Biofuels can be produced from many crops. At present, attention is focused on producing ethanol (alcohol) and biodiesel from a few food crops:
• Crops for ethanol production: corn (maize), sugar cane, sugar beet and wheat (plus, in the future, agricultural wastes, grass and wood for “cellulosic” or “lignocellulosic” ethanol).
• Crops for biodiesel production: rapeseed (canola), oilseed trees (Jatropha), soy, and oil palm.
Ethanol derived from biomass
Corn Based Ethanol: The current method of deriving ethanol from corn (maize) does not show promise 1. There is debate over the energy balance , with some studies showing positive and others negative energy balances. This is largely due to the way energy balance is calculated. Corn-derived ethanol booming in the U.S. and is being considered as a source of fuel in China. The agricultural practices used to grow corn in the U.S. are unsustainable, highly dependent on fertiliser, pesticides and much is GE corn. Some argue in the U.S. that corn derived ethanol is a useful transitional fuel to cellulose based ethanol, but ethanol production from corn will never meet the policy goals currently being promoted in the U.S.
Wheat (grain) based ethanol: Grain ethanol production plants are being planned in some European countries. There are concerns that grain-based ethanol could compete directly compete with food.
Sugar Cane Ethanol: The Brazilian ethanol program has received a tremendous amount of attention. Ethanol from sugar cane has a considerable positive energy balance and has resulted in a significant decrease in greenhouse gas (GHG) emissions in Brazil. However, there are currently considerable negative environmental and social impacts of growing sugar cane in Brazil 2, although it’s possible this could change in the future. If Brazil follows up on its plan to substantially increase ethanol production, existing concerns regarding agricultural practices and labour could increase. There is also concern that increased sugar cane production in Brazil could, directly or indirectly, push the agricultural frontier into the Cerrado, Amazon or Atlantic forests. Hence, sugar cane would have to be produced within the framework of sustainable agriculture avoiding social conflict and not entailing conversion of intact ecosystems to be acceptable to Greenpeace.
Sugar beet Ethanol: Sugar beet ethanol has not received the same amount of attention as sugar cane ethanol. However, in the EU, considerable agricultural surpluses of sugar beet exist and there are plans to use these to produce bio-butanol (similar to bio-ethanol) 3. There is considerable negative environmental impact of growing sugar beet in temperate European countries.
Biofuels from agricultural and forestry wastes
Cellulosic Ethanol: Cellulosic (or lignocellulosic) ethanol is ethanol derived from the cell walls of plants or woody material and can utilise grass, agricultural or forestry wastes. A recent survey confirmed that energy and GHG savings are the best for cellulosic ethanol, compared to ethanol derived from corn or sugar cane 4. A major effort is underway to produce cellulosic ethanol by second generation technologies which would be more efficient 5. In addition, ethanol derived from wastes does not have land-use implications associated it, as compared with ethanol produced from grain crops. In the future, crop wastes could become a major source of cellulose-based ethanol.
Gas and (non ethanol) liquid fuels: Production of synthetic gas from almost any type of wet biomass is growing. It uses the same type of process used to produce liquid and gaseous fuels from coal. The synthetic gas can be used directly as fuel, or almost any type of liquid fuel can be derived from it – most often biodiesel. This new generation of technologies shows promise and could prove to be part of the solution to climatic change. The likely near-term outcome is that cellulosic agricultural and forestry waste (wheat straw, corn stalks etc.) will be used.
Crops for Biodiesel
The debate on the extent to which biodiesel from crops can practically be used in transportation centres on conversion rates and the acreage necessary to substitute for gasoline products. It is possible that technology will develop to increase efficiency of biodiesel, but at present these are not efficient enough for large scale usage.
The projected large increase in the use of biodiesel could create problems regarding land-use. These land use concerns are particularly worrying where they concern global trade: with developed nations, such as the EU, aiming to import biodiesel from developing nations. They are worrying because the agricultural practices are largely unregulated at source.
Soy and Palm Oil: Soy in the Amazon and other parts of South America (e.g. Argentina) and palm oil in Asia Pacific are rapidly expanding. For example, soy in Brazil, Argentina and Paraguay and palm oil in Indonesia and Malaysia have become major drivers of deforestation 6 and, at least in Brazil , created modern-day slave labour and affected indigenous lands. Deforestation emits carbon previously stored in trees to the atmosphere, and therefore contributes to climatic change.
Soy expansion is currently driven by global demand for protein. However, in the future, global demand for biofuel may be a major driver for both palm oil and soy as well as for a number of other cash crops.
For both palm oil in Indonesia and soy in Brazil, round tables have been set up to discuss "sustainability" criteria for their expansion with the agro-industry. However, these are not strong enough and too vague to be an effective safeguard for biodiversity. Greenpeace does not participate in these round tables because our goal and position is to oppose any expansion of soy, palm oil and other cash crops into forests and other natural ecosystems as a key threat to terrestrial biodiversity. Soya or palm oil production that does not entail deforestation is likely to be feasible only on a small scale for local use.
Biodiesel from vegetable oil: With obvious limitations in scale, waste cooking or vegetable oil can be converted to biodiesel (by a simple chemical reaction that removes glycerine) and then used in regular diesel vehicle engines. All waste vegetable oil could be recycled to use as biodiesel. Besides, vegetable oil can be use directly (without chemical modification) in vehicle engines that have been modified, but these systems seem to be still experimental and less energetically efficient.
Energy costs and environmental effects of transportation of fuels: In general, the energy cost transportation of biofuels appears to be small in comparison to production costs. However, the transportation of cargo and trucks will have environmental impacts, as emissions of GHG from fuel combustion.
1. Shapouri, H., Duffield, J., Mcaloon, A.J. 2004. The 2001 Net Energy Balance of Corn-Ethanol. Proceedings of the Conference on Agriculture As a Producer and Consumer of Energy, Arlington, VA., June 24-25.
Farrell, A.E., Plevin, R.J., Turner, B.T., Jones, A.D., O’Hare, M., Kammen, D.M. 2006 Ethanol can contribute to energy and environmental goals. Science 311: 506-508.
Dias de Oliveira, M.E., Vaughan, B.E. & Rykiel, Jr. E.J. 2005. Ethanol as fuel: energy, carbon dioxide balances, and ecological footprint. Bioscience 55: 593-602.
2. Dias de Oliveira, M.E., Vaughan, B.E. & Rykiel, Jr. E.J. 2005. Ethanol as fuel: energy, carbon dioxide balances, and ecological footprint. Bioscience 55: 593-602.
4. Farrell, A.E., Plevin, R.J., Turner, B.T., Jones, A.D., O’Hare, M., Kammen, D.M. 2006 Ethanol can contribute to energy and environmental goals. Science 311: 506-508
5. Gray, K.A., Zhao, L. & Emptage, M. 2006. Bioethanol. Current Opinion in Chemical Biology 10: 141-146.
6. Pearce, F. 2005. Forests paying the price for bio-fuels. New Scientist 19th November 2005. Greenpeace 2006. Eating up the Amazon. http://www.greenpeace.org/international/press/reports/eating-up-the-amazon
7. Greenpeace 2006. Eating up the Amazon. http://www.greenpeace.org/international/press/reports/eating-up-the-amazon