Friday, October 5, 2007

A bit on bio-fuels

NPR's "Talk of the Nation" had a good piece today on the potential of cellulosic fuels, and the challenges in making them. Evan Ratliff:

On a blackboard, it looks so simple: Take a plant and extract the cellulose. Add some enzymes and convert the cellulose molecules into sugars. Ferment the sugar into alcohol. Then distill the alcohol into fuel. One, two, three, four — and we're powering our cars with lawn cuttings, wood chips, and prairie grasses instead of Middle East oil.

Unfortunately, passing chemistry class doesn't mean acing economics. Scientists have long known how to turn trees into ethanol, but doing it profitably is another matter. We can run our cars on lawn cuttings today; we just can't do it at a price people are willing to pay.

It's a very good article, well worth reading. Unfortunately, Mr. Ratliff didn't go as in depth on the idea of butanol. I've posted before, but here is a simple summary of the advantages that butanol offers:

Butanol has many superior properties as an alternative fuel when compared to ethanol. These include:

  • Higher energy content (110,000 Btu’s per gallon for butanol vs. 84,000 Btu per gallon for ethanol). Gasoline contains about 115,000 Btu’s per gallon.
  • Butanol is six times less “evaporative” than ethanol and 13.5 times less evaporative than gasoline, making it safer to use as an oxygenate in Arizona, California and other states, thereby eliminating the need for very special blends during the summer and winter months.
  • Butanol can be shipped through existing fuel pipelines where ethanol must be transported via rail, barge or truck
  • Butanol can be used as a replacement for gasoline gallon for gallon e.g. 100%, or any other percentage. Ethanol can only be used as an additive to gasoline up to about 85% and then only after significant modifications to the engine. Worldwide 10% ethanol blends predominate.

The real problem comes down to economics. The potential energy from cellulosic butanol is actually huge, but the cost per gallon remains a challenge. My own research on an algae based butanol production system has shown a lot of promise, but I haven't found a way to bring costs below $3.00/gal., which seems to be the magic number. The government and the big energy corporations have poured a lot of resources into ethanol, but they are going in a wrong (IMHO), albeit easy direction, making ethanol from foodstocks. There is a huge debate about the value of corn based ethanol that distracts attention from the other alternatives, such as butanol.

To be clear, I'm not saying that butanol is "the answer", but rather a potential part of solving the energy problem. We need cleaner sources for electricity, such as wind, solar, and tidal production. We need greater efficiency in all types of end usage. I'm merely working on one piece of a very large puzzle.

1 comment:

Anonymous said...

This is truly interesting material. I wish that the large companies and the gov't would take Wall Street style advice about energy.

Diversify. Diversify. Diversify.