The Oil Drum

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Robert,

I want to thank you for all the time and effort you have expended in getting to the truth about peak oil and the ethanol hoax in particular. Your fair-minded efforts have made a real difference in the energy policy in the U.S., if nothing else I believe you've slowed down the implementation to where wiser heads will stop the ethanol insanity hopefully before there is so much investment that its unstoppable.

The historic debates on whether and by how much the energy gain of ethanol was positive have been a red herring. Irrespective of that bottom line, the other limiting inputs to corn ethanol make it far inferior to gasoline. Even if cellulosic ethanol lives up to its claims of higher energy return (which I find doubtful because the initial ethanol solution is less concentrated than with starch ethanol) it will still have the scalability problems of other limiting inputs.

But it is natural to want to find a 'replacement' for something, in fact we are conditioned to do so. In the end, changing our way of life and moving away from the internal combustion engine will serve us much better than scaling up land, material, soil and water inputs to create an inferior fuel. But it will take time for this message to sink in, because its a very difficult one (at first) to accept.

I'm mostly concerned about water. David Pimentel told me the Kreider study seriously understates the amount of water needed for corn ethanol, which is presumably a boundary issue which Im trying to suss out.

About 10.2 kg of corn is required to produce 1 gallon of ethanol. The average water requirement per kilogram of biomass is 1,000 liters. In Pimentels latest water paper they report that 650 liters of water are required to produce 1 kg of corn. This means 6630 liters of water for just the corn in 1 gallon of ethanol - or about 1754 gallons of water. And still a little more water is required in the fermentation and processing operation.

Water, like oil, is seemingly cheap, unless one lives in Western US. As nasty as oil and gas production are, they at least limit their environmental impacts to small land areas relative to biofuel production.

Systems analysis at the highest levels of government needs to address the linkages between water and energy. Fully 50% of our nations water use goes to the energy sector already. If we scale non oil and gas energy sources - what will this mean for water? In the end I think most of us would rather drink than drive...

The section on cellulose ethanol is weak. Soy beans are more likely to be made into biodiesel. If (a very big if) cellulose ethanol ever becomes commercially viable, the raw material could be wood residues, garbage or native species with a low impact on soil such as switchgrass.

Burning biofuels impacts the nitrogen cycle. When you take dinitrogen from the atmosphere and convert it to n02 and n03 you are increasing the local concentration of fixed nitrogen in the air and soil. This has all kinds of negative impacts on the environemnt.

Robert:

I am not a big fan of ethanol, but I do believe that there is another ethanol feedstock worthy of further study: sweet sorghum.

As you know, the EROI for ethanol from Brazilian sugar cane is far superior to that of ethanol from US maize (corn). I have seen EROI figures in the range of 3-4, but there has been so little research wrt sweet sorghum that I don't know how firm those figures may be; one would intuitively assume that the EROI falls somewhere between maize and sugar cane. This in turn suggests that the EROI for sweet sorghum would be at least 2-3 times higher than for maize. Given that maize ethanol is barely more than a break-even proposition, this certainly suggests that if we are going to do ethanol at all, sweet sorghum is worth a closer look.

An important reason why I think that sweet sorghum warrants further study is that its culture is very similar to that of maize, but perhaps not so input-intensive. In the Southern Appalachians, where I live, one sometimes sees maize and sweet sorghum growing adjacent to each other; to the uninitiated eyes, the crops look almost identical. The important difference is the absence of vulnerable ears of grain in the sweet sorghum crop. Massive inputs of fertilizer, water, and pesticides are required for maize plants to produce high yields of grain. In contrast, the sweet sorghum plants need only grow the stalk, which is far less vulnerable to pest damage and is less demanding of water and fertilizer. Because the crops are so similar (differing in their culture only at harvest), it would not be too difficult a transition for farmers to switch from growing maize to growing sweet sorghum. Harvesting at large scale would require different equipment; however, the harvesting equipment is inherently less complicated than that required to harvest maize.

One obvious disadvantage of sweet sorghum over maize is that it cannot be stored for a long period of time. The juice must be extracted from the stalks (traditionally done by a simple crank press, which could be scaled up to industrial levels) fairly soon after harvest. To make sorghum syrup, considerable energy is required to boil the juice down. More likely, the juice would not need to be concentrated to that level in order to become a suitable feedstock for a fermentation process. I am not certain how long such juice could be held in storage prior to being fermented, but there must be an optimal level.

Which raises the other obvious disadvantage: existing maize ethanol production facilities would require substantial retrofits to process sweet sorghum. I suspect that at least some of the installed distillation equipment would still work, but there might need to be some reconfiguration. The bigger problem would be the need to process the entire year's crop in a short period of time. Existing processing facilities have been built on the assumption of a year-round supply of maize feedstock. This might be an argument for concentrating the sweet sorghum juice to a higher level for storage, and then diluting it as needed. This in turn would then also require the construction of large storage tanks. All of this weighs against and reduces the EROI, but probably still results in a higher EROI than maize ethanol.

As I said, I'm not a fan of ethanol. But it does appear that political pressures are going to dictate that a substantial quantity of ethanol be produced, and produced from feedstocks grown in Midwestern farm states. Because sweet sorghum could be grown in those same farm states and promises a better EROI than maize ethanol, we ought to at least take a good look at it from a damage control perspective if for no other reason.

Robert unimaginable scale has unimaginable environmental impact. To grow corn for all our gasoline needs would require 978,261 square miles. To replace our all crude petroleum would require 1,200,000 square miles of corn, or 1/3 of the United States of America. Put another way, all our corn converted to ethanol only accounts for 19% of our gasoline.

I am inclined to think that the most insidious environmental harm is the fact that ethanol is believed by the general public to be a "solution" to the oil problem such that nobody will need to make any changes to their lives other than to buy a flex-fuel car.

Clean (very low emissions) thermochemical processes like pyrolysis and gasification can be used for the creation of syngas (CO and H2) that can be combusted in place of natural gas. They don't require any water and to a great extent the feedstock supplies the fuel for continuing the thermal process.

According to the DOE, syngas can also be catalyzed or fermented into ethanol and other higher alcohols. The heat from the reaction can be captured to generate electricity. The yield is projected to be between 70-125 gallons per ton of feedstock based on pilot plant results.

Feedstock can be anything containing C-H-O including: fossil residues like petcoke; automobile waste like autofluff and tires; forestry wastes from the forest products industry; ag wastes like stover; decaying tree residues from wildfires and bug infestations; municipal solid waste; sludge; etc., etc.

This means that clean biofuel production creates a profit stream for solving a multitude of environmental problems and catastrophes.

These are the technologies that I am watching - not corn fermentation. I am not particularly enamored with enzymatic hydrolysis either but I am willing to support the research because the rate of technological development is much faster than ever before thanks to personal computers and communications.

I am inclined not to rule anything out under the circumstances.

I am amazed that the oil industry has not built any refineries in the U.S. for thirty years. Surely there have been some leaps in innovation that could be better deployed in a new facility rather than retrofitted to an old one.

I wrote the article on Peak Soil you refer to above (latest version at http://www.energyskeptic.com/Peak_Soil.htm ), and there are some additional unsustainable, environmentally damaging aspects to growing any kind of plant for biofuels you didn't mention above:

1) Soil Biota

Soil creatures and fungi act as an immune system for plants against diseases, weeds, and insects – when this living community is harmed by agricultural chemicals and fertilizers, even more chemicals are needed in an increasing vicious cycle (Wolfe 2001).

2) Soil compaction

Plants and creatures underground need to drink, eat, and breathe just like we do. An ideal soil is half rock, and a quarter each water and air. When tractors plant and harvest, they crush the life out of the soil, as underground apartments collapse 9/11 style. The tracks left by tractors in the soil are the erosion route for half of the soil that washes or blows away (Wilhelm 2004).

3) Soils store more carbon than the atmosphere and vegetation

Soils contain 3.3 times the amount of carbon found in the atmosphere, and 4.5 times more carbon than is stored in all the Earth’s vegetation (Lal 2004). If we want to reduce global warming, storing carbon in the soil will be essential. But that will be hard to pull off, because Climate change could increase soil loss by 33% to 274%, depending on the region (O'Neal 2005). Intensive agriculture has already removed 20 to 50% of the original soil carbon, and some areas have lost 70%.

3) Continuous corn increases global warming by 71% (Powers 2005)

4) Destruction of CRP land, hardwood forests, wetlands, and range land to grow more biomass (and food) will reduce stored carbon & biodiversity

Farmers want to plant corn on highly-erodible, water protecting, or wildlife sustaining Conservation Reserve Program land. Farmers are paid not to grow crops on this land. But with high corn prices, farmers are now asking the Agricultural Department to release them from these contracts so they can plant corn on these low-producing, environmentally sensitive lands (Tomson 2007).

Population in the United States could reach over one billion people by 2100 (U.S. Census Bureau 2000), so what will happen is that we'll need more crop land and have to cut down bottomland forests and fill in wetlands to grow food, which will reduce stored carbon and biodiversity even further.

Deforestation of temperate hardwood forests, and conversion of range and wetlands to grow energy and food crops increases global warming. An average of 2.6 million acres of crop land were paved over or developed every year between 1982 and 2002 in the USA (NCRS 2004). The only new crop land is forest, range, or wetland.

5) Fertilizers increase global warming, acid rain, and eutrophication, but they provide no ecosystem services like organic matter (a.k.a. "waste" biomass), such as putting carbon back into the soil, increasing soil structure to let air and water to plant roots, pr