The growth in U.S. fuel ethanol production - at the highest level ever in 2014 at 14.3 billion gallons - also has outpaced growth in corn consumed as feedstock, the U.S. Energy Information Administration said this week. And as the industry has grown, it has become more efficient, using fewer bushels of corn to produce a gallon of ethanol.
To compare, EIA said if ethanol plant yields per bushel of corn in 2014 had remained at 1997 levels – when ethanol made up just 1% of the total U.S. motor gasoline supply – the ethanol industry would have needed to grind an additional 343 million bushels, or 7% more corn, to produce the same volume of fuel.
To supply this incremental quantity of corn without withdrawing bushels from other uses would have required 2.2 million additional acres of corn to be cultivated, EIA said.
That's an area roughly equivalent to half the land area of New Jersey.
Why ethanol yield has increased
Several factors contributed to the yield increases from a bushel of corn, EIA said. Larger scale operations have allowed producers to incorporate better process technology, like finer grinding of corn to increase starch conversion.
Other changes include improved temperature control of fermentation, which optimizes yeast productivity.
The growth of the corn ethanol industry also enabled the development of better enzymes and yeast strains for improved output per bushel of corn, EIA said.
This growth in ethanol production has been made possible by a rise in demand for ethanol to increase octane levels as methyl tert-butyl ether, a gasoline additive, has been phased out of gasoline.
Growth also is in part because of Renewable Fuel Standard targets, enacted in 2005 and expanded by subsequent legislation in 2007, which "effectively placed a floor under ethanol demand," EIA said.
Recently, ethanol's volumetric share of total U.S. motor gasoline supply has been just below 10%, reaching 9.8% in 2014.
Continued reading: 2014 U.S. ethanol export volumes highest in three years
Source: U.S. Energy Information Administration