Ecological dimensions of biofuels: state of the science
Are biofuels a renewable, environmentally friendly energy source? The Ecological Society of America reviews bioethanol and biodiesel in conventional production as well as feedstocks still in development. Biofuels in commercial scale production are made from the sugars and oils of food crops, and share the ecological impacts of high intensity agriculture. Corn, the primary biofuel source in the United States, demands a lot of fuel to produce fuel. It needs nitrogen fertilizer, fixed using energy-intensive industrial processes. Much of that nitrogen ends up in waterways, where it causes problems for fish and fisheries. In some of the drier western states, farmers are drawing down groundwater resources to irrigate corn for biofuel. Cornfields are usually tilled, which releases greenhouse gasses stored in soil, loses topsoil to erosion, and loses water to evaporation. Much hope has been placed in the "cellulosic" biofuels for their superior environmental benefits. Made from grasses, woody crops like poplar, crop silage and other plant wastes, cellulosic ethanol does not compete with the food supply for feedstocks, which consume fewer resources, and are potentially more compatible with wildlife. Mixes of perennial native grasses, for example, offer better habitat than monocultures and don't need intensive fertilizer, pesticide, and water inputs. But cellulosic ethanol contributes only 0.5% of current biofuel production, and still faces major implementation challenges to become commercially viable. Algal biofuels remain in development. The authors conclude the report with recommendations to get the most out of biofuels going forward, improving ecosystem services, reducing greenhouse gases, and providing new income for rural communities.
|Contact: Liza Lester|
Ecological Society of America