Corn ethanol revisited

This post originally appeared on TriplePundit and is part of a series on biofuel sponsored by Novozymes.

There are a number of reasons why corn ethanol is looked upon with skepticism if not outright scorn in this country, particularly outside of the Midwest. The fact that corn became a leading source of biofuel feedstock as the result of a large and powerful lobbying effort draws suspicion from the left. The fact that its move into prominence was founded on large government subsidies and mandates draws criticism from the right. And its inherent marriage to large-scale industrial agriculture and the fact that it potentially diverts capital resources away from other renewables is not at all popular with the environmental community. There are also many people across the political spectrum who are concerned about the question of agricultural resources (e.g. land, water, fertilizer) being diverted away from food production, especially at a time of massive droughts and when so many people in the world are going hungry.

These are all true statements, though not necessarily defining ones. They do not tell the whole story. Indeed, there are a number of facts about corn ethanol that are not widely known which could change people’s perceptions.

Untrue, for example, are assertions that corn ethanol is a net energy loser, or that it provides little or no benefit from a climate change perspective. I spoke to Bob Dinneen, President of the Renewable Fuels Association, last week, and he said, “Those who say it’s a net negative are looking at reports from 25 years ago.” Indeed some of the earlier studies did show a negative balance. But much has changed in recent years, and not just in life cycle analysis methodology.

Because of the investments in productivity and modernization that have been made possible as the result of government support, yields have increased both in terms of bushels per acre, and also in gallons per bushel. Dineen says, “Ethanol extraction has increased from 2.2 to 2.8 gallons per bushel, while corn yields have increased from 80 to 160 bushels per acre in one generation.” This has resulted in an energy balance that, according to the USDA, is now 2.3 Btu out for every Btu used for production or a net Energy Return on Energy Invested (EROEI) of 1.3. In cases where biomass is being used to power the mills, that ratio can be as high as 1.8.

Furthermore, because of improved agricultural technology, nitrogen use has decreased by 20 percent since the mid-90s and direct energy use has fallen by 50 percent. Greenhouse gas emissions are 18-22 percent lower than gasoline. The cost of production of ethanol in the U.S. is now so low that we have actually begun exporting ethanol to Brazil, long considered the world’s ethanol leader.

To put this in perspective, consider the fact that the EROEI for gasoline is only 0.84, which is 35 percent lessthan ethanol. Of course we’d like the EROEI to be higher, especially when we consider the indirect energy expenditures such as building roads and other infrastructure and the carbon emitted when natural land is converted to farmland. On the other hand, the EROEI for cellulosic ethanol is 10, a fact that we will be coming back to later in this series.