Biofuels: The Environmental Downside

Published in:  American Bar Association, ABA Agricultural Management Committee Newsletter, Fall 2009


Guy R. Knudsen

Biofuels are obtained from living or recently living biological materials, typically plants and plant-derived products, in contrast to fossil fuels (coal, oil, natural gas) which were formed from plants and animals living up to 300 million years ago.  Biofuels include ethanol and biodiesel, and are widely considered to be promising sources of renewable energy.  Ethanol as a biofuel can be produced from a variety of crops including corn, sorghum, wheat, sugar cane, and fast-growing trees such as poplar.  Ethanol typically is combined with gasoline, promoting more complete fuel burning and reducing certain harmful emissions including carbon monoxide and hydrocarbons.  Biodiesel is derived from natural oils of plants including soybean, palm, and rapeseed, hemp, algae, etc., and also from waste vegetable oil and animal fat. 

Because plant-derived biofuels represent a renewable resource, and since plants themselves remove CO2 from the atmosphere, biofuels have been hailed as an effective and sustainable source of energy, with environmental benefits including mitigation of climate change.  Backed by growers, politicians, and many environmentalists, subsidized biofuel production and use in the U.S. and Europe have expanded rapidly in recent years.  In the U.S., the 2007 Energy Act mandated significantly increased usage of cellulosic ethanol.  The 2008 Farm Bill provides subsidies for growers of biofuels crops as well as for refiners who convert them to ethanol.  Corn-based ethanol is currently the most widely used biofuel in the United States.  In Europe, the EU several years ago set a target whereby biofuels such as rapeseed, palm oil and bio-ethanol were to account for 10% of transport fuel by the year 2020 (although that target has recently been lowered to 6%.)

However, an increasing number of scientists and economists are warning that problems associated with biofuels continue to be ignored by policy-makers.  One concern relates to “carbon-neutrality” and the actual energy yield of biofuels. Carbon-neutrality is based on the idea that CO2 released from combustion of biofuels is cancelled out by CO2 absorbed by the growing plants.  However, if the CO2 released during crop production and biofuel processing is also factored into the equation, by some estimates many biofuels come up short.  There are similar concerns about the true amount of net energy provided by different biofuels, with some (albeit controversial) studies indicating that for many crops, more fossil energy is required for biofuel production than is actually produced as fuel (e.g., Pimentel et al., Human Ecology 37:1-12.) 

A second major concern relates to the diversion of cropland from food production to biofuel production.  When biofuel crops replace food crops, there may be an accompanying rise in food prices.  When croplands are shifted to biofuel production in developing countries particularly, economic and social inequities may result. 

The third area of concern about biofuel production, which will be the focus of the remainder of this article, is the often ignored or underestimated potential for environmental damage.  There are several general areas of environmental concern related to biofuel production, including adverse effects on air pollution and global warming, deforestation and loss of habitat diversity, and production-associated problems involving water usage, fertilizers, and pesticides. 

Adverse effects on air pollution and global warming

At first glance, the production of biofuel crops, which actually remove CO2 from the atmosphere, would appear to be environmentally benign.  However, these crops have to grow somewhere, and in much of the world the conversion to biofuel crops involves removal (including burning) of the original tropical forest, peatland, or other vegetation.  For example, there has been a major effort to plant and harvest oil palms in several tropical developing countries, including Indonesia, Malaysia, Thailand, and some West African countries.  Production has approximately doubled in the last twenty years.  The rapid release of CO2 into the atmosphere that accompanies land clearing, as a result of biomass burning and decomposition of plant material and soil humus, potentially negates any greenhouse gas benefits of subsequent biofuels crops, perhaps for many years to come. 

Biofuel crops may contribute to atmospheric pollution in another way: production of both corn and rapeseed (the most widely planted biofuel crops in the U.S. and Europe, respectively) requires large inputs of nitrogen fertilizer.  This can result in significantly higher release of nitrous oxide, a potent greenhouse gas, into the atmosphere.  A recent study (Crutzen 2007,  Atmos. Chem. Phys. Discuss. 7:11191–11205) estimated that biodiesel produced from rapeseed can result in up to 70% higher greenhouse gas emissions compared to fossil fuels, while corn can result in up to 50% higher emissions.  To summarize, growing and burning many biofuels may actually raise rather than lower greenhouse gas emissions.

Deforestation and loss of habitat diversity

Habitat loss due to the increasing conversion of wildlands to biofuel croplands will have lasting and deleterious effects on biological diversity, i.e., the numbers and distribution of species of plants, animals, and microorganisms in a given area.  For example, oil-palm plantations cover over 13 million ha, primarily in Southeast Asia, where they have replaced the biologically-rich tropical rainforest (Finn et al. 2009.  Conserv. Biol. 23:348-358).  It was found that trees, lianas, epiphytic orchids, and indigenous palms were completely absent from oil-palm plantations, and that the majority of remaining plant and animal species in those plantations were of low conservation concern.  The situation is similar with soya, used as a raw material for biodiesel, and production of which in large plantations is a major factor behind the destruction of the Amazon rainforests.  Conversion of forested lands to short-rotation biofuel cropping systems has the potential for release of carbon stored as soil organic material, along with increased erosion and reduced soil fertility. 

Another negative consequence of increased biofuel production in ecologically sensitive areas is the potential increase in numbers of invasive species.  As efforts continue towards identifying new biofuel crops, including non-native species, it is important to realize that a number of plant traits considered to be ideal for a biomass crop (e.g., high biomass production per unit energy input, efficient use of light, water and nutrients, perennial growth) are also common features of invasive plant species.  As an example of a poorly-planned crop introduction, the plant known as Johnson grass was introduced as a forage grass and has now become an invasive weed in many states.  Some of the same concerns about invasiveness arise around cellulosic agrofuels based on fast-growing genetically engineered trees.

Despite the economic attractiveness of many of these new biofuel crops, and their purported benefits related to global climate change, the possible ecological risks associated with them need to be carefully assessed prior to their introduction.  Indeed, programs aimed at reducing deforestation may well provide a more effective climate-change mitigation strategy than conversion of forests for biofuel production, and would have the additional benefit of helping countries to meet their international commitments for biodiversity support (Finn et al 2009).  Arguably, appropriate management practices will help to reduce potential deleterious environmental impacts of biofuel production.  On the positive side, there is the possibility that if biofuels are produced so as to reduce rather than increase atmospheric greenhouse gases, a beneficial impact on biodiversity might be attained (Sala et al.  2009. SCOPE International Biofuels Project). 

Problems with biofuel corn

Corn-based ethanol is the most widely used biofuel in the United States; e.g., in 2006 approximately 18% of the U.S. corn harvest was directed towards grain ethanol production. Unfortunately, corn ethanol may also be the most environmentally damaging of all the crop-based energy sources.  The economic and political clout behind taxe breaks for corn ethanol and subsidies for building ethanol plants in the U.S. are enormous, but critics suggest that as a strategy to reduce greenhouse gas emissions, corn ethanol falls far short of the claims made by its proponents.

Corn is a relatively inefficient biofuel crop, in part because of the extensive inputs needed to grow it.  The National Agricultural Statistics Service (NASS) estimated that the 2005 corn crop consumed 157 million lbs of herbicides and 4.8 million lbs of insecticides.  Continuous corn production (“corn-on-corn”), in particular, is a highly unsustainable agronomic system. A typical corn-soy rotation with soil-conserving no-till production of nitrogen-fixing soybeans is less potentially damaging to surrounding ecosystems. Corn typically uses more fertilizer than any other crop in the U.S.  Nitrate leaching, resulting from high levels of nitrogen fertilizer application, is the main contributing factor to nitrogen pollution of groundwater and surface and coastal waters.  Also, via the process of denitrification, nitrates in soil are converted to the greenhouse gas nitrous oxide.  Corn production results in significant soil erosion, causing a loss of soil fertility and impairing the quality of aquatic life and drinking water.  Increased algal outbreaks and fish kills have been attributed to high fertilizer usage, including that associated with increasing corn acreage. The so-called ‘dead zone’ in the Gulf of Mexico, where fertilizer runoff from Midwestern farms drains via the Mississippi river system, could worsen under corn-on-corn production that serves biofuels.

Are governments stepping back from biofuels?

In recent years, a number of national and local governments have quietly scaled back their previously enthusiasm towards the promotion and subsidy of biofuels.  In Europe, several governments are rolling back their previous across-the-board biofuel subsidies, perhaps in tacit acknowledgment that the environmental and economic benefits have often been overstated.  For example, the Netherlands recently decided to no longer subsidize the importation of palm oil, a major source of ‘green’ electricity generation, after it was realized that the supplying Asian plantations were largely being created from drained peatlands, with severe environmental consequences.  Nations including Britain, France, Germany, the Netherlands, Switzerland, Australia, and Canada have reduced or revised incentives for biofuel growers and/or refiners.  In many instances, the new guidelines will require that manufacturers and sellers quantify the net environmental effects of a biofuel, before becoming eligible for subsidies.

Closer to home, the city of Berkeley, California, is now reconsidering its six-year policy of using biodiesel in city trucks and machinery.  In the wake of a new study claiming that biodiesel production and use actually may increase greenhouse gases worldwide, as well as exacerbating world hunger, Berkeley has stopped receiving shipments of soybean-derived biodiesel pending further analysis of the city’s Community Environmental Advisory Commission report and recommendation.  The decision did not sit well with the National Biodiesel Board, a trade association representing the biodiesel industry, which claimed that the decision was based on “misunderstandings about how soybeans are farmed” (See, e.g, Kimball Nill, US Soy is More Sustainable than Ever, Agricultural Management Newsletter CITE).  Increasingly, depending upon where and how these crops are grown, however, the scientific literature has been less than sanguine about the future of biofuels; for example, a recent Swiss study which concluded that environmental costs of fuels made from U.S. corn, Brazilian soy, and Malaysian palm oil may be greater overall than those of the fossil fuels they would replace (Scharlemann and Laurance, Science 319:52-53). 

Where do we go from here?

As society attempts to transition from fossil fuels to renewable energy sources, it is likely that biofuels are here to stay, along with solar, hydro, and geothermal power.  Truly sustainable biofuel production may yet play a valuable role in mitigating global climate change and improving environmental quality.  But in order to do so, it will be necessary for policy to be based on sound science rather than shortsighted economic considerations.  Some crops will never be environmentally and economically viable biofuel candidates, despite intense political efforts to make them so.  In a recent published policy statement the Ecological Society of America summed up the need as follows:  “Biofuels have great potential, but the ecological impacts of their development and use must be examined and addressed if they are to become a sustainable energy source.  The sustainability of alternative biofuel production systems must be assessed now, in order to maximize the potential for developing truly sustainable scenarios – that is, profitable systems that can provide adequate biomass with the least amount of environmental damage.” (,

Guy R. Knudsen is Professor of Microbial Ecology & Plant Pathology at the University of Idaho, and a private practice attorney in environmental law.  You may contact him via e-mail at


About Guy Knudsen

Guy R. Knudsen,
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