Nutrient and sediment pollution in streams and rivers could also both be attributed to soil erosion. High sedimentation rates carry financial consequences as they increase the cost of often-mandatory dredging for transportation and recreation. The committee observed that erosion might be minimized if future production of biofuels looks to perennial crops, like switchgrass, poplars or willows, or prairie polyculture, which could hold the soil and nutrients in place better than most row crops. The committee also identified other ways that farming could be improved, such as conservation tillage and leaving most or all of the cornstalks and cobs in the field after the grain has been harvested.
For biorefineries, the water consumed for the ethanol production process -- although modest compared with the water used growing biofuel crops -- could substantially affect local water supplies, the committee concluded. A biorefinery that produces 100 million gallons of ethanol a year would use the equivalent of the water supply for a town of about 5,000 people. Biorefineries could generate intense challenges for local water supplies, depending on where the facilities are located. However, use of water in biorefineries is declining as ethanol producers increasingly incorporate water recycling and develop new methods of converting feedstocks to fuels that increase energy yields while reducing water use, the committee noted.
|Contact: Jennifer Walsh|
The National Academies