Preface. In this post the New York Times writes about renewable airplane fuel from corn ethanol, and questions whether there is enough water and a few other problems. First I’m going to summarize their issues with this, and then follow with some of what I’ve written about ethanol at my website www.energyskeptic.com and in my books Life After Fossil Fuels: A Reality Check on Alternative Energy; and When Trucks Stop Running: Energy and the Future of Transportation”
Bearak M et al (2023) Airlines Race Toward a Future of Powering Their Jets With Corn. Carriers want to replace jet fuel with ethanol to fight global warming. That would require lots of corn, and lots of water. New York Times.
Here is a summary of the New York times article.
Today, 100 million acres have corn. Powering airplanes would require doubling ethanol production, which already consumes 40% of corn production. But:
- It can take hundreds of gallons to produce a single gallon of ethanol (Hoekman 2017)
- One of the reasons that lobbyists and farmers are trying hard to make this happen is to get an extension of the Sustainable Aviation Fuel credit of $1.25 per gallon of ethanol, which expires after 2024 (IRS 2022)
- Groundwater is disappearing rapidly and alarmingly (Rojanasakul 2023).
- Climate change is causing droughts, heatwaves, and making rainfall less predictable, which puts even more pressures on America’s vanishing aquifers
- So just as mining and extracting fossil fuels have environmental costs, so does growing even more corn to make ethanol
- From 1964 to 2017 irrigation for corn grew by 500%
- Ethanol already consumes an astounding 40% of the corn crop
- It takes fossil fuel energy to plant, fertilize, water, harvest, transport and distill corn into ethanol
- Soil conservation may suffer if farmers only grow corn instead of rotating it with soybeans and other crips, or use conservation land to grow corn (which would pay more money than the government is currently paying them NOT to grow corn on this fragile land)
But the article left out many issues. What follows is from my website www.energyskeptic.com, and my books Life After Fossil Fuels: A Reality Check on Alternative Energy; When Trucks Stop Running: Energy and the Future of Transportation. There is so much to be said that if you want to learn more, Life After Fossil fuels has a lot of material I don’t have room to put in this post.
Much of the food and corn grown in the U.S. is over the Ogallala aquifer, which is vanishing and won’t be recharged until after the next ice age. A better choice would be cellulosic ethanol since grasses don’t need irrigation. But cellulosic ethanol isn’t commercial and may never be.
Although the article did mention that it takes fossil fuels to produce corn and ethanol, it left out that more fossil fuel energy is used to create ethanol than is contained in the ethanol! This is known as a negative net energy return, since it the energy returned on energy invested (EROEI) is less.
Several scientists who have studied energy return ratios have estimated our civilization needs an EROI of at least 11 (Murphy 2014) or even higher, perhaps 12–14 (Lambert et al. 2014). Mearns (2008) calculated that when the net energy provided to society has an EROI of nine or less, the energy returned declines so exponentially it is like going off a cliff.
There have been dozens of studies of the EROI of corn ethanol. The best peer-reviewed research falls between a range of slightly positive to negative −0.82. At best an EROI of 1.3, far below the EROI needed to sustain civilization (Giampietro et al. 1997; Pimentel and Patzek 2005; Murphy et al. 2011).
It takes some 680 gallons of water per liter of ethanol (Gerbens-Leenes et al. 2009), and for every gallon of ethanol produced, 12 gallons of noxious sewage effluent are released that need to be treated (Schulz 2007).
Corn also uses more nitrogen fertilizer (made out of and with fossil fuel natural gas) than most crops (Padgitt et al. 2000; Pimentel 2003; NRC 2003), and significant amounts of phosphorus.
In summary, corn (and soy) erode more topsoil, cause more pollution, global warming, acidification, eutrophication of water, use more fossil fuel fertilizer and pesticides, water treatment costs, fish kills, and biodiversity loss than most other crops (Powers 2005; Troeh and Thompson 2005; Zattara and Aizen 2019). The energy return would be even more negative if the energy to remediate these issues were included.
One reason climate was supposed to be the why. The Renewable Fuel Standard (RFS) of 2007 mandated that only biofuels which lowered greenhouse gas emissions 20% or more than petroleum emissions were eligible to be added to gasoline or diesel. Surprise, a giant loophole existed. Ethanol plants in operation or under construction by mid-December 2007 did not need to comply. These grandfathered plants, exempt from emissions reduction requirements, have produced the majority of ethanol to date (GAO 2019). When all emissions are added up, ethanol releases up to twice as much green-house gas per unit of energy delivered as gasoline (Hertel et al. 2010; Mullins et al. 2011; NRC 2011; Searchinger et al. 2008; Plevin et al. 2010; NRC 2014; Liska et al. 2014). Find that hard to believe? Can you find research that says the opposite? Yes, you can. That is because what gets included in the growing, refining, and distribution of ethanol is not consistent between studies.
It’s just wrong to turn over 40% of the corn crop into fuel rather than food. This at a time when 43 million Americans need help with food stamps (USDA 2020).
We are running out of land to grow corn on, over a third has been lost in the past 25 years. Corn and soybeans already use up half of our crop land.
In 1949 there were 477 million acres of cropland (Nickerson and Borchers 2012) whereas in 2015, just 366.7 million (USDA 2018), a loss of 110.3 million acres. Cities took up 68 million acres of land in 2010, and are expected to grow to 163.1 million acres by 2060 (Nowak and Greenfeld 2018). Over 85% of sprawl happens near cities, which were originally built in the locations with the best farmland and water (Kolankiewicz et al. 2014).
The arable land we grow food and graze animals on has degraded so much that the United Nations estimates there are only 60 years of harvests left worldwide, on average. According to the UN, 95% of our planet’s land will be degraded by 2050, forcing millions to migrate as food production fails (FAO 2015b; Leahy 2018).
Corn and soy are 50 or more times more prone to soil erosion than sod crops like wheat, barley, rye, and oats. Why is that? It is because they are planted in rows much wider than other crops, up to 30 inches wide, a major highway for wind and water to barrel along and take topsoil with them (Al-Kaisi 2000; Sullivan 2004). This is exacerbated by heavy harvesting equipment that compacts and pulverizes soil into a fne powder that is more easily eroded and blown or washed away (RCN 2011; Mathews 2014).
Although there will always be miles of dirt and rocks beneath our feet, the living topsoil skin where crops can grow is thin and eroding 10–1000 times faster than in untouched nature (UNFAO 2015). This thin layer of soil is all that stands between us and starvation. An average of 12 inches is essential for crops to thrive (Evans et al. 2020). Dig below that and you hit death row, a subsoil desert without the rich organic matter plants dig their roots into to get the nutrients and water they need. The deeper the topsoil, ideally a foot or more, the more crops produced, and the cheaper the price to grow them (Al-Kaisi 2001). Soil grows back very slowly. An inch of fertile, organic topsoil takes 300 to several thousand years to create depending on what kinds of minerals are below in the subsoil (Bogard 2017).
Iowa has lost half its topsoil in less than 100 years, from an average of 18 to 10 inches deep (Klee 1991). Another study says it has gone from 14 to 18 inches deep to 6–8 inches (Needelman 2013). Illinois topsoil has also declined by half over a century. But why pick on Iowa and Illinois. All states are in the erosion club and have lost about half their organic matter since colonial times (Hopkinson 2017).
Civilizations before fossil fuels typically endured about 800–2000 years before they eroded their soil to the point where they collapsed. Today industrial agriculture is on track to crash civilization in just a few centuries. Mechanized plows introduced in the 1930s accelerated erosion by plowing the upper 6–8 inches of earth, exposing the soil to rain and wind. Gigantic tractors and other farm machinery with lots of horsepower have accelerated the loss, and some harvesters weigh more than the largest dinosaurs to walk the earth, the sauropods, compressing the soil so much less food can be produced. On average, this has led to 90 times more soil lost than formed (Coombs 2007).
Ethanol was mainly justified as causing less climate change than fossils. The Renewable Fuel Standard (RFS) of 2007 mandated that only biofuels which lowered greenhouse gas emissions 20% or more than petroleum emissions were eligible to be added to gasoline or diesel. Surprise, a giant loophole existed. Ethanol plants in operation or under construction by mid-December 2007 did not need to comply. These grandfathered plants, exempt from emissions reduction requirements, have produced the majority of ethanol to date (GAO 2019). When all emissions are added up, ethanol releases up to twice as much greenhouse gas per unit of energy delivered as gasoline (Hertel et al. 2010; Mullins et al. 2011; NRC 2011; Searchinger et al. 2008; Plevin et al. 2010; NRC 2014; Liska et al. 2014). Find that hard to believe? Can you find research that says the opposite? Yes, you can. That is because what gets included in the growing, refining, and distribution of ethanol is not consistent between studies.
The idea that biofuels generate less CO2 than gasoline stems from the fact that biofuels are derived from plants that absorb carbon dioxide. But land typically supports plant growth regardless of whether it is being used to grow corn or not. Corn grown for ethanol for use in gasoline has a net benefit of storing around 3 tons of carbon dioxide per hectare. But if the land had not been used for ethanol, we would be better off. If reforested, then 7.5–12 tons of CO2 would be stored per hectare. A corn ethanol field, formerly a forest, will emit 12–35 tons of CO2 per hectare a year for 30 years (NRC 2014). By contrast, a wetland stores 81–216 tons of carbon per acre (TCF 2020). In sum, corn does not sequester carbon but recycles it at best, releasing CO2 when made into ethanol, and absorbing CO2 in the next corn crop.
And here is the real kicker. Agriculture emits 80% of all nitrous oxide (N2O) with a global warming potential 300 times higher than CO2 and destroys stratospheric ozone while it is at it (Melillo et al. 2009; Mosnier et al. 2013). The use of fertilizer triggers these emissions. N2O emissions have increased substantially due to greater nitrogen fertilizer use, especially for corn, which uses greater amounts than most other crops.
Conclusion
Why does this loss of farmland matter from erosion, aquifer depletion, pollution and more? Pimentel and Pimentel (1990) estimate that given increasing soil erosion and declining resources—food, groundwater, pollution, forests, and fossil fuels—the ideal US population at our current standard of living would be 40–100 million people. Yet here we are at 336 million. Birth control anyone?
Creating ethanol for cars is destructive enough, and now even more corn for airplanes?
Sheer madness. Something has got to give, land, energy, and topsoil are limited resources. resources.
So would you rather eat, drink, or fly?
Or better yet, door #4: Get drunk on ethanol.
References
If any references are missing, you can find them in by books, especially Life After Fossil Fuels: A Reality Check on Alternative Energy
Alice Friedemann www.energyskeptic.com Author of Life After Fossil Fuels: A Reality Check on Alternative Energy; When Trucks Stop Running: Energy and the Future of Transportation”, Barriers to Making Algal Biofuels, & “Crunch! Whole Grain Artisan Chips and Crackers”. Women in ecology Podcasts: WGBH, Financial Sense, Jore, Planet: Critical, Crazy Town, Collapse Chronicles, Derrick Jensen, Practical Prepping, Kunstler 253 &278, Peak Prosperity, Index of best energyskeptic posts
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