Corn-based fuel cuts GHG emissions by 30% compared to petroleum — study

Source: Amanda Peterka, E&E reporter • Posted: Thursday, January 16, 2014

Corn ethanol has reduced greenhouse gas emissions by more than 30 percent compared to petroleum, according to a study backed by the ethanol industry and released today.

When compared to unconventional petroleum, the emissions savings from corn ethanol rise to 40 percent, the Life Cycle Associates study foundĀ .

In general, petroleum is becoming more carbon intensive while corn ethanol is contributing fewer greenhouse gas emissions, the report says.

“As the average carbon intensity of petroleum is gradually increasing, the carbon intensity of corn ethanol is declining,” the 47-page study says. “Corn ethanol producers are motivated by economics to reduce the energy inputs and improve product yields.”

Life Cycle Associates is a California-based company that analyzes fuel and energy systems. The company completed life-cycle greenhouse gas emissions assessments used in establishing the fuel pathways in California’s low-carbon fuel standard.

The firm’s new study was backed by the Renewable Fuels Association, an ethanol trade group. RFA’s chief economist, Geoff Cooper, served as project manager.

Life Cycle Associates used GREET, a model developed by researchers at Argonne National Laboratory, to estimate life-cycle greenhouse gas emissions.

The study found that, when compared to average petroleum, corn ethanol reduced greenhouse gas emissions by 32 percent in 2012. In 2022, corn ethanol is projected to reduce emissions by almost 43 percent compared to the base line.

Corn ethanol reduces greenhouse gas emissions by between 37 and 40 percent compared to unconventional oil produced by hydraulic fracturing and from oil sands, the study said.

“The majority of unconventional fuel sources emit significantly more GHG emissions than both biofuels and conventional fossil fuel sources,” the study said. “The biggest future impacts on the U.S. oil slate are expected to come from oil sands and fracking production.”

The analysis took into account indirect land-use change caused by increased corn ethanol production as well as advances in technology.

According to the study, corn ethanol emissions are decreasing because of increased energy efficiency and more opportunities for co-products, such as corn oil, in the ethanol production process. Recent studies by Purdue University and Argonne have also lowered estimates of land-use conversion associated with ethanol production.

A 2012 Argonne study concluded that corn ethanol can reduce life-cycle greenhouse gas emissions by between 19 and 48 percent.

The Renewable Fuels Association said new analysis signals that U.S. EPA’s methodology for measuring greenhouse gas emissions is flawed. The agency’s analysis — which was used to write the rule implementing the renewable fuel standard — assumes corn ethanol will reduce greenhouse gas emissions by 21 percent in 2022.

Ethanol’s contribution to greenhouse gas emissions remains a hotly contested subject, with environmentalists arguing that ethanol’s benefits are overstated. A Department of Energy-backed study last fall found that current life-cycle analyses, included EPA’s method, do not capture the full greenhouse gas impacts of ethanol (Greenwire, Sept. 26, 2013).