Blog Post

Producing Ethanol From Corn Is a Bad Idea

Producing ethanol from corn is a bad idea not only because of the poor energy return on investment (EROI), but also because of the impact it is having on ecosystems in the Midwest

Production of ethanol has dramatically increased acreage devoted to corn in the Midwest.Photo Credit: Lynn Betts, USDA-NRCS

Corn-based ethanol as a vehicle fuel has never been a good idea. But an in-depth investigation by Dina Cappiello and Matt Apuzzo of The Associated Press, published last week, outlines a lot of other reasons why we should finally kill this particular farm subsidy.

Where did we get this idea to begin with? The U.S. is one of the most agriculturally rich nations in the world, and we’re also one of the world’s largest fossil fuel importers. It makes sense on some levels to convert some motor fuel to biobased sources, such as ethanol and biodiesel—because we can produce it ourselves, helping to wean our dependence on oil from the Middle East and other politically unstable or unfriendly places.

Also, in theory, biofuels should help to reduce greenhouse gas emissions, since the raw materials (corn in the case of ethanol) is produced, in part, using solar energy via photosynthesis. The Obama Administration, like the Bush Administration before it, has touted ethanol as a strategy for reducing our nation’s greenhouse gas emissions.

Energy return on investment

I’ve written here in the past about the energy return on investment (EROI) with ethanol. Depending on whose study you believe it either takes a little more or a little less energy to produce corn-based ethanol than that end-product contains. That EROI ratio ranges from 0.8:1 to 1.5:1, depending on the study.


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Any time the EROI is less than 1:1, it takes more energy to produce the fuel than the fuel contains. Even giving the ethanol industry the benefit of the doubt by assuming the actual EROI is 1.5:1, that means to produce a gallon of the fuel takes two-thirds of a gallon (equivalent) of fuel—diesel for tractors and combines on the farm, natural gas to produce nitrogen fertilizer, natural gas and electricity at the ethanol plant, and energy to ship that fuel around the country.

By comparison, the ethanol produced from sugar cane in Brazil has an EROI closer to 8:1—for every gallon (equivalent) invested you get about eight gallons back out.

No matter whose numbers you believe, from an energy standpoint turning corn into ethanol to fuel our cars makes little sense.

Corn production is energy-intensive and results in significant nutrient pollution.Photo Credit: USDA-NRCS

Land conversion to corn production

Even more troubling than the dubious energy balance of ethanol is the land conversions that have occurred as demand for corn has increased in recent years. Just since 2008, according to the AP investigation, more than 5 million acres of land that had been set aside as part of the Conservation Reserve Program have been converted to corn production—an area greater than Yellowstone, Yosemite, and The Everglades National Parks combined.

Since 2006, some 1.2 million acres in Nebraska and the Dakotas that had never been tilled have been converted to corn and soybean production. This is even worse than converting conservation acreage into tilled farmland—since much of the conservation land had once been tilled. When virgin prairie is converted to farmland, along with losing the biodiversity on that land, a significant amount of carbon that was stored as organic matter in the soil is released into the atmosphere—contributing to greenhouse gas emissions.

Increased fertilizer use

The dramatic increase in corn production in recent years has also dramatically increased fertilizer use. Between 2005 and 2010, according to the AP investigation, nitrogen fertilizer use increased by 1 billion pounds, with another billion-pound increase likely having occurred since 2010.

Along with requiring a lot of natural gas to produce all that fertilizer, the runoff from that farmland is a huge pollution problem and contributes directly to the “dead zone” that occurs each year in the Gulf of Mexico.

If you've read our report on biobased materials in building products (see Biobased Materials: Not Always Greener), none of this should come as a great surprise. Behind seemingly good environmental ideas often lie complexities and negative impacts.

Corn for energy vs. food

As demand for corn increased to meet increasing mandates for ethanol in U.S. gasoline, the price of corn increased (commodity pricing is driven by supply and demand). In our increasingly global markets this affected food prices in developing countries that rely heavily on corn. Corn prices climbed to $7 per bushel in the U.S., double what they had been a few years earlier, and this dramatically increased food prices in Mexico, leading in some places to food riots.

Prices of corn have since dropped somewhat and record harvests are expected this year, but prices are still above where they were ten years ago.

Reevaluating our ethanol policy

The AP report came out just as the Obama Administration is reconsidering the ethanol mandates that have fueled the dramatic increase in corn production. The U.S. Environmental Protection Agency has proposed scaling back on the biofuel mandates in the Renewable Fuel Standard. Legislation passed in 2007 called for increasing the production of biofuels each year, with production reaching 16.55 billion gallons this year (2013) and rising to 36 billion gallons by 2022.

Corn harvest in Iowa.Photo Credit: Tim McCabe, USDA-NRCS

But when that legislation was passed, the consumption of gasoline was expected to continue rising, so the quota could have been achieved without increasing the percentage of ethanol in gasoline beyond the 10% that car makers are comfortable with. More ethanol in gasoline can cause corrosion in engines. With cars and light trucks becoming more fuel efficient, the numbers weren’t working.

EPA has proposed scaling back the ethanol mandate in 2014 to 15.21 billion gallons, down 14% from where it would be under the Renewable Fuel Standard—and just under 10% of the motor fuel sold in the country. An unusual coalition of oil companies and environmentalists is proposing going further and eliminating the biofuel mandates altogether.

The road ahead

I, like many others, have been hoping that “cellulostic ethanol” (made from agricultural residue like corn stalks rather than high-value corn) would advance more quickly than it has. So, along with proposing a reduction in the overall biofuel mandate, EPA last week proposed cutting the target for so-called “advanced biofuels” from 2.75 billion gallons this year to 2.2 billion gallons next year.

In the coming weeks, during the 50-day comment period for the new EPA rules, expect to see a barrage of dueling television ads on this issue.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.

Published November 18, 2013

(2013, November 18). Producing Ethanol From Corn Is a Bad Idea. Retrieved from

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November 25, 2013 - 1:09 pm

One thing which is not immediately obvious to many people is that, even with the most generous assumptions that corn ethanol's EROEI us 1.5, it's still a losing deal - and this is true even if you ignore the (enormous) environmental costs of growing this much corn.

This article helps explain this particular issue:

By graphing the net surplus energy (i.e. the energy available to do everything in civilization OTHER than harvest more energy) as a function of EROEI, we can see that a ratio of better than 1:1 is not by itself sufficient.  The ratio needs to be substantially positive, otherwise your civilziation spends all its time in a desperate quest for the next tidbit of energy - at which point it them immediately plows almost all of it back into production.

The author of the linked article draws a line at an EROEI of 8, and calls that the threshold of viability for a technological civilization.  You can argue about where that threshold actually lies, but I think it's beyond argument that such a threshold exists, and is substantially greater than 2:1.  And it's probably located in roughly the range the author indicates, somewhere between 5:1 and 10:1.