Challenges and Opportunities of Soy-based Polyurethane Foam production
15022536 29 JANUARY 2016
CONTENTS
List of abbreviations
Abstract 1.
Introduction
2.
Background study of soy-based polyurethane foam
3.
Sustainability of acquisition of raw materials for the production of soy-based polyurethane foam
1.1 Background 1.2 Aims, Objectives & Method
2.1 2.2 2.3 2.4
3.1 3.2 3.3 3.4 3.5
Properties Environmental benefits of soy-based polyurethane foam Applications Market and Trend of Consumption
Life cycle chart Global production of soybean Key challenges of acquisition of raw materials 3.3.1 Fossil fuel-dependent agricultural system 3.3.2 Greenhouse gas emissions, pollution and biodiversity loss from agriculture Steps towards responsible soy 3.4.1 Energy efficiency 3.4.2 Organic farming 3.4.3 Genetically-modified crops Threats to the soy crop industry 3.5.1 Impacts of climate change on agriculture 3.5.2 Agricultural land competition with food/feedstock
4. Conclusion
References
2
LIST OF ABBREVIATIONS CFC
Chlorofluorocarbon
GHG
Greenhouse gas
GM
Genetically modified
HCFC
Hydrochlorofluorocarbon
IEA
International Energy Agency
IPCC
Intergovernmental Panel on Climate Change
IPM
Integrated Pest Management
LCA
Life cycle analysis
PU
Polyurethane
SIP
Structural insulated panel
USDA
US Department of Agriculture
USSEC
U.S. Soybean Export Council
VOC
Volatile organic compounds
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ABSTRACT Polyurethanes (PU) are one of the most versatile and widely-used polymers in various industries. The rigid polyurethane foam is an effective thermal insulation derived primarily from non-renewable fossil fuels. Increasing concerns over the depletion of fossil fuels and climate change have led to considerable efforts to substitute petrochemicals with biomass derivatives in PU. Soy-based PU has been proven to be more environmental-friendly than its petroleum-based counterpart through the use of renewable materials, CO2 sequestration through photosynthesis and its biodegradability. This report reviews the sustainability of the materials acquisition stage in the life cycle of soy-based PU foam to justify its wider application as a more feasible alternative in polyurethane insulation. Keywords: Polyurethane, soy-based, petroleum-based, biodegradable, renewable, sustainability
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1
INTRODUCTION 1.1 Background The building sector accounts for approximately 32% of global energy use and almost 10% of total direct energy-related CO2 emissions.(IEA, 2012) The IPCC (2007) projected that building-related greenhouse gas (GHG) emissions reached 8.6 billion metric tons CO2 equivalent in 2004, and expected to grow to 15.6 billion metric tons CO2 by 2030 under their high-growth scenario. Other sectors 4%
Transport 30% Buildings 35% Industry 31%
Figure A : Final Energy Consumption by Sector and Buildings Energy Mix, 2010 (IEA, 2013)
Moreover, the world’s primary energy resources - coal, oil and natural gas, are facing depletion. The production of fossil fuels over time follows a bell shaped curve, as depicted in Figure B. The high quality, cheaper resource is produced first
Peak production - the production of fossil fuels becomes more energy intensive due to declining resources.
Figure B : Known and projected production of all hydrocarbons from 1930-2050 (Campbell, 2004)
Figure C : Proved Reserves of Fossil Fuels (Knoema, 2015)
As the production of conventional hydrocarbons declines, the world will use non-conventional sources, which are more expensive. The transition from conventional oil to substitute sources of energy is likely to have major economic, environmental and security implications. (Sorrell, Speirs, Bentley, Brandt and Miller, 2009) In this case, if demand does not fall in parallel, severe world resources shortages are inevitable.
Figure D : Fossil Fuels – Estimated years of extraction remaining (Knoema, 2015)
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Escalating concerns about climate change and rapid depletion of fossil fuels have led to the development of bio-based construction materials. Bio-based materials are derived from natural, renewable sources and are biodegradable. The soy-based PU is a popular alternative to petroleum-based PU, commonly used in building insulation foam. Soy-based PU is partly manufactured from soy by-products, thus reducing the dependence on fossil fuels and mitigating GHG emissions.
1.2 Aims, Objectives & Method In order to justify the sustainability of soy-based PU insulation as a greener alternative to petroleum-based PU insulation in the built industry, this report is structured into two components: (a)
A comparative analysis of the properties and applications of soy-based PU and petroleum-based PU
(b)
An evaluation of the key challenges of the materials acquisition stage in the soy-based PU life cycle and opportunities to improve its sustainability
The analyses are supported by secondary research sources such as academic journals, books, magazine articles and grey data.
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2
Background study of soy-based polyurethane foam 2.1 Properties 2.1.1 Chemical Properties Properties
Petroleum-based polyurethane foam
Soy-based polyurethane foam
Chemical formula
Figure E : Chemical formula of polyurethane (Wang, 2006) Mixture of polyisocyanate and soy-based polyol (oil extracted from soy bean and replaces the polyol component of polyurethane – highlighted in red)
Main Components
Made by the exothermic reaction (heat emitted) of a polyisocyanate (-NCO) group and a petroleum polyol group (-OH). Polyether polyols and polyester polyols are two major polyols in the market.
Additional Components
Additives include catalysts, blowing agents, surfactants, pigments, fillers, flame retardants, smoke suppressers and plasticizers. Usually added in small quantities – typically less than 1 to 2%. (Boustead, 2005)
Blowing agents to create polyurethane as a foam
Chemical blowing method uses water. Physical blowing method uses pentane (hydrocarbon), CFC (Chlorofluorocarbon), HFC (Hydrofluorocarbon) or CO2 (carbon dioxide) Spray foams emit VOC (volatile organic compounds)
Water CO2 – non-reactive, non-flammable and non-explosive. Does not contain urea, ozone depleting agents or formaldehyde. No toxic gas emissions
Table 1 : Comparative Analysis of the chemical properties of soy-based PU and petroleum-based PU
2.1.2 Forms Petroleum-based and soy-based PU insulation foams exist in closed-cell and open-cell forms. Form
Open-cell foam
Closed-cell foam
Description
The cell walls, or surfaces of the bubbles, are broken and air fills all of the spaces in the material. It has lower strength and rigidity compared to closed-cell foam. (PU Europe, n.d.)
Densely packed foam with unbroken bubbles. Adds structural strength to certain load-bearing building elements. Improves air tightness of building. More suitable for cold climates.
Blowing agent
CO2 , water
Physical blowing agent : Hydrofluoroalkanes, water
Typical density, lb/ft3
~0.5
~2.0
R-value, per inch
3.4-3.8, Open-cell foam cells are not as dense and are filled with air, which gives the insulation a spongy texture and a lower R-value.(Office of Energy Efficiency & Renewable Energy, n.d.)
6.0-7.0
Cost
More expensive because it requires more materials to support its weight.
Table 2 : Comparative Analysis of the open-cell foam and closed-cell foam of PU 7
2.1.3 Mechanical properties & After-Life Properties Basic properties
Petroleum-based polyurethane foam
Soy-based polyurethane foam
Thermal performance
Closed cell rigid foam : R-6.5 per inch Open cell liquid foam : R-3.6 per inch
Heat resistance
Depending on the density and type of facings, rigid polyurethane insulation for building applications can be used long-term over a temperature range of -30°C to +90°C.(PU Europe, 2014)
Moisture permeability
Closed cell foam has lower water vapour permeability than open-cell foam
Mechanical performance
Depending on the density, typical tensile stress values: 40 – 900 kPa, and shear strengths values: 120 – 450 kPa.(PU Europe, 2014) For density of 30 kg/m3, typical values of compressive strength: 100-150 kPa. (Oertel, 1994)
Based on a research from the University of Toronto (Gu, Konar and Sain, 2012) , the properties of soy-based PU foams (in comparison to petroleum-based PU foams) are: - Higher T(g) (glass transition temperature) - Worse cryogenic properties - Lower thermal degradation temperatures in the urethane degradation - Good thermal degradation at a high temperatures - High hydroxyl value soy-based polyol has superior tensile, higher elongation, lower compressive strength and modulus, small and better distributed cell size than low hydroxyl value soy-based polyol
Fire performance
Rigid polyurethane foam is combustible. Its ignitability and rate of burning can be modified according to building applications.
Density
Lifespan
Another research from the University of Minnesota and Cargill (Tan, 2010) shows that soy foams : The density of rigid polyurethane foam used for - Aged much faster thermal insulation in buildings normally ranges - Have comparable density and initial thermal conductivity between 30 kg/m³ and 45 kg/m³. However, it - Much higher Tg and compressive strength can reach 100 kg/m³ for some applications. - Smaller average cell size (BING, 2006) Depending on the application, the lifespan of polyurethane is : - 50+ years for building insulation - 25+ years for refrigerators - 20+ years for car bumpers
Waste Degradability PUs made from polyether polyols are relatively management resistant to microbial degradation, whereas the polyester polyols are more vulnerable to biodegradation processes.(Darby and Kaplan, 1968) Recyclability
In conclusion, both research show that soy-based PU foams display mechanical and thermal properties comparable to that of petroleum-based PU foams. Biodegrades when disposed of
All polyurethanes can be recycled. However, the recycling process is energy-intensive. In the EU, energy recovery is achieved through clean and careful incineration, whereby pollutants are filtered out and energy is produced as a result of the combustion process. PU foams also end up in landfills.
Table 3 : Comparative Analysis of the mechanical and after-life properties of soy-based PU and petroleum-based PU
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2.2 Environmental Benefits of soy-based PU Soy-based PU offers significant advantages over petroleum-based PU in regard to sustainability, reduction of petrochemical contents and potential lower cost. Because soybean oil is a renewable resource, abundant particularly in the U.S., and relatively low in cost, it has become an alternative source to produce polyols.(Tu, 2008) Each soy plant sequesters approximately 2 pounds of CO2 for every pound of soy oil produced whereas petroleum polyols increase CO2 emissions by 3.5 pounds.(Pollack, 2006) The two life cycle analyses of soy-based polyol production developed by Cargill (Figure F) and The Dow Chemical Company (Figure G) show that soy-based polyol production has much lower environmental impacts than petroleum-based polyol production.
Figure F : Comparison of the environmental footprint between petro-based polyol and BiOH® polyols developed by Cargill, based on the preliminary life cycle analysis by Five Winds International (Wazirzada,2009) Results of LCA Soy-based polyol contribute to : • 23% reduction in total energy demand • 61% reduction in non-renewable energy use • 36% less global warming emissions
Figure G : Comparative Life Cycle Analysis of Polyurethane Foam Production Process, by The Dow Chemical Company and APME (Dow Chemical Company,n.d.) Results of LCA • Production of polyols from soy requires half the total energy and only one-third of the fossil fuel resources of those consumed in petroleum polyol production • Soy-based production has no net GHG emissions
2.3 Applications In the construction industry, PU foam is applied as a liquid sprayed foam or rigid foam board. PU is widely used as the insulation core in structural insulated panels (SIPs). Soy-based, PU liquid spray-foam offers a more sustainable option as the insulation core of SIP, with a cured R-value of 3.5 per inch.(Office of Energy Efficiency & Renewable Energy, n.d.) Interior Sheathing Exterior Sheathing
Insulation Core Types: - Liquid foam (sprayed/foamed in place) - Foam board *Liquid foam is usually cheaper than installing foam boards. Liquid foam performs better because the it moulds itself to all of the surfaces
Petrochemical-based foam insulation Molded expanded polystyrene (EPS) Extruded polystyrene foam (XPS) Polystyrene (PS) Polyisocyanurate foam Polyurethane foam (PUR) Soy-based foam insulation
Figure H : Structural Insulated Panel
Polyurethane foam insulation is also used in insulated metal panels for roofing and wall cladding. The spray foam seals cracks and crevices in doors and windows in construction. PU foam is also used to insulate heating and plumbing services in municipal heating pipes and offshore oil and gas pipelines. 9
2.4 Market and Trend of Consumption 2.4.1 Petroleum-based PU foam market Polyurethane (PU) is the most widely used polymer in the world. The global PU foam market was about $46.8 billion in 2014 and is estimated to reach $72.2 billion in revenue by 2020. (Markets and markets, 2015)
Figure I : Global polyurethane market estimates and forecast, by product, 2012-2020 (kilotonnes) (Grand View Research,2014)
2.4.2 Soy-based PU foam market
Construction
Building insulation, refrigerated buildings, walk-in cooler insulation, molded millwork, laminated insulation board stock, insulated doors and metal panels.
Transportation
Automotive vehicle and farm equipment component cushioning.
Carpet
Flexible foam attached cushion and fiber binder coatings.
Furniture and Bedding
Flexible foam cushioning applications.
Coatings, Adhesives, Sealants
Window seals, industrial adhesives and protective coatings.
Binders
Rubber and wood products.
Figure J: Six market segments for soy-based polyurethane (USB, 2012)
There has been a major positive shift towards green and bio-based PU foam market as global polyurethane demand increases. The consumption of polyurethane rigid foams made from green & bio polyols is expected to increase from 456.8 kilotons by 2018.(Markets and markets, 2014) Soy-based polyols can now replace as much as 50% of petroleum-based polyols in rigid polyurethane foams without obvious property changes (Tu, Suppes and Hsieh, 2008). The soy-based polyurethane market is increasingly getting attention from researchers and companies, especially in the U.S.
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The table below summarises the key companies currently investing in soy-based polyols and polyurethane development. Trade name
Company
Country
Soybean oil (GMO & conventional) Prolia™ soy flour Agri-Pure Gold™ 414 BiOH® polyols and polymers
Cargill Inc.
USA
RENUVA™ Technology
The Dow Chemical Company
USA
Agrol Prime (TM) Agrol® AO
Biobased Technologies®
USA
Vikoflex® 7170 Epoxidized Soybean Oil
Arkema Inc.
France
Sovermol® polyols EMEROX® Renewable Polyols InfiGreen® Recycle Content Polyols InfiGreen® Polyols
Cognis Oleochemicals (renamed Emery Oleochemicals in 2008)
Malaysia, Thailand
SoyolTM R2 polyol, SoyolTM R3 polyol
Urethane Soy Systems
USA
Soy SealTM , soy based spray polyurethane foam insulation
BioBased Insulation
Ireland
Merginol®
Hobum Oleochemicals
Germany
Radiar®, Radiar®7291, Radiar®7292, Radiar®7293
Oleon (Sofiproteol)
Belgium
Baydur Pul 2500
Bayer
Germany
JEFFADDTM B650
Huntsman Corporation
USA
Table 4 : Trade names and suppliers of commercially-available soy polyols for the production of soy-based polyurethane
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Sustainability of acquisition of raw materials for the production of soy-based PU foam The decline of petroleum supplies, increasing GHG emissions and the lack of degradability of petroleum-based PU foams have led to the development of PU foam from renewable sources that can meet cost and performance requirements of the market. Due to the limited choice of isocyanates, a majority of the research on renewable substitutes is focused on the polyol component in the PU derived from soybeans. This chapter discusses the key challenges and opportunities of the acquisition stage of the soy-based PU life cycle. A major question arises from this discussion – to what extent does soy-based PU consumption contribute to significant petroleum savings and environmental benefits given that the agricultural production of soybean is fossil-fuel driven?
3.1
Life cycle chart
To analyse the environmental impact of soy based foam insulation, it is important to understand the key stages in its life cycle.
Raw material acquisition & preproduction
Manufacturing of polyurethane
- Extraction of petroleum - Processing of polyurethane components
Packaging & Distribution - Transportation - Storage
Consumer Use - Indoor health - Toxic VOC released from product
End-of-life - Landfill - Incineration - Recycling
Figure K : A petroleum-based polyurethane foam product life-cycle STAGE 1 Raw material acquisition & preproduction - Cultivating soybean - Harvesting - Processing (oil extraction) - Processing of polyurethane components
Manufacturing of soy-based polyurethane
Packaging & Distribution - Transportation - Storage
Consumer Use
End-of-life - Decomposition - Landfill
Figure L : A soy-based polyurethane foam product life-cycle
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Chemical & Food industries
Soy meal
Land clearing to create soy farms
Soy bean cultivation
Harvest & Storage Seeds removed from pods and dried if moisture content >14% (USSEC, 2006)
Crushing & Extraction of oils from soybean
Methods: 1. Pressing 2. Organic solvent (hexane) 3. Enzyme treatment
Soy oil
Refinery & Processing
Fossil fuel Extraction & Processing
Polyols production
Polyols transport
Diisocyanates production
Diisocyanates transport
Other materials production :
Other materials transport
Soy-based polyurethane production
Eg : surfactants, catalysts, pigments, blowing agents
Figure M : Schematic flow chart for the production of soy-based polyurethane foam – STAGE 1 of the life cycle
3.2
Global production of soybean
Today, the world’s top producers of soy are the United States, Brazil, Argentina and China (Figure N). The lack of available farmland is a long-term constraint in the EU to produce biomass crops sufficient to meet the huge energy requirements (USDA, 2006) On the other hand, Brazil has massive growth potential in agriculture due to the availability of virgin lands.
Figure N : Major soybean producing countries worldwide in 2014/2015 (million metric tons) (USDA, 2016)
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Soybeans
Conversion level
Crushed
Whole Beans
(85%)
Step 1
Other Applications
Hull Products
Step 2
Edible Oils, Margarine, Spreads (95%)
Step 3
Toner Polymer
Coating Resin
(15%)
Extracted Crude Oil
Extracted Meal
Biofuel
Bioproducts
Plasticizer
Soy-based polyol
Step 4
PU foam
Toasted
Animal Feed
Poultry
Other Food Products
Beef
Bones, Skins & Offal
Fermented
Pork
Meat Products
Soysauce
Eggs
Milk Production
Egg Products
Dairy Products
Figure O : Products derived from soybean (adapted from WWF, Soyatech and Soy Ohio)
3.3
Key challenges in acquisition of raw materials
3.3.1 Fossil fuel dependent agricultural system The agricultural system is dependent on non-renewable fossil fuel resources for direct or indirect energy. Research indicates that fertilizer and fuel are the primary energy inputs for a soybean production system. (Rathke, Weinhold, Wilheim and Diepenbrock, 2007) Direct energy is consumed in activities such as field operations, processing, packaging and transportation of agricultural materials. By the 1990s, diesel engines became the primary engines in agriculture. Diesel fuel contains a high energy per litre (36.4 MJ/litre) (ORNL, 2008) , diesel engines deliver more mechanical energy per MJ of input (Cleveland, 1995) , and diesel engines have a long life span due to fewer moving parts. Irrigated crops require large quantities of water and enormous amounts of fossil energy for pumping and applying the water. On average, soybeans require about 5.8 million liters/ha of water for a yield of 3 t/ ha.(Magdoff and Tokar, 2010) In areas such as Argentina where rain does not provide adequate water supplies, irrigation is important for growth of crops. Indirect energy is the energy required to manufacture inputs such as fertilizers and pesticides. The studies conducted by University of Nebraska (IPNI, 2012) shows that soybeans obtain 50 to 60% of their nitrogen (N) nutrition from group H rhizobia soil bacteria fixation. The remainder comes from residual and mineralized N in the soil. There is no general need for nitrogen fertilizer when soybean roots are well inoculated with group H rhizobia. (Oldham and Crouse,2011) Figure P shows that in high-yielding environments of over 60 bu/acre, fixed N and soil N are not sufficient to meet the N demands of the plant, therefore additional N fertilization is required. Besides nitrogenous fertilizers, phosphate and potash fertilization are required for soybean production to achieve maximum yield.
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Soybean yields (bu/acre)
Additional N needed (from fertilizers) (lb N/acre)
50 – 60
0, except in soils with very low inherent N mineralization (low organic matter)
60 – 80
0 – 30 In soils with high mineralization capability, N may be sufficient
80 – 100
30 – 60
> 100
> 60
Figure P/Table 5 : Nitrogen needs of soybean based on N Budget (Schmidt, n.d.)
3.3.2 Greenhouse gas emissions, pollution and biodiversity loss from agriculture Net global GHG emissions from agriculture, forestry, and other land use were over 8 billion metric tons of CO2 (FAO, 2014) equivalent to 24% of total global GHG emissions.(IPCC, 2014) CO2 is emitted by fossil fuels combustion to power farm machinery and transportation. Diesel-operated machinery produces 15% less CO2 than petrol, but emit four times more non-GHG nitrogen dioxide (NO2) pollution and 22 times more particulates (Vidal, 2015) Methane and nitrous oxide (N2O) are produced from biological decomposition processes and agricultural waste and land burning. Soy plantation also poses threats to the biodiversity of forests, savannahs and grassland. As shown in Figure R, soy cultivation takes up around 13-15 million ha (7%) of the Cerrado biome, which holds 5% of the world’s biodiversity and is an important South American water source. (WWF Brazil, 2012)
Figure Q : South American landscapes at risk from soy expansion (WWF, 2014)
Figure R: Increase in soybeans planted areas in Cerrado municipalities, 20012010 (WWF Brazil, 2012)
The application of synthetic fertilizers in soy plantation actively promotes soil degradation and pollution of watercourses from agrochemicals run-offs. Approximately 90% of U.S. agricultural lands are losing topsoil above sustainable rates (1t/ha/yr) due to erosion. (Gever, Kaufmann, Skole and Voeroesmarty, 1991) LCA of soy production in the Cerrado found annual soil erosion losses of 8 t/ha, compounded by loss of organic matter, compaction and acidification (Mattsson, Cederberg and Blix, 2000) . In Argentina, where there is less use of rhizobia inoculation, large off-site leakage of both nitrogen and phosphorus has been estimated from soybean crops (Pengue, 2005) with potential degradation of downstream water quality and aquatic ecosystems.
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3.4
Steps towards responsible soy
3.4.1 Energy efficiency Making the transition to low-carbon agriculture can significantly reduce environmental impacts of soy-based PU production. According to FAO(2011) , options to improve energy efficiency in the agricultural system include: • Application of freight truck fuel economy standards and payload limits • Minimum energy performance standards (MEPS) for machinery • Vehicle speed restrictions • Higher charges for landfill disposal of organic wastes • Substitute fossil fuels with renewable energy (solar, wind, hydro, geothermal, biomass). • Use residue materials for combined heat and power generation. • Irrigation monitoring and targeted water delivery. Photovoltaic irrigation pumps are a viable option to minimize energy use.
3.4.2 Organic farming Organic farming promotes three sources of nutrients that improve soil nutrient levels and reduce energy inputs from synthetic fertilizers. Organic sources of nutrients
Description
Manure
Manure provides nutrients in more stable forms than synthetic sources, which can prolong nutrient levels in production systems.
Legume production
Soybean plants are legumes which obtain their nitrogen mostly from the group H rhizobia bacteria on the nodules of its roots. The bacteria on the nodules absorb nitrogen from the air and fix it into the soil, which can then be used by other plants, making them beneficial for crop rotations. Crop rotations controls soil erosion, minimise pests, pathogens and weeds, as well as regulate soil nutrients use. In the U.S., soy and corn are planted in alternating years.
Crop residue
Crop residue incorporation helps to maintain land surface cover, stabilize soil structure and prevent nutrient loss during erosion. Like manure, crop residue provides long term nutrients.
Table 6 : Organic sources of nutrients (Cruse, 2009)
Also promoted in organic farming, Integrated Pest Management (IPM) is an approach to sustainable intensification of crop production, pesticide risk reduction and energy use efficiency. (FAO, 2016) IPM approaches to managing pest
Description
Biological control
Natural predators, parasites, pathogens, and competitors are used to control pests and their damage.
Cultural control
Pest establishment, reproduction, dispersal, and survival are reduced Eg : changing irrigation practices to reduce root disease and weeds that can lead to pest growth
Mechanical and physical control
Pests are eliminated directly or the environment is made unsuitable for it. Eg (mechanical) : Traps for rodents Eg (physical) : Mulches for weed management, steam sterilization of the soil for disease management, or barriers such as screens to keep birds or insects out.
Chemical control
Pesticides are selectively applied only when needed and in combination with other approaches for more effective, long-term control. Pesticides are used in bait stations rather than sprays; or spot-spraying a few weeds instead of an entire area.
Table 7 : IPM approaches to pest management (UC IPM, 2014)
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A farming trial study (Pimentel, Happerly, Hanson, Douds and Seidel, 2005) has proven that organic soy crop yields can equal those from conventional farming, but uses 30% less energy, less water and no pesticides. Organic farming also reduces runoff and soil erosion.
Table 8 : Energy inputs in a conventional soybean production system per hectare in the U.S. (Pimentel, 2006)
Table 9 : Energy inputs for a model organic soybean production system per hectare in the U.S. (Pimentel, 2006)
3.4.3 Genetically-modified soy crops In 2007, 58.6% of global soybean crops were GM.(Lerner, 2009) GM soybeans have higher resistance to pathogens and pests, and better adaptation to climate and geographic factors such as drought and salinity, which reduces dependence on chemicals needed for crop protection. An analysis by Brookes and Barfoot (2015) shows that GM biotechnology has led to increased yields independent of breeding. Besides contributing to lower pesticide and fuel use, GM crops practices conservation tillage that reduces soil erosion, improves carbon retention and lowers GHG emissions.
1996-2013 additional soybean production (million tonnes)
2013 additional soybean production (million tonnes)
138.20
15.94
Table 10 : Additional soybean crop production arising from positive yields effects of GM soy crops (Brookes, Barfoot, 2015)
3.1% -0.1%
-9.3%
2013
-14.5% Cumulative
% Change in amount of herbicide (active ingredient) used % Change in Environmental Impact Quotient (EIQ) Figure S : Reduction in herbicide use and the environmental load from using GM HT soybeans in all adopting countries 1996-2013 (Brookes, Barfoot, 2015) 17
3.5
Threats to the soy crop industry
3.5.1 Impacts of climate change on agriculture Increasing temperatures in tropical countries impedes photosynthesis and plant growth. Sea level rise as a result of global warming reduces potential agricultural land, particularly delta areas which are often the most fertile. Rainfall patterns will become more variable and storms more intense, leading to increasing crop failures. Conversely, Ziska (2009) found that the growth of GM soybeans is stimulated by elevated CO2 levels. However, this comes with a higher application of herbicides to control increased weed growth. 3.5.2 Agricultural land competition with food/feedstock The industrial production of crops for bio-based products has potential to induce global food insecurity. Diverse conflicts exist in the use of land, water, energy and other environmental resources for food, feedstock and bioproducts. Processed soybeans are the largest source of protein feed and second largest source of vegetable oil in the world.(USDA, 2006) Income growth in developing countries will lead to higher consumption of milk and meat products (FAO, 2011), which will increase the demand for livestock feed. In order to minimise land competition, it is crucial to rationalize the distribution of farm outputs for food, feed and fuel. Planting soy on degraded land rather than in newly cleared forest is a method of reducing new land competition and deforestation. Evidence shows that large areas of South America previously degraded by cattle have been converted to soy cultivated pastures. (WWF, 2014)
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Conclusion Alarming rates of fossil fuel depletion and climate change have led to the substitution of petrochemical polyols in polyurethane foam with renewable soy-based polyols. Soy-based PU offers significant advantages over petroleum-based PU in regard to biodegradability, reduction of petrochemical contents, carbon sequestration and potential lower cost. The evaluation of the materials acquisition stage in the life cycle of soy-based PU foam highlights key issues of the production of soy. Soy crops are grown and processed using fossil-fuel dependent agriculture system which emits significant amount of GHGs and impacts the natural ecosystem. Soy-based PU foam production may compete for agricultural land needed to grow food and feedstock. Therefore, an important goal in agriculture is to improve energy efficiency at all stages of the soy-based polyol production; to adopt organic farming methods and to implement efficient land use. The benefits of investing in more energy-efficient soy-based PU as an alternative to petroleum-based PU are large. So far, isocyanates in the PU foam market have not been made through a bio-based approach. (Gu, Sain, 2014) Coupled with efforts to improve the mechanical properties of bio-based PU, the research in the field of bio-based isocyanates could lead to a wider application of a 100% bio-based polyurethane foam in the construction industry.
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Text References
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Figure References
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Figure L Song PF., 2015, A soy-based polyurethane foam product life-cycle [Author’s own image] Figure M Song PF., 2015, Schematic flow chart for the production of soy-based polyurethane foam – STAGE 1 of the life cycle [Author’s own image] Figure N USDA, 2016, Major soybean producing countries worldwide in 2014/2015 (million metric tons). Available at http://www.usda.gov/oce/commodity/wasde/latest.pdf [Accessed 18 December 2015] Figure O Song PF., 2015, Products derived from soybean. [Author’s own image - information adapted from WWF, Soyatech and Soy Ohio] Available at http://wwf.panda.org/what_we_do/footprint/agriculture/soy/facts/, http://www.soyohio.org/council/investment/soy-bioproducts/ and http://www.soyatech.com/soy_facts.htm Figure P Schmidt J., n.d., Nitrogen needs of soybean based on N Budget, Available at https://www.pioneer.com/ home/site/us/agronomy/library/nitrogen-fertilizer-for-soybean/#fig1 [Accessed 15 December 2015] Figure Q WWF, 2014, South American landscapes at risk from soy expansion, Available at http://issuu.com/wwfsoyreport/docs/wwf_soy_report_final_jan_19/5?e=10667775/6569194 [Accessed 30 December 2015] Figure R WWF Brazil, 2012, Soy plantations in the Cerrado, Available at http://d3nehc6yl9qzo4.cloudfront.net/downloads/wwf_soy_cerrado_english.pdf [Accessed 30 December 2015] Figure S Brookes G., Barfoot P., 2015, Reduction in herbicide use and the environmental load from using GM HT soybeans in all adopting countries 1996-2013, Available at www.pgeconomics.co.uk/pdf/2015globalimpactstudyfinalMay2015.pdf [Accessed 30 December 2015]
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Tables
Table 1 Song PF., 2015, Comparative Analysis of the chemical properties of soy-based PU and petroleum-based PU Table 2 Song PF., 2015, Comparative Analysis of the open-cell foam and closed-cell foam of PU Table 3 Song PF., 2015, Comparative Analysis of the mechanical and environmental properties of soy-based PU and petroleum-based PU Table 4 Song PF., 2015, Trade names and suppliers of commercially-available soy polyols for the production of soybased polyurethane Table 5 Schmidt J., n.d., Nitrogen needs of soybean based on N Budget, Available at https://www.pioneer.com/ home/site/us/agronomy/library/nitrogen-fertilizer-for-soybean/#fig1 [Accessed 15 December 2015] Table 6 Cruse MJ, 2009, Organic sources of nutrient, Available at http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1692&context=etd [Accessed 15 December 2015] Table 7 UC IPM,2014, IPM approaches to pest management, Available at http://www.ipm.ucdavis.edu/GENERAL/ whatisipm.html [Accessed 10 December 2015] Table 8 Pimentel D., 2006, Energy inputs in a conventional soybean production system per hectare in the U.S, Available at http://www.organicvalley.coop/fileadmin/pdf/ENERGY_SSR.pdf [Accessed 10 December 2015] Table 9 Pimentel D., 2006, Energy inputs for a model organic soybean production system per hectare in the U.S., Available at http://www.organicvalley.coop/fileadmin/pdf/ENERGY_SSR.pdf [Accessed 15 December 2015] Table 10 Brookes G., Barfoot P., 2015, Additional crop production arising from positive yields effects of GM crops, Available at www.pgeconomics.co.uk/pdf/2015globalimpactstudyfinalMay2015.pdf [Accessed 15 December 2015]
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