Biofuels proponents are challenging the model that determines transportation fuel quality in the US at the Fuel Ethanol Workshop in Milwaukee.
"We should have included T70 as a metric in the model, it entirely changes the perception of the model," said Shon Van Hulzen, director of quality control at US ethanol producer POET, in a presentation Wednesday.
T70 is the temperature at which 70% of the fuel evaporates.
The Environmental Protection Agency uses the Motor Vehicle Emissions Simulator to determine the quality of transportation fuels. Individual states can then adopt the results of the model.
"The MOVES model is what state regulators use to determine fuel quality," said Dave VanderGriend, CEO of ICM.
But many biofuels industry groups and producers say that the model incorrectly attributes emissions to ethanol in gasoline.
Val Hulzen pointed to the T70 metric, which measures the volatility of ethanol.
"Using the T70 metric in the MOVES model, ethanol goes from raising emissions to lowering emissions," he said.
Geoff Cooper, senior vice president of the Renewable Fuels Association, said that the EPA's study used to build the new MOVES model looked at T50 and T90, but not T70.
"Ethanol burns cooler, so it would reduce that temperature," he said.
But the core of biofuels supporters' problem with the MOVES model lies in how the EPA's study attributed higher emissions to ethanol.
The EPA tested various transportation fuels and measured the emissions as they were burned. But Cooper said the quality of the gasoline was lower in the higher ethanol blends that were tested.
"As they tested higher ethanol blends in the EPAct study, they added more aromatics to the gasoline," he said.
Aromatics are compounds added to gasoline that biofuels supporters say are actually responsible for the higher emissions readings.
With the combination of ethanol seen as raising the volatility of fuel and increasing the emissions, biofuels proponents say the MOVES model incorrectly shows ethanol in a negative light.
Robert White, vice president of industry relations for the RFA, said the issues with the MOVES model are the largest hurdle in implementing higher ethanol blends.
Gasoline that contains up to 10% ethanol accounts for nearly all fuel sold in the US. Alternative blends such as E15, which contains 15% ethanol, are seen as the next step for growth in the biofuels industry.
"The EPA did not give the same volatility to E15 as E10," said White, pointing out that E15 cannot be sold during the summer when specifications are stricter. "Thirty percent of the country can't blend it and it's cost prohibitive for the other 70%," he added.
The updated MOVES model, MOVES2014, is due to be implemented in 2017.
"The EPA will see that increasing ethanol in gasoline increases emissions if we don't get fixed," Van Hulzen said in a call for industry participants to gather data to challenge the proposed model.
There is an effort to do a new study, funded by the biofuels industry, to remeasure emissions from fuels, he said.
"[The EPA] will see that increasing ethanol content in gasoline increases emissions if we don't get this fixed," Van Hulzen said.
