Biodiversity and ecosystem services: Carbon-neutral corn ethanol produced using low-input high-diversity prairie biomass to power conversion facilities

Low-input high-diversity prairie grasslands grown on degraded soils can provide economically and environmentally valuable ecosystem services. They produce enough bioenergy to power the processing of corn into ethanol and sequester enough carbon to turn corn ethanol into a carbon neutral biofuel. Total lifecycle greenhouse gas emissions of conventionally-produced corn ethanol are only 12% lower than for gasoline, resulting in a net release of 2400 kg of carbon-dioxide-equivalent greenhouse gases per acre of corn used in ethanol production. Of this amount, approximately half is released by burning natural gas or coal, including coal used for electric generation, to power the conversion of corn into ethanol. Replacing the fossil energy used at ethanol production facilities for milling, fermentation, and distillation with biomass harvested from highly diverse prairies grown with low agrichemical inputs not only increases the return on the fossil fuel energy invested from 25% to 190% but also offsets enough carbon dioxide release to generate a carbon neutral biofuel. The biomass produced and carbon sequestered on about 3/4 acre of restored prairie can power the processing and carbon neutralization of ethanol from an acre of corn and may lower the energy operating costs for the faculty. Utilizing prairie biomass in such a manner could greatly increase the environmental and economic value of the ethanol produced while also fostering the restoration of native grasslands, which are the most endangered ecosystem in this country, thereby providing agrichemical mitigation, wildlife habitat, decreased soil erosion, and other benefits.