WASHINGTON An analysis conducted by the Renewable Fuels Association and released today finds the net energy balance of corn-based ethanol at U.S. dry mill biorefineries averages 2.6–2.8, an improvement over previous estimates, reflecting efficiency gains. The figures build on USDA's recent findings of a 2.1–2.3 net energy balance.
RFA's own analysis uses more current dry mill energy use data than the recent USDA study, which explains why the RFA results are approximately one-third higher than USDA's findings. The net energy balance is a ratio of how much energy is required to produce the corn and ethanol, and then transport the fuel to end-users. In simple terms, a ratio of 2.8, for example, means every BTU of energy invested in the process to make and deliver ethanol results in 2.8 BTUs of available energy to the end-user.
In February, USDA issued its updated net energy balance report on corn-based ethanol, finding there has been a large improvement in energy balance since 1995, and a small but positive improvement since 2008. The previous USDA report, conducted in 2010, was based on 2008-era data and found that the balance was 1.9–2.3. RFA's analysis found that USDA used the same 2008-era dry mill energy use estimates for both its 2010 and 2016 reports.
According to RFA's own analysis, the energy balance of the top-performing quartile of biorefineries is in the range of 3.2–3.4, which approaches the USDA estimate of 4.0 for an ideally situated dry mill producing wet distillers grains.
"As this new analysis shows, the U.S. ethanol industry has made tremendous efficiency gains in recent years," said RFA President and CEO Bob Dinneen. "EPA should take note and update its lifecycle greenhouse gas modeling of corn-based ethanol under the renewable fuel standard to reflect these improvements. Today's ethanol plants are achieving the levels of efficiency that EPA assumed wouldn't occur until 2022."
The RFA analysis used dry mill energy use data from two other widely respected findings to support its results, Mueller & Kwik (2013) and Christianson & Associates (2016). To view a copy of the RFA analysis, visit here.