Net energy yield (NEY) and greenhouse gas (GHG) emissions reduction compared to gasoline from different types of corn-ethanol systems used as default scenarios in the BESS model. NEY includes ethanol plus coproduct energy credit minus energy inputs. A closed-loop biorefinery with anaerobic digestion (CL) reduced GHG emissions by 67%. Credit: Yale Univ.
Direct-effect GHG emissions from corn ethanol are equivalent to a 48% to 59% reduction compared to gasoline—a twofold to threefold greater reduction than reported in previous studies—as a result of recent improvements in efficiency throughout the production process, according to a study by researchers at the University of Nebraska-Lincoln (UNL).
The team of UNL researchers evaluated dry-mill ethanol plants that use natural gas. Such plants account for nearly 90% of current production capacity. An open-access paper on the study was published 21 January in the Journal of Industrial Ecology.
The direct-effect emissions assessment considered the energy used for feedstock production and harvesting (e.g., fossil fuels for field operations and electricity for grain drying and irrigation) as well as upstream costs for the production of fertilizer, pesticides, and seed; depreciable cost of manufacturing farm machinery; and the energy required in the production of fossil fuels and electricity.
Detailed report : Here
Regional variability in corn-ethanol system performance due to differences in inputs to and outputs from crop production: (A) Net energy yield of the corn-ethanol production life cycle, given a new natural gas biorefinery. (B) Greenhouse gas intensity of corn production (kg CO2e Mg-1 grain), and life cycle GHG reductions of corn-ethanol compared to gasoline (%), given a new natural gas biorefinery. Results were calculated with the BESS model. Credit: Yale Univ.
