As governments around the world increasingly aware of the need to reduce dependence on fossil fuels, researchers continue to look for ways to create renewable energy, such as biofuels, which are energy sources from plants. There are a variety of biofuel types, with conventional or first generation biofuels being based on feed or food crops with high sugar or oil content. The most common forms of biofuels are ethanol, derived from plant fermentation, and biodiesel, derived from natural plant oil. Production of these fuels has been growing recently, reaching more than 100 billion liters in 2011, approximately 3% of total ground transport fuel globally. Biofuels have great potential as a clean and renewable energy source, but also run a great risk of destroying forest and other native ecosystems. Moreover, concerns about food security have emerged as areas devoted to food crop production are replaced with biofuel crops.
Ethanol is a type of alcohol that is obtained by fermenting sugar and starch components of plants materials using yeast. It can be derived from various vegetal sources – in North America, corn is the most popular source for ethanol, whereas in Brazil, sugar cane is common. Biofuel proponents estimate that one liter of sugar cane ethanol can reduce net CO2 emission by over 90%. Ethanol can replace gasoline or be blended to improve energy efficiency. The consumption of ethanol at a global scale is increasing by 10-20% per year. However, assessments of the feasibility and efficacy of first generation biofuels have been divided since governments began pushing for increased biofuel usage to meet emissions reduction goals.
Biodiesel is a type of vegetable oil produced from plant or animal feedstock with fatty acids. Common sources from tropical areas include soy and palm oil; biodiesel is widely used in Europe, which accounts for more than 80% of global biodiesel consumption. Biofuel proponents estimate that biodiesel can reduce net CO2 emissions by over 67.7% by replacing fossil fuels; additional benefits include reduction of harmful particulate matter and sulfates. However, biofuel use has led to massive levels of deforestation, especially with palm oil plantations in Southeast Asia. In Borneo / Kalimantan, a popular target of oil palm expansion, palm oil often replaces high carbon peat swamps, resulting in a significant global carbon loss compared to fossil fuels. Palm oil is also used for cooking oil and food processing in most of the developing world, as it yields more oil per land area than most other crops. Studies have found that about half of palm oil plantations established from 1990-2005 in Malaysia and Indonesia occurred in forests.
Global carbon balance: Worldwide, the carbon impact of biofuels development is difficult to estimate. Biofuels combustion releases less carbon than fossil fuels, but clearing land for cultivation of biofuels often results in a large overall release of carbon, when one quantifies the amount of carbon stored in the biomass of the cleared forest. In peatlands of Borneo, the total carbon value is even higher, as high levels of carbon are stored in the deep organic soil. Biofuel cultivation on degraded agricultural land, on the other hand, can result in net carbon savings (see analysis in Environmental Research Letters 2008), especially if they utilize perennial crops or mixed cropping systems, or waste or residue products. However, direct calculations are often complicated because biofuel cultivation may replace agricultural land and not forest land, creating a similar carbon value for that land unit, but may displace the agriculture into previous forest land, resulting in an overall net carbon loss. Other research from the EU reach similar conclusions that most biofuels are not green. The effects of indirect land use change on net greenhouse gas emissions has emerged as an issue that has reduced the widespread support for first generation biofuels. In Brazil, parts of the Amazon Basin forests are converted to soy production for biodiesel, while parts of the Cerrado dry forests are also being converted for sugarcane and soy production. In Indonesia and Malaysia, two countries that are the largest palm oil producers in the world, oil palm plantations have contributed to rapid deforestation of lowland tropical rainforests and peatlands. Land conversion involves the burning of existing biomass and soils, which leads to a significant release of CO2, thus contributes to a net increase in greenhouse gas emissions during the lifetime of biofuel production plantations.
Other concerns include the effects of biofuel production on food security and livelihoods, due to competing demands over land, especially in Southeast Asia and Latin America, where monoculture plantations have displaced local and indigenous communities. As such, the biofuels industry’s research focus as shifted to non-food crops that are less water- and land-intensive for biofuel production, as well as organic waste products. Advanced or second generation biofuels include wood based products, enzymes and yeast, algae, and cellulosic grasses such as switchgrass in North America. Sources include agricultural wastes (from rice, barley, wheat), forestry by-products such as saw dust or pulp, and herbaceous and woody plants, like switchgrass and alfalfa. Other biofuel sources like jatropha oilseed (Jatropha curcas), Indian beech (Pongamia pinnata) are being explored as options in South Asia. Jatropha oil in particular has gained much attention, and is now grown in the tropical and sub-tropical zone across Asia, Africa and Latin America to produce biodiesel. However, the social and environmental sustainability issues raised by oil palm and soy plantations are relevant to jatropha plantations as well, particularly in India, where the government has pushed for extensive land conversion to produce biofuels. Ultimately, the ability of such second generation biofuels to be more widely adopted depends on cost reductions for producing feedstock and improvements in technology, and whether or not net greenhouse gas emissions rates are reduced.
See more general information about biofuels and the environment at NatGeo, Energy Future Coalition and the New York Times, and read more about biofuels in different regions, or more about soy and palm oil specifically by following the links below.
Adler, P. R., Grosso, S. J. D., & Parton, W. J. (2007). Life-cycle assessment of net greenhouse-gas flux for bioenergy cropping systems.Ecological Applications, 17(3), 675-691.