The EPA is requesting comment on its lifecycle analysis (LCA) of greenhouse gas (GHG) emissions associated with using barley as a feedstock to produce ethanol.  According to the Agency, depending on the production processes, ethanol made from barley can meet two threshold requirements needed to qualify as a renewable fuel under the federal renewable fuel standard (RFS) program.

The Agency says it will consider all relevant comments on the LCA before taking final action that could lead to an amendment admitting the barley ethanol pathway into the RFS program. 

The Agency considered a number of factors to project that as much as 140 million gallons of ethanol can be manufactured from barley by 2022.  That amount of ethanol would require about 3.11 billion pounds of barley as a feedstock.

Estimating GHGs

Assessments of lifecycle GHG emissions are conducted under the RFS program to determine which fuel pathways meet the GHG reduction thresholds for the four renewable fuel categories specified in the Energy Independence and Security Act of 2007 (EISA).  EISA requires a 20 percent reduction in lifecycle GHG emissions for renewable fuel produced at new facilities (those constructed after EISA enactment), a 50 percent reduction for biomass-based diesel or advanced biofuel, and a 60 percent reduction for cellulosic biofuel. 

For the original March 2010 RFS rule, the Agency conducted LCAs for pathways that would produce the largest amount of ethanol.  Since then, the EPA has looked at other pathways that would produce lesser amounts of renewable fuel.  A “pathway” is defined as a renewable fuel feedstock, fuel type, and production process. 

In conducting LCAs under the RFS, the EPA uses models that account for energy and emissions inputs for fuel and feedstock production, distribution, and use as well as economic models that predict changes in agricultural markets.  The Agency says it used the same approach to estimate global land use change and GHG emissions from using barley as a feedstock as it used to analyze other biofuel pathways. 

Natural gas

EPA’s draft analysis indicates that ethanol produced from barley has an estimated lifecycle GHG emissions reduction of 47 percent compared to baseline conventional fuel when the ethanol is produced at a dry mill facility that uses natural gas for all process energy, uses electricity from the grid, and dries up to 100 percent of distillers grains.  Such barley ethanol would therefore meet the minimum 20 percent GHG emissions reduction threshold for conventional biofuels under the RFS program.

In addition, the EPA analyzed two potential options for producing barley ethanol that would meet the 50 percent GHG emissions reduction threshold for advanced biofuels. 

First, the higher threshold would be met if the ethanol is produced at a facility that uses no more than 30,700 Btu of natural gas for process energy; no more than 4,200 Btu of biomass from barley hulls or biogas from landfills, waste treatment plants, barley hull digesters, or waste digesters for process energy; and no more than 0.84 kWh of electricity from the grid for all electricity used at the renewable fuel production facility, calculated on a per gallon basis. 

Second, ethanol produced from dry-milling barley can also meet the advanced biofuel GHG reduction threshold if the production facility uses no more than 36,800 Btu of natural gas for process energy and also uses natural gas for on-site production of all electricity used at the facility other than up to 0.19 kWh of electricity from the grid, calculated on a per gallon basis.

Click here for EPA’s notice requesting comment on the GHG LCA for the barley ethanol pathway.