Taking up valuable land and growing edible crops for biofuels poses a dilemma: Is it ethical to produce inefficient renewable energies at the expense of an already malnourished population? David Pimentel and colleagues from Cornell University highlight the problems linked to converting a variety of crops into biofuels. Not only are these renewable energies inefficient, they are also economically and environmentally costly and nowhere near as productive as projected.

In the context of global shortages of fossil energy – oil and natural gas in particular – governments worldwide are focusing on biofuels as renewable energy alternatives. In parallel, almost 60 percent of the world's population is malnourished increasing the need for grains and other basic foods. Growing crops, including corn, sugarcane and soybean, for fuel uses water and energy resources vital for the production of food for human consumption.

Professor Pimentel and his team review the availability and use of land, water and current energy resources globally, and then look at the situation in the US specifically. They also analyze biomass resources and show that there is insufficient US biomass for both ethanol and biodiesel production to make the US oil independent.

Their paper then looks at the efficiency and costs associated with converting a range of crops into energy and shows that in each case more energy is required for this process than they actually produce as fuel. The research finds a negative energy return of 46 percent for corn ethanol, 50 percent for switchgrass, 63 percent for soybean biodiesel and 58 percent for rapeseed. Even the most promising palm oil production results in a minus 8 percent net energy return. There are also a number of environmental problems linked to converting crops for biofuels, including water pollution from fertilizers and pesticides, global warming, soil erosion and air pollution. 

In the researchers' opinion, there is simply not enough land, water and energy to produce biofuels. They also argue that ironically, the US is becoming more oil-dependent, not less, as was intended through the production of biofuels. In most cases, more fossil energy is required to produce a unit of biofuel compared with the energy that it provides. As a result, the US is importing more oil and natural gas in order to make the biofuels.

The authors conclude that "Growing crops for biofuels not only ignores the need to reduce natural resource consumption, but exacerbates the problem of malnourishment worldwide by turning food grain into biofuels…Increased use of biofuels further damages the global environment and especially the world food system."

Article: Pimentel D et al (2009). Food versus biofuels: environmental and economic costs. 
Human Ecology DOI 10.1007/s10745-009-9215-8