Standalone Solar energy system for a distillery by Abdul Studio

Standalone Solar Energy System for a Peruvian Single Malt Whisky Distillery

ABSTRACT

For this project work, a stand-alone, hybrid energy system composed of photovoltaic panels and anaerobic digestion was designed for a source of clean energy for a Whisky Distillery located in the Andes in Peru. The proposed solution aims to contribute to the National Rural Electrification Plan and help Peru maintain the' pioneer in implementing renewable energy auctions' [1] status by providing electricity to this remotely located plant. The system proposal is based on the renewable energy resources available at the location - solar energy and waste generated from distillation processes. The plants' daily energy requirements (reaching 411kW) are to be supplied by the PV modules solely, and the AD system is treated as a backup energy source, which is due to be developed further. Chemical energy storage is introduced in the proposal. The next steps are undertaken by the distillery cover selling the excess energy back to the grid, estimated to bring an annual profit of £3700 and collaborate with the local community to supply the biogas. The payback period is estimated to 4 to 6 years. The system is estimated to save approximately 208 tons of carbon dioxide in its lifetime.

NOMENCLATURE

PV P DOD SOC kWp conditions) Pnom SD MPPT AD LCE

Photovoltaics Power Depth of Discharge State of charge Kilowatt peak (solar panels rating for peak performance under optimal Nominal Power Sunshine Duration Maximum Power Point Tracking Anaerobic Digestion Life Cycle Emissions

TABLE OF CONTENTS ABSTRACT ...................................................................................................................................................... 2 1- INTRODUCTION ......................................................................................................................................... 3 2- ENERGY NEEDS ........................................................................................................................................ 2 3- AVAILABLE RESOURCES ............................................................................................................................. 3.1- WIND ENERGY .......................................................................................................................................... 3 3.2- SOLAR ENERGY ........................................................................................................................................ 3 3.2- HEAT AND WASTE RECOVERY .................................................................................................................... 4 4- SYSTEM DESIGN ....................................................................................................................................... 4 4.1- SYSTEM DESIGN SIMULATIONS ................................................................................................................... 4 4.2- CARBON BALANCE .................................................................................................................................... 8 4.3- HEAT AND RECOVERY ENERGY GENERATION .............................................................................................. 7 4.4- ADVANTAGES AND LIMITATIONS ................................................................................................................. 8 5- ECONOMIC ASSESSMENT .......................................................................................................................... 8 6- CONCLUSIONS ......................................................................................................................................... 9 7- REFERENCES ..........................................................................................ERROR! BOOKMARK NOT DEFINED. 7.1- APPENDIX A: WORKING FILES.................................................................................................................. 11 7.2- APPENDIX B: GROUP MEMBER ASSESSMENT ............................................................................................ 18 7.3- APPENDIX C: GROUP MEMBER ASSESSMENT ............................................................................................ 18

1- INTRODUCTION The proposed site for the distillery is to be located adjacent to a mountain lodge in the Cordillera Blanca mountain range of the Peruvian Andes. Llanganuco Lodge is used by trekkers, climbers and tourists. This lodge has been in operation for several years and is run by an English ex-pat who is embedded into the local community. The site is remote, on the edge of the Huascaran National Park, at an altitude of 3500m. This brings challenges and opportunities that we shall look at in the energy needs section. Alex James is the owner of London to Lima Gin and is looking to branch out into whisky. As the draw of the Scottish Highlands creates a certain mystique about Scotch Whisky as such the High Peruvian Andes has similar potential. Making single malt whisky involves three raw materials: water, yeast and malted barley. Normally a distillery will outsource malting their barley and for this report this process will not be included although may draw an energy requirement in the future. In the mashing process malted barley is milled and mixed with hot water for the enzymes present in the malt to convert the starches into fermentable sugars. The solution of soluble sugars and water are then drained off, cooled and past to fermentation tanks, where yeast is added and the fermentation process beings. Once fermentation is complete, the wort is distilled, an energy intensive process, in a wash still normally over 4 to 8 hours and then past to the spirit still for further distillation over 8 hours or more. The product is new make spirit, which is then matured in oak casks. Figure 1 summarises the process.(2013)

Figure 1 The Basic Process of Whisky Making

The challenge is to calculate the energy need, find the most appropriate renewable energy solution and identify areas for waste and heat recovery.

2- ENERGY REQUIREMENTS The distillery's energy demand is based on the distillation processes' daily power consumption, electric means such as fans and pumps, and lighting usage. The primary energy requirements come from the distilling cycle, based on an 8-hour five-day workweek. The process covers mashing cycles, wash distillation, and spirit distillation, where every second mashing cycle is followed by one wash distillation and then one spirit distillation. Due to the high heat demanding nature of the process, there is a plan to implement direct electrical heating elements. The mashing process, wash, and spirit distillation has the following power requirements: up to 26.67kW, 74kW, 36.84kW, respectively. The cycle starts at 8:00 am, where the preparation for both the wash and spirit processes takes place until reaching the peak load of 65.2kW at 1:00 am. The load decreases gradually until 5:00 pm. Outside the working hours, the power need does not exceed 200W, which is used for the lighting system and safety battery ventilation (if required). The total daily electricity demand reaches 411 kWh; thus, the yearly consumption comes up to 107.68 MWh. Data gathered is computed into daily and annual profiles shown in fig 2 and 3. Due to the repeatability of the processes and their allocated time slots, the yearly energy consumption creates a steady profile dependable on the numbers of days in each month.

Due to the high altitude of the place, there is an energy saving of approximately 5% in the distillation cycle. The reason for this is the reduction in boiling temperature. At 3500m, water boils at 88 ℃ instead of 100℃. The energy saved estimated for this heat recovery system is 10%.

70 60 50 40 30 20 10 0

Yearly Electricity Demand

65.15875

63.63875

55.50875 44.18875 40.73875

40.48875

38.4887538.48875

22.10875 2.19875

8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 TIME (H)

Figure 2 Distillery Total Daily Power Demand (kW)

ELECTRICITY DEMAND (KWH)

POWER DEMAND (KW)

Total Daily Power Demand 9200 9000 8800 8600 8400 8200

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 3 Distillery Yearly Electricity Demand (kWh)

3- RESOURCES AVAILABLE 3.1- WIND ENERGY Wind is a prominent renewable energy source, yet it is very location-dependent. Despite the high attitude of the project, it has been found that the site has little potential to establish a wind farm. The estimated average wind speed ranges between 3.5-4.5 m/s, being much lower than the effective wind speed range required to run a turbine (3 - 25m/s). [2] 3.2- SOLAR ENERGY The studies revealed the considerable solar potential of the site, beneficial for implementing a Photovoltaic power system. The average yearly duration of sunshine at the place reaches approximately 4h/day, and the average daily irradiance reaches up to 10 kWh/m2 [figure:15]. Months from July to October have the largest insolation throughout the year, with September being the highest of about 238 kWh/m2. Yet, the sunshine is hugely affected by the precipitation trend (see graph 6, appendix), which create a vast difference between the actual sunshine duration and the astronomical SD. Figure 4 shows the global and diffuse radiation available at the place. The ambient temperature estimated at the area ranges from 9 to 14 °C, which is under the nominal operating cell temperature (20℃). This low temperature might have a slight negative impact on the efficiency of PV modules but less impact compared to high heat climate temperatures (> 40°C).

Figure 5 Yearly Radiation of the Site (kWh/m2), source: Meteonorm

Figure 4 Sunshine Duration at the Site (h), source: Meteonorm

3.3- HEAT AND WASTE RECOVERY A distillery offers many opportunities for energy recovery and waste reuse. The two main vectors to be studied are on the one hand the fatal heat created during the distillation process and on the other hand the residual organic waste.

Figure 6 Co – products generation during Scotch malt production process. (Akuna and Walker, 2016 [3])

These include the liquid residues "pot ale" and "spent lees" from the wash still and spirit still processes, as well as the waste from ground malt grains known as "draff". They each represent respectively 194, 69 and 48 tons or products per year. Globally, grains are often transformed in cattle food, but the liquid co-products are rarely reused. Hot liquids are simply cooled in shell and tube or worm tube condensers. However, these products could have many uses. Several ways of integrating this waste into circular reuse are being considered, such as generating biogas with anaerobic digestion or bioethanol, using the grains as solid biomass fuel or cattle feed and biochar, and finally, electricity generation with an organic Rankine cycle.

4- SYSTEM DESIGN 1- DESIGN CONSIDERATIONS The project site lies in the isolated area with the nearest grid line being 10km away from it; there is no definite electricity trading scheme existing nearby. For this reason, a stand-alone (off-grid) system will be the most suitable for the distillery. After a thorough analysis of the resources available, it has been decided to design a PV system coupled with an anaerobic digestion process. The PV modules will provide the primary source of

electricity to the site while utilising waste will help to supplement any missing energy and work as a backup source.

Figure 7 System Design, PV Modules combined with Anaerobic Digestion

4.2 - SOLAR SYSTEM The photovoltaic system was designed using PVsyst Software; the simulation was run multiple times to estimate the optimal output. The geographical data was set to latitude of -9.10° S, the longitude of -77.70° W, and the altitude at 3890 m. A seasonal tilt adjustment (winter tilt at 33°, summer tilt at 2°) was decided to be the most optimal, being a compromised solution between the fixed and the tracking axis one. The meteorological data were obtained using Meteonorm Software. The PV system consists of 165 monocrystalline panels, chosen due to their high rated efficiency (20%) and low maintenance costs. The model selected is the PowerSun, with a nominal power of 440Wp and 61V. The total array power reaches 66 kWp and requires 357 m2 of area for the modules mounted 11 in series and 15 in parallel strings.

Figure 8 Yearly Optimum Tilt Angle, PVsyst Software

Fig 9 presents the findings obtained after running the PVsyst simulation.

Figure 9:

Energy Balances Breakdown, PVsyst Software

Figure 10 PV System Performance, PVsyst Software

Performance Ratio is the ratio of the energy effectively produced (used) to the energy which would be produced if the system was continuously working at its theoretical STC efficiency. The system performance ratio (Fig 10) is averaged at (58%), which is determined by several reasons. Firstly, not all the produced energy by the PV array is being used and stored all the time. Some of the energy produced is lost when the battery is full of charge and there is no demand. Secondly, the orientation and tilt of the modules might not be at their optimum all the time. Secondly, climate changes might occur during winter months (high precipitation), and partial shading is caused by nearby objects and terrain. Additionally, the installed capacity is designed to meet the peak power demand of 65.2 kW; however, this high energy requirement is needed for approximately two hours during the day. As a result, the loss of energy during a day equals to 1.48 kWh/kWp/day. The collection losses of the modules are estimated at 1.18 kWh/kWp/day; these are caused due to the differences between the cell operating temperature and their STC conditions. Also, dirt on the PV modules, partial shading, mismatch losses, and incidence angle modifier of the front glass “IAM” contribute to the collection losses. Furthermore, the system losses of 0.55 kWh/kWp/day, include losses from batteries charging and electrical equipment’s efficiencies, inverter, and wiring.

The solar fraction, SolFrac, indicates the amount of energy supplied by the solar panel divided by the energy needs. For this system design, it is 98.33%, meaning it covers almost all energy demands, excluding 1.67% of the user's total energy need, which can be readily supplemented through the AD generator. The high voltage system was chosen to lower the cost of wiring and the solar charge controller. The charge controller is usually rated in Amp; therefore higher voltage system means lower cost of solar charger controller as well as maximizing the wattage of PV panels connected to one solar charge controller. Yet, the downside of using a higher voltage battery is safety and lack of options compared to lower voltage systems. Note that a stepdown voltage converter will be needed to run some appliances. 4.3- HEAT AND RECOVERY ENERGY GENERATION The different solutions enumerated in section 3.3 have been studied. Most of them presented different ranges of drawbacks. Using spent grains as cattle feed or biochar, turning them to bioethanol or as a fuel necessitate an extra input of heat to dry them, and sometimes some chemical transformation. A simulation has been studied with a French organic Rankine cycle producer, but it turned out that we didn’t have enough flow rate to produce in a profitable way. [3],[4],[5],[6],[7],[10] After these different primary studies, the solution finally chosen was the use of anaerobic digestion to create biogas. This biogas would then be combusted in a boiler to create heat, useful for distillation. The method is particularly adapted to distilleries for the case of pot ale liquid products. Indeed, the AD operates at a temperature of between 40 to 60°C. As these liquids are already hot (90°C), the conversion efficiency into biogas is improved, as the external heat input can be suppressed. The aim is then to reduce the transport time of the liquids as much as possible before they are incorporated into the digester. Another trick is to partially bury the tanks in the ground in order to improve the thermal insulation. The use of draff grains and spent lees is however less recommended in this process as this requires a much longer digestion time (3x) again due to the presence of lignin for spent grains and high water contain for spent lees. Appendix figure 28 shows the stages of AD. The biogas resulting from this process is mainly composed of methane (CH4), carbon dioxide (CO2) and water. Various molecules are also present, in particular hydrogen sulphide (H2S), which must be contained in very small quantities for health reasons. Depending on the case, the proportions of CH4 / CO2 produced in this process vary between 50-45 and 75-25. The biogas produced by distillery co-products generally has a ratio of 60-40%. [3],[8],[9],[11] The production calculations we were able to estimate gave us an annual production of 2904 m3 of biogas, which represents 15941 kwh of energy when burned in a boiler for producing heat. The data necessary for these calculations have been grouped Appendix figure 29. The production of biogas by anaerobic digestion would therefore be stored in some flexible storage membranes. It was decided that this energy was only a backup solution. The utility of this storage is then to punctually support the batteries in case of periods with insufficient PV electricity production (climate conditions, maintenance, extra-ordinary energy consumption). 4.4 – SYSTEM STORAGE A chemical storage system is proposed as a primary back up energy source due to its reliability and popularity in stand-alone PV systems. The proposal consists of 8 units of Li-Ion batteries (LG Chem. Rack R800) with a capacity of 64Ah, voltage of 725V and the loss of probability set at 2%. The Li-Ion were chosen due to their high charge/discharge efficiencies and relatively high specific energies, therefore very useful for the systems located in remote locations. The design considers one day of autonomy and the energy stored in the batteries would be released in periods of low sunshine, in case of increased electricity demand, or case of failure and maintenance activities of the PV modules. As the PV modules are designed to supply 98.3% of the electricity demand, the batteries would be charged daily from the surplus of the energy generated to act as a balance of system “BOS”. It is worth mentioning that meeting 100% of total energy demand would require heavy investment and oversizing of the PV and batteries. Finally, the depth of discharge is set to 10%-35%. So, the battery will be discharged until SOC 10% where the load is disconnected. Then the load will be again connected when SOC reached minimum of 35%. The following

this measure will help maintain the batteries' long lifespan and maximize the number of discharge cycles (less state of wear). One day of autonomy is a short period. However, it is unlikely that all the solar panels would stop working simultaneously, or the shadow will cover all of them. Due to the high costs of batteries and their maintenance, their number is kept at the lowest possible level to formulate a baseline scenario for future optimization for batteries cost effectiveness analysis.

4.5- ENVIRONMENTAL IMPACT - CARBON BALANCE

Figure 11 Carbon Balance of the PV System, PVsyst Software

The carbon balance analysis was conducted to estimate the amount of reduction in CO2 emissions if solar energy is implemented. The analysis was based on the comparison between the life cycle carbon emissions between conventional grid connected scenario and PV system to produce the same amount of electricity. The analysis was run in PVsyst software [figure 25]. The results indicate that the total amount of saved CO2 emissions of 731 tons, reaching a net carbon balance compared to grid emissions within 3 years of operation. Note that the calculations estimated the grey energy use of transportation and didn’t include the embodied emissions from maintenance and dismantling at the end of the lifetime. [12] 4.6- ADVANTAGES AND LIMITATIONS Instead of using a fossil fuel powered generator to run the distillery, The PV system coupled with AD heat recovery backup system set a cornerstone to install such a system to other nearby local communities. The project can be connected to the grid in the future using smart metering and utilize the energy loss in standalone type systems. 5- ECONOMIC ASSESSMENT In order to calculate the economics for the process, the comparison was made to electricity from the local grid, hence a per kWh price of £0.1 [13], it is important to note that the economic analysis was created around an already constructed process. The capital cost is the initial cost that must be accumulated at the start of the project, this cost covers the equipment (panels, invertors, batteries etc) and the installation cost, these are known as direct costs. As prices found in Peru were unreliable prices from the UK were taken and a 15% surplus was added to accommodate any price fluctuations. Capital cost can usually be reduced by government grants and incentives for renewable energy projects; however, Peru’s government has no such opportunities, hence this could not be considered and used as an offset. The capital cost is shown in appendix 5.1. As prices found in Peru were unreliable prices from the UK were taken and a 15% surplus was added to accommodate any price fluctuations. Capital cost can usually be reduced by government grants and incentives for renewable energy projects; however Peru’s government has no such opportunities, hence this could not be

considered and used as an offset. The capital cost is shown in appendix 5.1. The working files show all the calculations used. A sensitivity analysis was conducted on the net cash flow for the panels was concluded for ±20% the payback period was found to be 5-7 years. 6- CONCLUSIONS After determining the power drawn by the distillery and the corresponding amount of energy (107.68 MWh, annually), we designed a stand-alone solution to produce 100% renewable electricity. The most promising natural resource was solar irradiation in view of the geographical location and the surrounding environment. We therefore set up a battery power supply and electricity generation with photovoltaic solar panels. Numerous ways of circular development and waste recycling have been studied. The most appropriate solution to our problem is the generation of biogas in anaerobic digestion from the distillery's co-products. The solar panels represent a surface area of 330 m2 made up of 14 rows of 11 modules with a nominal 440 Wp. The batteries will be 6 in number and will be able to meet the peak daily consumption of 65.2 kW. Their autonomy under load and without power supply is estimated at 1 day with a capacity of 64 Ah. The AD will be feed by the liquid pot ale co-product and will act as a backup solution. This stored biogas will allow us to support the batteries punctually on days of shortage by being burnt. The payback period of the solution presented is estimated between the fourth and sixth year, and the quantity of CO2 emitted into the atmosphere saved is estimated at 208 tons over 25 years. Several areas for improvement can be identified from the work carried out. These recommendations should be studied with a view to perfecting the solution devised in the first instance. Regarding the design of the batteries and solar panels, we could benefit from having the AD taking over when the DOD of the batteries falls below 70%. It would also be more profitable if the batteries had a 7-day autonomy. In the event of excess energy production, the introduction of the possibility of reselling green electricity to the local grid could generate 3700 pounds per year. Finally, it was agreed that the waste reuse solution could be much more profitable by setting up a local agricultural cooperative promoting a circular economy around each other's wastes (farmers, agriculturists, distillery).

7- REFERENCES

[1] IRENA, “Peru Renewables Readiness Assessment,” IRENA , 2014. [2] G. L. a. J. Zhi, “Analysis of Wind Power Characteristics,” China Electric Power Press., no. no. 5., 2016. [3] J. a. W. G. Akunna, “Co-products from malt whisky production and their utilisation,” vol. Ch 34., Dundee, (2016). [4] “Investigation of Energy Production from Distillery Co-Products for Balmenach Distillery,” Speyside, Scotland.. [5] N. C. J. a. B. N. Bhattrai, “Energy Recovery Potential from Spent Grains in Breweries of Nepal,” in Austrian Partnership Programme in Higher Education and Research for Development View project Energy Recovery Spent Grains in Breweries of Nepal, 2017, pp. 93-97. [6] A. P. C. a. F. R. Connolly, “Characterisation of protein-rich isolates and antioxidative phenolic extracts from pale and black brewers’ spent grain.,” International Journal of Food Science & Technology, vol. 48, no. 8, p. pp.1670–1681., 2013. [7] A. O. E. M. G. A. J. F. C. A. A. H. J. a. R. D. Osman, “Upcycling brewer’s spent grain waste into activated carbon and carbon nanotubes for energy and other applications.,” Journal of Chemical Technology & Biotechnology, vol. 95, no. 1, pp. 183-195, (2019).

[8] SGC, “ Basic data on biogas,” Vols. 2nd ed, Malmö., 2012. [9] W. Hamilton, “Anaerobic Digestion of Animal Manures: Understanding the Basic Processes - Oklahoma State University.,” Oklahoma State University, 2017. [Online]. Available: extension.okstate.edu. Available at: https://extension.okstate.edu/fact-sheets/anaerobic-digestion-of-animal-manures-und. [10] “www.esru.strath.ac.uk. (n.d.). Whisky Co-product Power Generation - Biofuel Production.,” [Online]. Available: [online] Available at: http://www.esru.strath.ac.uk/EandE/Web_sites/1011/Whisky/biofuel_production.html.. [11] “ www.esru.strath.ac.uk. (n.d.). Whisky Co-product Power Generation - Economic Tool - Biogas Boiler,” [Online]. Available: Available at: http://www.esru.strath.ac.uk/EandE/Web_sites/1011/Whisky/biogas_boiler.html.. [12] A. K. e. al, “PVSEC, 28th,” 2013. [13] “Peru - Countreis & Regions - IEA,” [Online]. Available: https://www.iea.org/countries/peru.

7.1- APPENDIX A: WORKING FILES

Figure 12 : Mean Power Density at Height 100m

Figure 13 Mean Power Density map at 100m [2]

Figure 14 Mean Wind Speed 3500m Height (source: Global wind Atlas)

Figure 13 Daily Global Radiation

Figure 16 Monthly Temperature Range

Figure 17: Daily Temperature Over a Year

Figure 18: Solar Declination of the Site

Figure 19 Global Radiation, South America

Figure 20 Global Incident in coll. Plane [kWh/m2.day]

Figure 21: Fixed Tilt Angle, Summer (PVSyst)

Figure 22: Fixed Tilt Angle, Winter (PVSyst)

Figure 23: Standalone Working Scheme

Figure 14 : Loss diagram over the year

Figure 24: Loss diagram over the year

Figure 25: carbon balance calculations

Figure 26: T-x-y Diagram for Ethanol-Water at sea level (101kPa)

Figure 27: T-x-y Diagram for Ethanol - Water at 3500m (66kPa)

Figure 28 Two Stage Pot Still Distillation Flow Diagram

Figure 29: Energy Requirements for Distillation Processes

Figure 30: Anaerobic Digestion Process (W. Hamilton, 2017)

Figure 31: Data Assumptions for Calculation, AD

Figure 32: Anaerobic Digestion Process (W. Hamilton, 2017)

7.2- APPENDIX B: ECONOMIC APPENDIX

Cash Flow (PV + 7 day backup) 300000 250000

Cash Flow (£)

200000 150000 100000 50000 0 0

-50000 -100000

Year Figure 33: Cash flow

Sensitivity Analysis 350000 300000 250000

Cash Flow (£)

200000 150000 100000 50000 0 0

-50000 -100000

Year Cash Flow (PV + 1 day backup)

(-20%)

(+20%)

Figure 34: Sensitivity analysis