Cellulosic Ethanol

Dual-fuel gas station at Sao Paulo, Brazil.
Image via Wikipedia

Last summer I shared my thoughts on biofuels, specifically E85. In short, yes they can offset our dependence on foreign oil, but because biofuels contain less energy per gallon than gasoline we’ll need more of it to keep up with our current consumption rates, and this solution completely neglects our need for more efficient cars.

There is a process that can produce E85 with the waste from other manufacturing processes that involve plants. This uses the plant material left over from other types of farming such as sugar or corn and uses the stalks, straw, wood, etc to make cellulosic ethanol. Cellulose is present in all plants, so there’s plenty of this material available, and humans can’t digest it, so this will never be a source of food for us. Plus, this uses the waste of other processes, so it wasn’t being used anyway. This negates the argument about growing for food versus fuel. Also, because this is a biofuel, it burns cleaner than petroleum based fuels. So far so good, right?

There are a couple of snags hidden in the details. First, the process of turning plant material into something you can burn in your car is not very efficient. With today’s technology we’d need A LOT of plant material to make enough E85 to make a dent in our foreign oil consumption, more than required to make corn ethanol. What this means is that if we’re going to look at this as a large scale source of energy, the waste from other manufacturing processes won’t provide enough raw material to work with. We’ll need to grow plants for the purpose of putting fuel in our cars. The food versus fuel argument is not solved.

And there’s more. Cellulosic ethanol is estimated to cost $2 per gallon, about the same as gasoline. Because its ethanol, a tank full of this fuel still won’t take you as far as a tank of gasoline, so the net cost to the consumer will still increase. The takeaway is that this has the potential to drive both food and fuel prices up. That’s not exactly what I have in mind when looking for alternative energies.

If you’re a die hard green energy proponent higher prices may not be enough to deter you, you want cleaner energy regardless of cost. Okay, lets look at this from another angle. Think of all the engergy required to grow, harvest and manufacture cellulosic ethanol. Tractors are needed, electricity to run the plant, fuel to distill the final product. Apart from the land devoted to grow the raw material, each of theses processes require energy. Today that energy is provided by petroleum based products. In other words, non-green energy is being used in the production of a green biofuel (what the???). If the manufacturers switched to burning ethanol in their processes so that this fuel were green from start to finish, they would still be burning fuel to make fuel, but because ethanol contains less energy per gallon they’d need to burn more of it and the cost of production would increase. Cellulosic ethanol would then become more expensive than gasoline. I’ve read that cellulosic ethanol burns clean enough that green house gases are reduced by 90% when compared with petroleum products. I question that stat, but even if true, because of the amount of energy required to produce the fuel it’s not enough. It would be more expensive and we’d still be polluting the atmosphere.

Keep in mind that there’s a good chance that your car is not capable of burning E85 as is. If you want to take advantage of E85 you’ll need to convert your engine which costs anywhere between $500 and $1,000. And, keep in mind that you’ll be spending more for fuel than you would if you chose to burn gasoline.

So lets put all of this together. If cellulosic ethanol becomes available in my neighborhood next year, I may be tempted to burn it instead of my regular gasoline. I’ll pay to convert my Nissan Maxima to burn E85. Then, I’ll fill my tank up. The cost will be about the same as what it costs me to fill up with gasoline, but instead of getting 300 miles per tank, I’ll only be able to drive about 250 miles. Plus, I’m buying a fuel that displaces land used for food production, and a lot of energy was used to make my E85.

I’m a strong proponent of alternative energies, for both political and environmental reasons. I think its smart for us to consider all kinds of solutions to our energy needs. Plus, as an engineer I appreciate that as a country we’re pursuing new technologies. There are two things that I object to about cellulosic ethanol. First, the media and biofuel evangelists tout this as the solution to all of our problems, and that’s just not the case. This doesn’t fully address our dependance on foreign oil, and it isn’t a boon for the environment either. At best, its trading one set of problems for another. And second, our government is pumping millions upon millions into this industry. I just don’t see this paying off. I’m in favor of smaller goverment, so honestly I wish they would leave this to the private sector, period. Since that isn’t a reality I wish they would at least shift some of the funds into other solutions, like nuclear fusion or geothermal energy, a smart power grid, improving wind energy storage… there are many other solutions more promising than biofuels.