instance take at least three to five years before a decision is made, and many decisions are appealed against because the losing party fails to understand the reasons for the decision. Moreover, contract compliance is an unknown concept and administration is a complex issue and very difficult to understand for us as foreigners.

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Biogas Journal: Is biogas in transport a topic? Himmelstoss: I believe there is still a very high potential in this field, indeed. Under the study in Sanliurfa, it is proposed that part of the biogas is used as fuel for municipal buses. This project is supported as a pilot project by the government in Ankara. Biogas Journal: In which segments do you see the biggest opportunities for expanding the biogas capacity in Turkey? Himmelstoss: Turkey is an agrarian country that should not be underrated; and it is growing. For example, Turkey is the world’s largest producer of citrus fruit. Still, biogas technology is just about making a start in that sector now. So there is immense potential in animal husbandry, slaughter houses, biogenic waste and the food industry. The degree to

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which the potential of about 5,000 megawatts electrical can really be used is not predictable. Development is lagging far behind what is possible. Biogas Journal: What do you think of the energy policy of the new Turkish government? Himmelstoss: First we will have to wait for the new government to be formed. Turkey still records a high economic growth but that is due in part to a high foreign trade deficit and growing national debt. The country has hardly any fossil energy sources worth a mention and therefore is forced to import enormous amounts. If the government wants to reduce that dependence, more energy must be produced domestically. At present, hydroelectric power plants are under construction on the rivers Euphrates and Tigris, wind power plants in the Marmara region, photovoltaic systems in the highlands and biogas plants throughout the country. But gas and coal fired-power plants as well as nuclear power plants are also in the pipeline. Which option the government will finally take is not for me to say. The trend to large projects is certainly not one based on renewability. Biogas Journal: What should be changed in the country’s energy policy laws to encourage farmers to invest more in biogas plants than they have been doing so far? Himmelstoss: There are several weak points to mention. Firstly, the application of liquid digestion residue as fertiliser on agricultural areas is not permitted by law. The prohibition

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also extends to untreated slurry. Secondly, the biogas compensation is limited to ten years, whereas 20 would be important. And thirdly, feeding is extremely difficult and costly in some cases. Despite these three points, the biggest obstacle is not the question of profitability but the lack of environmental awareness. Biogas Journal: Would the cultivation of energy crops be imaginable in Turkey? Himmelstoss: No, certainly not at this stage. In my opinion, the available potential of biogenic waste should be exhausted first. Besides, the production of energy crops is not an economic proposition considering the present feeding compensation. Moreover, it would not be possible to explain it to the people so they could accept it. Biogas Journal: Speaking about education and public relations work: Does Turkey has a biogas association that would be a stakeholder for the biogas sector? Himmelstoss: There is the Biogas Information Center (BIC) in Ankara. However, the association lacks much of the power of its German counterpart. Despite the high commitment of everyone working there, the association’s profile is still fairly low. Still, cooperation with the BIC is very important for us.

it starts paying off. For us, the Turkish market remains an interesting one. For example, we want to expand the biogas plant in Samsun, continue with the implementation of the Sanliurfa project and are designing the digestion of the organic fraction for municipal waste under yet another project. Besides, we have plans to cooperate with a Turkish university and the concept of digesting poultry manure is awaiting implementation. Despite all that: There are enormous risks; but these can be found in other countries as well. Eventually a positive development depends on only a few lines of text in a law. These lines are in effect in Turkey, at least for the time being, and grant biogas plant owners access to the electricity grid and a firm compensation for the product they feed. That’s all the safety we have. So we must remain flexible and look elsewhere as well, and that’s what we are doing.

Interviewer Dierk Jensen

Biogas Journal: What is the future of the AEV in Turkey? Himmelstoss: We have invested a lot of time in Turkey during the last few years. Gradually

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Farm biomethane plant

France

An ambitious change Large waste utilisation centres in densely populated areas converting waste or sewage gas – such as those in Lille, Morsbach and Strasbourg – are set up mainly in the municipal sector. Besides these, plants on farms are making up leeway such as that of Bioénergie de la Brie and pools of several micro-plants emerging under numerous local farmer initiatives.

Paris

By Marie-Luise Schaller

ith the Law on Energy Change and Green Growth, the French Ministry of Environmental Protection, Sustainable Development and Energy, referred to, in short, as MEDDE by the French, is bent on advancing the development of renewable energy sources not only with respect to the fact that Paris will be hosting the World Climate Conference in autumn. The targets are to increase the share of energy from renewable sources to 23 per cent of the energy demand by 2020 and to 32 per cent by 2030. These sources should provide 40 per cent of the electricity generation and 38 per cent of the heat end energy, 15 per cent of the motor fuels and 10 per cent of the gas end energy. The fundamental change in French energy policy is not yet consolidated legally because there will be a second reading of the Bill which will not be adopted earlier than at the end of May/beginning of June. Parallel with the legislation process, however, working groups and commissions are working out the implementation regulations and provisions, and different actors in the energy market are making their contributions to the development of the growing market. Experts of the French government and the energy sector believe that biomethane will have a great future, as was stated during the biomethane conference organised by

the German-French Bureau of Renewable Energy on 26 February. Some details from the papers delivered at the conference and the latest publications will be discussed below.

From 6 plants now to 44 by the end of next year At present, six plants produce biomethane. They feed over 70 million kilowatt-hours into the French natural gas grid every year. The use of energy crops only is a great taboo in France. Two legacy plants, a biogenic waste and composting plant in Lille and a biogenic waste plant in Morsbach, digest biogenic substrate. The other four plants operate on farming substrates and residues. Maize can be grown as an intercrop here. Another 38 plants are hoped to start production this and next year, so that the total number may go up to 44 by the end of 2016, as was reported by the GrDF in the paper by Suzanne Renard. The plant in Lille-Séquedin was the first to feed biomethane into the French natural gas distribution system. It is owned by the companies of the Communauté Urbaine Lille Métropole. The biogas, which is produced from preselected biogenic waste, is treated by pressure scrubbing. The annual output of 16 million kilowatt-hours fuels 150 municipal buses and 80 trucks. Between 15 and 50 per cent biomethane is added to the natural gas.

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Biogas Journal | October_2015

Another 320 buses can also run on biomethane. As Dr. Marc Jean Mestrel as involved adviser reported in his paper, many directives and technical solutions were developed in this pilot plant in a long series of tests and examinations until the gas-fueled vehicles were financially as profitable as diesel engine-powered trucks. Feeding the biomethane into the natural gas network and fueling the vehicles during the night have a positive effect on the cost return situation. The Méthavalor plant in Morsbach (see photo on this page) also digests biogenic waste. The waste is collected from local communities with 385,000 inhabitants altogether. The biogas is treated in a membrane unit from AirLiquide. A total of 9 million kilowatt-hours are fed into the natural gas grid every year. The farm plant of Bioénergie de la Brie in Chaumes-en-Brie consumes 12,500 tons of farm residue, among that slurry from 500 head of Limousine cattle and from 250 suckler cows with calves. If there were no seasonal limitations for the feeding of biomethane in the natural gas grid for capacity reasons, a total of 16,000 tons of input materials could be digested. The biomethane from this plant is also treated in a membrane system from Air Liquide; it produces 125 standard cubic metres of biomethane an hour. The other farmbased plants have the same output capacity. A PSA plant is located in Mortagne-sur-Sèvres; membrane systems are installed in the plants in Sourdun and Ussy-surMarne. One of the interesting projects not yet completed is the Biovalsan plant in Strasbourg, where biomethane with an energy potential of 16 million kilowatt-hours a year will be produced from the gases of France’s fourthlargest sewage treatment plant.

Abbildung 1: Aktueller Bestand und derzeitige E Biomethananlagen in Frankreich (nach Angaben Figure 1: Present stock and expected development of biomethane plants in France (data by GRdF)

Existing plants: Biological waste Agriculture

Number of biomethane plants which should go on stream by the end of 2016

Abbildung 2: Biomethan-Einspeisetarife 2015

The environment and energy targets are related closely to the growth of the economy and the consolidation of the home budgets. Heating cost will drop, means of transport become cleaner and jobs be created. Biomethane is an important player in these plans as part of the natural gas supply and also as a fuel. The production targets will be fixed by mid- or end-August, after the promulgation of the Energy Transition Act. Questions of policies and regulations are discussed intensively between Germany and France. Under the European Green Gas Grids project, the ADEME Energy Agency developed two potential scenarios for France, engineer Olivier Théobald explains. According to these, the available materials – no change in the development trend given – are sufficient for supplying 500 plants with 12 billion kilowatt-hours, and – when the development is forced – for 1,400 plants with 30 billion kilowatt-hours. At present, over 600 biomethane projects are in the pipeline in France, of which - according to GrdF - 400 plants will feed biomethane into the general distribution system and 200 into the transport grid.

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Strategy and potentials

Méthavalor in Morsbach (F) – biomethane production from biogenic waste.

Clean air with biomethane Yet another restriction was imposed on motorcar drivers in the conurbation of Paris on Monday, March 23rd: To reduce the fine dust pollution, only vehicles with uneven registration numbers, electrically powered and hybrid vehicles as well as carpools of more than three persons are permitted to use their vehicles; public transport is free. At the same time, the Paris Municipal Transport Services, RATP, and the gas supply company GDF SUEZ made it known that they had agreed to a three-year partnership. Together they will advance the gas-fueling for bus depots so that the RATP vehicles run on natural gas and

Quelle: Vortrag Stanislas Reizine, MEDDE

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Biogas Journal | October_2015

Biogas production from sheep manure – a Franco-German success story

P Hoto: novis GmbH

biomethane. The target is to use only environmentally compatible vehicles within a period of ten years: 80 The product of successful cooperation is per cent electrical and 20 per cent on biogas. evaporator and returned and mixed with the being broken in in Rullac-Saint-Cirq: the This decision enables the GDF Suez, via its subsidisolid manure by a specially developed mixsheep manure plant of the French Arkolia ary GNVert, to participate in the development of natuing screw. This produces valuable fertiliser Energies and the German novis GmbH from ral gas-powered vehicles, a market considered to be which contains nutrients of short-term and Tübingen. At present, the plant still feeds on promising because CO2 is saved and particulate emislong-term availability and is particularly Abbildung 1: Aktueller Bestand und derzeitige Entwicklung von sions are reduced. At the same time, this development 100 per cent sheep manure. Farm waste (for suitable for organic farming. Regrettably, Frankreich (nach vontoGRdF) makes betterAngaben use of waste materials produce bioexample, rapeseed dust) is a Biomethananlagen potential addiplant owners in France in cannot make commethane-CNG. As many as 90 natural gas-powered tion in future. The principal units, in which mercial use of the digested fertiliser except buses are already stationed at the Créteil base; the ca6,000 tons of substrate are digested every in their own fields. pacity will be expanded to 220 vehicles by mid-2015. year, are the hydrolysis container, a digester The advantages of the partnership are obvi(1,000 m³), a post-digester and a 250-kWel ous: Whereas Arkolia takes care of the loConditions and prices cogeneration unit. cal customers, the approval procedure and Every biomethane producer can enter into a 15-year Sheep manure has a high content of straw, the financial aspects of the project, novis contract with any gas supplier. The gas supplier pays which is a particular challenge: At the first invests the experience of the German biothe statutory feeding tariff for biomethane and restage, hydrolysis, the substrate soaks for 24 gas sector into the success of the project. ceives the difference to the price of natural gas from a hours, is converted into a pasty mass and Construction management and start-up are compensation fund. The MEDDE defines the relevant preheated to between 39 and 40 °C. The shared activities. The distance to Tübingen reference price of biomethane. The amounts paid hydraulic dwell time of the substrate in the is no problem as all units of the plant have from the compensation fund are charged to all gas usplant is about 95 days. All the biogas is conremote control facilities. At the end of the ers. Biomethane is supplied with certificates of origin verted to electricity. A separator separates start-up phase, Arkolia will be responsible in France. the substrate from the post-digester. The for the maintenance and the biological Plants with a small treatment capacity receive higher liquid phase is concentrated in a vacuum management of the plant. support. For example, plants on farms and forestry plants with up to 50 standard cubic metres per hour (Nm³/h) can claim compensation of 130 euros for each megawatt-hour (MWh), which drops to about 87 euros per MWh for plants with 350 Nm³/h capacity (see Figure 2). The fairly high feeding rates are the result of the fact that 100 per cent of the cost of the feeding plant must be borne by the plant owner. In France, different types of waste can be processed. Special tariffs are in place for biogas plants which use the biogas for biomethane production and also for electricity generation. Biogas plant RullacAbbildung 2: Biomethan-Einspeisetarife 2015 Figure 2: Biomethane feed-in tariffs in 2015 Landfill gas

Municipal waste

Agricultural and forestry residues as well as waste from the food industry

Sewage treatment plants

Feed-in tariff 2015 (e/MWh)

Saint-Cirq/F (Département Aveyron).

Feed-in capacity (Nm3/h) Source: paper by Stanislas Reizine, MEDDE

Quelle: Vortrag Stanislas Reizine, MEDDE

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Hurdles and challenges The approval process for biogas production is made simpler by bundling the relevant procedures. The national approval of digestion residue as fertiliser is a desirable target, as is the speedy approval by the ministry of the expansion targets to be implemented in the regions. The implementation of the large number of biomethane projects is supported by measures taken by the gas grid provider GRdF: Public relations activities to raise the awareness among the population, selection of feeding points near available grids with sufficient capacity to accept the volume of biomethane fed, and provision of advisory services to project developers. The ministry analyses the initial cost reports for the plants, and it can be expected that the feeding tariffs will also be reviewed. Most projects will probably be realised in the farming sector. Many small feeding plants may not be able to operate on a profit. So there are initiatives to bring several biogas producers together in one feeding plant. Such a project is currently in the pipeline in Brittany by the farming cooperative Triskalia in cooperation with semaeb, a regional project developer, and direct energie, a local enery supply company. The question of how the available subsidies should be adapted to the new structure must still be worked out, Mr Chapelat of semaeb explains. The production of biomethane as fuel also requires changes to the current general framework such as the development in the vehicles segment or the net of natural gas filling stations. This has been set out in a white book published by ATEE Club Biogaz, the largest biogas association in France.

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Promising prospects for sustainability The French energy and environment policy relies on energy from renewable sources, closed-loop economy and clean transport. Biomethane offers ideal preconditions for the implementation of this policy by the municipal wastewater treatment and waste-processing firms and by transport companies. Looking at the invitation to tender for 1,500 biogas plants within the next three years, the potentials available in farming can also bring their weight to bear. It remains to be seen what general conditions for the biomethane sector the ministry will announce after the summer break. Promising concepts have been developed in the meantime. The next biogas exhibition in Paris, ExpoBiogaz, will certainly highlight more interesting developments. And the events organised by the German-French Office for Renewables will certainly also take a look across the border and focus on direct comparisons with the conditions in Germany.

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from the first over the large BiogasView Journal | vessel October_2015 construction site at Vojens.

Denmark

BOOM-BOOM-SLURRY

Kopenhagen

The digestion of slurry is very popular in Denmark. The general conditions under energy legislation are favourable so that the sector expects the generation capacity to double by 2020. By Dierk Jensen

Farmatic man from the start: Chris Lilienthal setting up a vessel.

strong westerly wind dishevels the hair of managing director Claus Mikkelsen on the 25-metre high roof of the digester. The awns of barley and triticale grown in the nearby fields are dancing their Jutland summer dance in a cheerful mood. And not far away from the biogas plant the medieval brick tower of the church stands out from the plain of the Southern Danish town of Ribe. “The biogas sector is being turned upside down in Denmark at present,” Mikkelsen, of Ribe BioGas A/S, one of the largest biogas plants in the world, which will be 25 years old in June, says. “We are seeing a system change. The supply market we were used to is turning into a demand market,” he explains. “The four big actors in the Danish gas market, among them NGF Nature Energy and E.on Denmark, are entering the biogas market and will be feeding biogas into the gas distribution system on a large scale,” he explains. “They are planning methane feeding projects the size of over 10 megawatts each site. This is the reason why the prices for waste materials are going up dramatically.”

The government encourages the digestion of slurry There is a good reason for the sudden commitment by the large investors: The production of biogas from slurry is expressly encouraged by the Danish government, will be ex-

panded further and is promising high returns. In addition to a fixed compensation of 1.15 Danish crowns for every one kilowatt-hour, Danish investors can hope that 30 per cent of the entire amount they invest in the construction of a new biogas plant will be subsidised by the government – if money is available, which is not the case at present. Not counting that, biogas is an important element of the ambitious Danish climate and energy policy, the target of which is that Denmark should be a carbon dioxide-free society by 2050. As part of this process, biogas plans are that half the total amount of slurry should be digested by 2020. The fact that Danish farmers consistently rely on farm waste is shown by the way they grow energy plants. Even if biogas plant owners are free to use maize at any rate they want, the biogas compensation of 1.15 Danish crowns per kilowatt-hour adopted by the Danish parliament in 2012 is only paid if the substrate consists to not more than 25 per cent of energy plants. This limit will be reduced by another 12 per cent in 2018. But that worries hardly any Danish biogas producer because very few of them use energy plants. “I guess that only one or two per cent of the substrate digested in the country’s biogas plants is from energy plants. Even if energy maize is cultivated on up to 20,000 hectares of land, most of that is exported to Germany,” Bruno Sander Nielsen, managing director of the Danish Biogas Association Brancheforeningen for Biogas states. “We will not expand that acreage. We would like to stick to the Danish biogas model of slurry and waste.”

Large CO2 footprint in Danish farming

As a result of these projects, a run on slurry as a coveted biomass has set in – at present unimaginable in Germany.

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photos: by Dierk Jensen

Biogas Journal | October_2015

Claus Mikkelsen in the factory hall of Ribe BioGas A/S, in which energy plant silage is stored and waste is fed to the digester.

The slurry tanker is pumping slurry into the tanks of Ribe BioGas A/S.

This is nothing new for the actors of the Ribe BioGas A/S. “You should remember that the CO2 footprint of Danish farming is structurally high. We have a high density of livestock and produce a lot of meat, much of which goes into export. So the digestion of slaughterhouse waste and the conversion of farm waste into energy had already been in focus for the founders of this company in 1990.” At that time, the founders, among them 50 farmers as limited partners and the town of Ribe, contributed about a million euros. Total investments since then have gone up to about 5.5 million euros. At present, the plant can produce a total of 2.6 megawatts, for which two Jenbacher units as satellite cogeneration units produce heat on the outskirts of the historic old town. The heat is fed into the local heat supply system. Another cogeneration unit with 500 kW output was installed on the premises of the biogas plant in 2014. That unit is the result of the increasing production of gas made possible by the recent completion of the change of the plant design. The dwell time of the slurry was doubled from 11 to 22 days. “My job is to get as much gas as possible from the slurry,” Mikkelsen, who has worked in the Middle East for many years, underlines the ambitious process of thermophilic digestion. This will be entirely what the farmers expect, from whose farms within a radius of 10 kilometres of the biogas plant 750 tons of manure are collected every day. Three trucks collect the slurry. In addition to slurry from 47 dairy farms with an average of 200 head of cattle and three big pigrearing farms in a radius of 5 to 10 kilometres, slaughterhouse waste, which accounts for about 15 per cent of the total quantity collected, organic waste from food retailers and some energy plants are taken in.

Large job for Farmatic An even larger biogas plant is under construction South of Vojens. In the direct vicinity of the local military airport a biomethane feeding plant with an annual production

A truck is seen dumping substrate from the food processing industry.

volume of 21 million cubic metres of biomethane is being built on a 20-hectare plot. The total investment amounts to an impressing 33.5 million euros. Whereas the Swed ish company Purac Puregas AB is the contractor for the methanisation plant, the Farmatic Anlagenbau GmbH from Nortorf won the contract for the planning and construction of the biogas plant worth 16 million euros. Work started at high pressure in May. Several wheel loaders move immense quantities of earth, at the same time Farmatic teams are erecting the first vessels of a total of seven main digesters. Meanwhile, Hans Hendrik Hansen, Farmatic International Sales Manager, and project manager Rüdiger Johannsen explain the project in an office container. “The plant we are constructing here is owned to 50 per cent by E.on Denmark and 50 per cent by Sonderjysk Biogas Invest (SBI) A/S, which in turn is wholly owned by a supply cooperative society of 60 farmers. The plant owners invest about 12 million euros in the construction of the plant. The investors expect a return of 10 per cent on their investment,” Hansen says. “The farmers will supply a total of 540,000 tons of substrate. Most of that is slurry collected from farms in a radius of 15 to 20 kilometres. Plus 50,000 tons of sugar beet, 50,000 tons of straw and 15,000 tons of maize silage,” the Farmatic man adds. Production will start in August 2016. The treated biogas will then be fed at 80 bars pressure into a nearby gas pipeline of the supplier Energinet dk. Hansen, an old hand in the biogas sector, guesses that the large Vojens project will not remain an isolated case. “My conservative estimate is that maybe about ten other methanisation plants of similar size will be added in Denmark,” he says looking ahead. “The plants must be big,” he says and explains that the cost of smaller biogas plants feeding on 75,000 tons of slurry a year work out at about 80 euros a ton whereas for a plant the size of Vojens it is only 65 euros, Hans Hendrik Hansen is sure. Farmatic will participate in this potential development; proposals

English Issue

Biogas Journal | October_2015

“Generally, I believe that double the present number of plants may be built in the next few years” Hans Hendrik Hansen

Hans Hendrik Hansen and Rüdiger Johannsen of the Farmatic Anlagenbau GmbH on the large construction site near Vojens.

Anders Rosenkvist explains the operation of his plant in Skaerbaek: “The design is as simple as possible.”

for two more large projects had been submitted. “The bigger the better” is also what Bruno Sander Nielsen of the Danish Biogas Association believes. He is very satisfied with the present development. Whereas the proportion of digested slurry was about seven per cent in 2014, it will go up to 15 per cent by the beginning of next year. Still: Looking at 35 million tons of slurry a year in Denmark, much remained to be done. So the managing director of the small Association with 65 members expressly welcomes the commitment of the Danish energy suppliers in this sector. Biogas is a major element in the portfolio, Susanne Tolstrup, communications manager of E.on Denmark, underlines: “Because the gas network in this country is very dense, there are good options for feeding the gas into the network everywhere.” The fact that the production of biogas offered a financially sound long-term future was certainly a fillip to the readiness of E.on and the other big actors in the energy industry to invest in this sector. In Danish legislation, the compensation paid for biogas is tied closely to the market prices for natural gas. When the price of natural gas drops, the compensation goes up automatically, and vice versa. Besides, the demand in the transport sector is also rising because the Danes have to make up leeway before the European target of supplying 10 per cent of the fuel needs of a country from renewable sources

can be reached. For example, E.on Denmark also intends to invest in a system of filling stations for heavy trucks. So, sunny prospects everywhere in Denmark? Not quite, because Danish farmers – like farmers in other European countries – are hit hard by the low prices they are paid for milk and meat. Moreover, many banks have completely withdrawn from the farming business. “We, the Association, do hope that this crisis in farming will be overcome soon,” Association president Nielsen notes, “because the biogas business will not be able to develop organically unless agriculture works.” How difficult the situation in dairy farming really is, can be seen at the farm of Anders Rosenkvist in Skaerbaek. Not a trained farmer and born in Copenhagen, he purchased the farm and increased the livestock to 200 head of cattle. “I will stop milking before this summer is out,” the 52-year-old farmer says, smoking his pipe. “It does not make sense for me any more.” In future, he will only operate the biogas plant on the farm, which produces 1.8 million cubic metres of biogas a year. Some of the gas is converted to electricity on site; most of it is supplied to the municipal cogeneration unit through a pipeline he built. The heat from cogeneration provides sufficient heat to about 350 buildings. Even if the energetic self-made man does not say anything about gas prices and production cost of his biogas plant – “as simple as possible” – it is very clear: Biogas is a better earner than milk in any case. One other thing is also clear: The competition for the substrates and for the most favourable heat prices in the rural and urban areas will become more fierce in future. “The situation will not become easier for actors like Rosenkvist,”

Anders Rosenkvist has 200 head of cattle of the Danish Hereford breed in the shed in Skaerbaek.

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Biogas Journal | October_2015

A view of the plant of Ribe BioGas A/S from the roof of the main digester.

How to Make a Lot of Money from Biogas Residues!

“We, the Association, do hope that this crisis in farming will be overcome soon” Bruno Sander Nielsen consultant Karl Jørgen Nielsen cautions. He used to work for the Farmers’ Association and is now employed by the engineering and planning office PlanEnergi in Åarhus. He knows all the problems in farming and at present is responsible for the efficiency improvement project which is financed by the Biogas Working Group under the umbrella of the Danish Energy Agency and the Danish Biogas Association in which 15 biogas plants take part. Besides, he also studies the possibilities of digesting straw, and biogenic waste, which is also becoming ever more important in Denmark, is another focal area for him. Despite that, Nielsen is hopeful that farmers will not be reduced to mere providers of substrate and will survive as investors in the biogas sector. Because, in addition to the large projects, smaller, site-adapted, really local plants remain a viable option for sustainable farming. So that the awns of barley and triticale can be dancing their summer dance also in future.

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Biogas Journal | October_2015

Vo Chau Ngan is demonstrating the gas development of different substrates to students of Can Tho University.

Vietnam

Hanoi

Potential: 10 billion cubic metres of biomethane In Vietnam, biogas is mainly a success story of small home plants. Now compensation for feeding electricity from biogas plants may advance the technology to a larger scale. By Klaus Sieg

o Minh Luan takes a run-up and jumps onto the digester. Even if the black plastic film buckles under his wide strides, it is sufficiently filled with methane to support the weight of the 51-year-old man. Like a bouncy castle at a party for children. Do Minh Luan slides down again, a satisfied smile in his face. “The plastic material is tough enough to take that.” Quite an accomplishment, because it spans a 1,800 square metre large vessel, six metres deep, in which up to 8,000 cubic metres of pig manure are being digested. When the digester is full, it contains up to 4,000 cubic metres of methane. The farmer is not only satisfied with the construction of his biomethane plant: “After only two years, we have recovered two thirds of our investment.” Do Minh Luan is the manager of the Greeco Farm. The pig fattening farm in the village An Trach Dong in the province Provinz Bac Lieu in South Vietnam is a family business. It is managed by his brother Do Minh Nha. The family started with a small shrimp farm only a few years previously. They changed to pig fattening three years ago. Today they fatten 4,500 pigs. Most of them are sold to a trader who takes them to Ho Chi Minh City. With over seven million inhabitants, Vietnam’s largest city with a growing middle class is a good market. So the Greeco Farm earned a profit quickly.

Iron chips against hydrogen sulfide So, much of the roughly 40,000 euros for the digester was paid for by the family. For that price, the Vietnamese plant supplier Apo Corp. from Hoh Chi Minh City supplied them with simple but reliable equipment. For example, water is

filtered from the methane in discarded blue plastic barrels from BASF. The biogas flows through the barrels. The high temperature causes the water to condense on the walls of the barrels and can be drained. The dry methane then enters the power house. In a prior process, iron chips remove the hydrogen sulfide from the biogas. The hydrogen sulfide causes the iron to turn to rust. “We must replace the iron chips every two months, but we get the chips free.” The clatter in the cogeneration house comes from generators of the Japanese supplier Tayio and the US company Magna Max. Second hand, these machines cost a little less than 30,000 euros. “They have been giving reliable service so far; they had clocked up only 1,500 hours when we bought them,” Do Minh Luan shouts against the noise and wipes the perspiration from his forehead. With an output of about 600 kilowatts electricity, the generators provide a fast ROI. They run about ten hours a day. The electricity is supplied to the pig farm, most of it to a neighbouring shrimp farm 20 hectares large.

13 eurocents for peak load current It needs the electricity to drive the propellers pumping oxygen into the densely populated basin. The shrimp farm pays almost 3,000 euros to the Greeco Farm every month. In return for that, the farm supplies electricity reliably, mainly in times of peak demand, in which one kilowatt-hour costs 13 eurocents. “Blackouts of the type we know from the public grid do not happen here,” Do Minh Luan says. The environment also profits from this. Formerly, the Greeco Farm simply dumped the manure

English Issue

PHotos: Martin Egbert

Biogas Journal | October_2015

Researcher Vo Chau Ngan of Can Tho university in front of the model of a small home-based biogas plant.

into a pit and sterilised it with potassium carbonate. Today, the solid residue from digestion can be sold as fertiliser. So everything is okay with biogas in Vietnam? An agrarian country, Vietnam has a high potential of animal waste and residue from sugarcane, rice and starch production. Add to that the organic waste of the growing landfills in the cities, as well as contaminated water from sewage treatment plants. Ten billion cubic metres of methane per year could be produced by all sources together. And the country is in need of new energy sources, no doubt. Vietnam has seen a sizable economic growth for a number of years; it amounted to a little less than six per cent even directly

after the global economic crisis of 2008. However, the infrastructure, like the energy supply, cannot keep up with that development. Energy consumption will rise to 330 billion kilowatt-hours a year by 2020, meaning it will have trebled within ten years. Opposed to that is an installed capacity of 21,542 megawatts.

The manure from four heads of Zebu cattle and twenty pigs is enough to operate the 10 cubic metre biogas plant of Le Thi Thanh Thuy.

1,700 MW a year would have to be added Hydropower contributes 40 per cent to the total electricity generation. Shortages and blackouts are frequent outside the rainy season. Coal is becoming a scarce resource which Vietnam will soon have to import to fuel the power

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Biogas Journal | October_2015

Le Thi Thanh Tuy is seen filling water in the shaft of the digestion vessel to detect leaks.

Compensation only for landfill gas so far

Five cubic metres of manure are in the process of digestion under the plastic film in the small garden of Ha Nguyen Vu.

The demand for electricity is growing due to the rapid economic growth.

plants in the country. To satisfy the rising demand for electricity, 1,700 megawatts would have to be added every year to meet the demand forecast in the master plan of the Vietnamese government in 2011. Renewables figure high in the plan. Their share in the generation of energy is to go up to 5.6 per cent by 2020, which is almost double the amount of 2010. Biogas and biomass should contribute 500 megawatts, according to government plans. Despite that, experts estimate that the number of large biogas plants in the country is less than 20 at present. Not all of them generate electricity, not even the government’s showcase Go Cat power plant with three generators, each of which supplies 2.4 megawatts. They are out of operation for most of the time. Besides, the associated landfill in Ho Chi Minh City is facing closure. Many operators simply burn the methane because it is produced when they dispose of the waste as prescribed. Some obtain process heat from it such as in processing cassava or in piglet rearing. Some plants have even closed down completely, for example, the one in a fish-processing factory near the city of Long Xuyen in An Giang Province. Actually, short of 40,000 cubic metres of wastewater should be digested under the black plastic film. The faded cover hangs loosely over the pit and the power house is empty. Only a small building site generator is covered with dust. The owner says he wants to buy a 300-kilowatt generator but lacks the required funds. The bank is not willing to hand out a loan for a biogas plant.

Despite the unquestionable potential, the country lacked a feeding regulation with a compensation that permitted a biogas plant to operate at a profit. This has changed recently. Since mid-2014 compensation is paid at least for electricity from landfill gas. Even if 7.28 dollar-cents per kilowatt-hour is not actually what producers in the region might have wished for (it is not more than the tariffs for electricity from wind or solid biomass), it marks a beginning. A feeding tariff for electricity from biogas plants using farm or food substrates is to follow soon. “These first steps are correct and important. We strongly assume that the market will now develop continuously,” Tobias Cossen of the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), which played a role in drafting the regulations, says. “Examples from other countries in which excess subsidies at first unleashed a boom, which was followed by a total collapse of the market, abound,” Cossen adds. All aspects of feeding, both in technical and commercial respects, are handled through the government supply company VietNam Electricity (EVN). The direction in which the biogas sector will develop after a feeding tariff is in place also depends very much on that monopoly holder. All that should not worry Ha Nguyen Vu – at least as long as the two sausage-shaped bags of transparent plastic film under the wooden shack on piles are tightly filled. The methane in the bags is obtained from a pit in the pig sty, which is also covered with gas-filled plastic film. Five cubic metres of dung are digested in the small garden in the village Khanh An in An Giang Province in the delta of the Mekong River, all from the ten pigs dozing away in the shady sty. A gas pipeline runs from the pit through forage grass and sugar cane stalks to the two vessels at the house. “You need them to build up sufficient pressure,” the farmer, who is also a portrait photographer and repairs clocks, watches and sunglasses for his neighbours, explains.

Mice eat up the plastic film cover A tinkerer, he built the biogas plant himself. The material did not cost more than the equivalent of forty euros. Two water-filled plastic bottles serve as pressure gauge for the two hoses under the house. When the pressure is high, bubbles rise in the water. In that case, Ha Nguyen Vu must either burn the gas in the cooker on the wooden floor amidst pots, pans and woks in his small kitchen or reduce the pressure by other means. The plastic film on the pit is his only source of trouble. “I must replace it every year because either the mice eat it up or a chicken picks a hole in it,” Ha Nguyen Vu smiles and takes a drag on his cigarette. This is why the An Giang Bioenergy and Sustainability As-

English Issue

Biogas Journal | October_2015

sociation (ABSA) does not build that type of home plant. “We favour spherical digesters made of bricks set up in the ground near the stable,” Pham Thi Hoa, president of the Association, says. She receives us in the conference room of the Ministry of Agriculture of the province in Long Xuyen, where she and the secretary general of ABSA, Nguyen Minh Trang, have their desks. Busts of Karl Marx and Lenin in a glass cabinet and photos of Ho Chi Minh and several football cups adorn the room. The home plants are built under a government scheme which is mainly financed by the Dutch development aid organisation SNV. Small farmers can obtain grants and low-interest micro-loans for home plants between six and about ten cubic metres. “Even very small farmers with two cows or six pigs have sufficient amounts of dung to run a biogas plant that provides the energy they need,” Pham Thi Hoa explains.

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Micro-plants save 6.34 tons of CO2 every year

Under the program,145,000 have been installed in over forty provinces so far. One plant saves 6.34 tons CO2 per year, on average. Less wood is burnt and the contamination of the environment by untreated dung and the use of mineral fertiliser is reduced. The residue from digestion is spread in the fields and gardens. ABSA alone installed 1,350 such small plants in the province. This is done for the organisation by a team of 35 contractors. One of these plants is located directly opposite the wood shack of tinkerer Ha Nguyen Vu. A small bridge crosses one of the innumerable channels in the Mekong delta and leads to the farm of Le Thi Thanh Thuy. Together with her husband, she has been producing biogas in the plant that holds close to ten cubic metres of manure and which a pipe connects directly to the stable with four heads of Zebu cattle and twenty pigs. “The size of the plant is calculated on the number of animals,” Nguyen Minh Trang, of ABSA, says. “Each animal should produce 75 kilograms of dung a day.” Farmer Le Thi Thanh Thuy is sitting on a plastic chair in the small kitchen. Hanging from the wall is a transparent hose with water, in which she can read the pressure in the system. Le Thi Thanh Thuy’s husband is on the way. He sells ice blocks to shops, homes and restaurants in the area, which he buys in a factory. “This is a main source of income for us, in addition to animal husbandry,” Le Thi Thanh Thuy explains. She cooks three meals every day, for herself, her husband and three children. She often also cooks for her sister’s children. She does not need to buy gas any more. “The gas from the biogas plant has always been enough.” This saves the family the equivalent of 150 euros a year. She pays back forty euros a year for the loan which she needed for the biogas plant that cost 400 euros.

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University studies the technical development Biogas at a small scale is very successful in Vietnam. This is due to a not insignificant degree to Nguyen Vo Chau Ngan from the university of Can Tho, the largest city in the Mekong delta. Even if the plastic hose of the pilot plant in which the gas is stored was not filled with gas when we saw him. Happily, there are students. They compress the methane in the hose. In this way, Nguyen Vo Chau Ngan can demonstrate how well biogas burns in the small cooker. The researcher and his team do much more, however. Biogas has been a topic in Vietnam from as early as the 1960s.

WWW.HAFFMANS.NL 41

English Issue

Biogas Journal | October_2015

The second-hand generators in the power house of the Greeco farm give good service; they produce about 600 kilowatts electricity.

Ha Nguyen Yu in front of his fireplace that uses biogas he produces.

The research work stopped when the United States entered the war at a large scale from 1965 but was resumed quickly after the end of the war in 1975. The researchers at the university of Can Tho developed very many different designs of home plants, tested them at the laboratory and in the field. Moreover, they are also looking for suitable substrates. Except animal manure, the delta region with intensive agricultural use offers many other substrates, mainly rice straw and water hyacinths, which grow wherever there is water. They are removed every year to keep the waterways and fishponds clear. “Even if pigs or cows are reared in very many households, mostly their number is small and they are sold for the New Year festival,” Nguyen Vo Chau Ngan explains. “At that time there will not be enough dung to feed the biogas plant.” So models that also work with other substrates are needed.

Benefits must be communicated wider Water hyacinths require more frequent and more intensive stirring in the biogas plant than dung. And they need a larger digester. “In return, plants with mixed substrate produce more biogas.” If pig manure is mixed with rice straw or water hyacinths, the plant produces almost double the volume of methane. Besides, the quality of the residue as fertiliser or for feeding the fish or shrimps is better. “We must make people understand that the biogas plant can do more than just save them the money for the fuel.” Moreover, suitable small generators could produce electricity in the larger small plants. Despite the fact that at present many actors are waiting to see whether and how the production of electricity in larger biogas plants will develop, there is still a lot to do also in the field of small home plants. The Greeco Farm will soon expand the generation of electricity from biogas. “We are building another two sties for a total of 3,000 pigs.” Manager Do Minh Luan points to the new building where bags of cement plaster are being unloaded. When ready, the methane from the pig manure will suffice to feed three gas generators almost around the clock. They can produce electricity for 18 hours a day already now. But what to do with the electricity? Feeding into the public grid is still in its nascency and the required machinery and equipment is very expensive. The Do Minh family has other plans. They will power ice-makers with methane without converting the gas to electricity first. This should be their next success story. Because the favourite drink in Vietnam is beer on ice. Reminds me somehow of the bouncy castle.

Author Klaus Sieg Freelance journalist Rothestr. 66 · 22765 Hamburg

Two house tanks (underneath the porch) of Ha Nguyen Vu‘s self-constructed biogas plant; two filled plastic bottles serve as pressure gauges.

Phone +49 (0)40 380 89 359 16 e-mail: klaus@siegtext.de www.siegtext.de

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Biogas technology, flexible and tailored to fit

Biogas Journal | October_2015

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