A recent study by the University of Minnesota that compares lifecycle emissions of gasoline, corn ethanol and cellulosic ethanol is faulty because it does not use realistic, comparable data sets, according to the National Corn Growers Association (NCGA). The report prematurely praises cellulosic ethanol as the best fuel alternative when it comes to reducing greenhouse-gas (GHG) and particulate-matter emissions despite the fact that it is years from production and use, while corn ethanol is available and being used today.
Another peer-reviewed study released in January by the University of Nebraska found much more positive news when it came to greenhouse gas emissions. Nebraska scientists analyzed the lifecycles of corn-ethanol systems accounting for the majority of U.S. capacity. They wanted to estimate GHG emissions and energy efficiencies on the basis of updated values for crop management and yields, biorefinery operation and coproduct utilization. The result: Direct-effect GHG emissions were estimated to be equivalent to a 48-59% reduction compared to gasoline, a twofold to threefold greater reduction than reported in previous studies.
“First and foremost, this Minnesota study is continuing the bad trend of comparing theoretical systems vs. real world systems,” says NCGA President Bob Dickey. “All assumptions made for the production and processing of biomass feedstocks for cellulosic ethanol have yet to be validated and executed economically.
“Secondly, while we have always seen great potential in cellulosic ethanol, we realize it is just that – potential,” Dickey says. “On the other hand, corn ethanol helps provide reduced GHG emissions compared to gasoline and is a good stepping stone to advanced biofuels and energy independence – as well as a stronger economy for America’s heartland.”
NCGA disagrees with the Minnesota report’s claims in the area of measuring land use change, stating that increased corn and ethanol production can be attained without increasing corn acres significantly, thanks to increased corn production per acre.
While it would only take 1.8 billion acres of field corn to produce 1 billion gallons of ethanol in the Corn Belt, the Minnesota study claims that using switchgrass to produce cellulosic ethanol would require the U.S. to convert more than twice that – 3.8 million acres of CRP – into switchgrass production to produce 1 billion gallons of ethanol.
NCGA also pointed out these flaws with the Minnesota study:
• The gasoline baseline assumptions were based upon domestic production of oil, which is a flawed assumption due to declining domestic production relative to total use.
• The study itself admits more economical ways of producing cellulosic ethanol must be discovered to realize the perceived gains. This admission nullifies any baseline data on cellulosics as presumptive.
• Valuation of carbon (C) by the authors are gross estimates at best. Current C offsets on the Chicago Climate Exchange (CCX) yield $2/ton of CO2 (or $7.33/ton of C in terms used by the Minnesota researchers). The paper’s estimates range from $88 to $162 – 22 times the going rate – before adding an ‘estimated $43/ton C’ as the social cost (which the authors admit can range from below $0 to over $300).
• Quantifying particulate-matter (PM) emissions is a moving target with new technologies reducing PM from all production systems through advanced scrubbing systems on stationary plants to new catalysts being installed to meet Tier 4 Diesel Standards.
”If people want the correct view of these issues, they should read the Nebraska report,” Dickey says, “and totally disregard the Minnesota report.”