By analogy, it’s like the nuclear fusion estimations. Several times, the reactors they built didn’t quite cut it, but their understanding of the process led to the International Thermonuclear Experimental Reactor (ITER), which is expected to turn an energy profit. So we may indeed come across unexpected energy costs here and there that will reduce the promised energy gains.

Some variables that might also be overlooked are the energy costs of transporting the feedstock to the refinery, and returning nutrients to the soil.

Just thought I’d add to the pile. Glad it’s of use to you, Mike!

Thanks, Mike

In the case of energy use, the over-estimates take a little too much into account, and have left certain things out. David Pimentel at Cornell did a study that included the fuel cost of ethanol plant workers’ sandwiches – as if they wouldn’t eat lunch if they didn’t work at such a plant. He also left out the energy savings of byproducts of corn grain ethanol such as distillers grains, which can be fed to cattle.

I don’t know of any significant under-estimates, but I do know that Dan Kammen at UC Berkeley estimated that ethanol does turn a modest energy profit at its current state, when you take into account the byproducts that can be of use.

As Anastasia mentioned, the non-grain part of the corn plant can be used as a feedstock for cellulosic ethanol. I know some researchers that have corn that produces tons of tillers on the bottom of the plant, increasing the biomass of the corn. The idea is that you can keep the grain and turn the rest of the plant into ethanol. It could make the Food vs Fuel debate a non-debate.

There’s another thing to consider, too, when it comes to Greenhouse Gas emissions, that oil as-it-is takes about as much energy to process and transport as you get out of it at the end. So a gallon of gas is worth two gallons worth of emissions. A modest energy profit with biofuels doubles the actual GHG emission reduction.

Interestingly, a lot of the problems you bring up can be solved with genetic engineering.

First, the amount of energy needed to produce ethanol (and gasohol, biodiesel, etc) is coming down each day as more and more research takes place. One of the biggest advances is in engineering bacteria that can more effectively breakdown carbohydrates (especially that stubborn lignin) into types of fuels that require less processing. It was even on the Colbert Report last week. Biofuels won’t fulfill all of our energy needs, but I think they have a place alongside wind, solar, maybe nuclear, and things that haven’t even been invented yet.

Second, there’s tons of research on feedstocks (the stuff that gets turned into biofuels) from algae to perennial polycultures of native grasses. It’s unlikely that the same feedstock will work everywhere. For some places, corn stover will make the most sense, in others algae, trash, or a combination of these and more. Of course, I know more about what’s happening in the world of corn. With breeding and genetic engineering, the carbohydrates can be stored in forms that are easier to make into fuel. I just learned of some work on a mutation that increases biomass that doesn’t seem to have a negative impact on grain production. And, there’s a lot of work on checking how much stover can be safely removed from different types of fields without damaging soil carbon or causing erosion.

Third, Nitrogen Use Efficient, or NUE, corn is just about ready to go, although the regulatory process will frustratingly still take about 3 years. This will decrease the need for nitrogen and decrease run off. Of course, I’d rather see NUE combined with more sustainable farming practices in order to have the most positive effect. I wonder if anyone is working on PUE or KUE. I hope so.

I am just curious if there are avenues in GMO to deal with these questions.