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Friday, February 13, 2009

Wishful thinking

(phrase) Hoping for a socially good outcome when evidence suggests otherwise.


The United States has enough land, water and transport capability to make cellulosic ethanol that could displace one-third of its gasoline needs in 2030, according to a study by a government laboratory, in partnership with General Motors.

But the study does not say how to actually make the fuel.
  [end trite transmission]

I work in the renewable energy field and have a fair amount of experience with technology adoption and policy strategies.  Cellulosic ethanol (ethanol from grasses, trees, waste instead of corn) is hailed as the solution to getting off foreign oil, using cleaner fuel, and avoided the (specious) food v. fuel debate.*

The problem is that nobody knows exactly how to do it.  We have options:

a) break down the biomass with acid and enzymes to release the complex sugars, and then ferment sugars to make ethanol.  Problems: you need very uniform feedstock because it's difficult to engineer an enzyme that works with many different kinds. 

b) gasification.  We can gasify biomass and create various compounds that can be cracked (a la refineries) into various products.  Ethanol is not really the first thing you get, but it can be made from the gaseous products.  This system has a higher capital cost than (a), which is already at least five times higher than corn ethanol.  Plus, it may actually be easier to turn biomass into diesel than ethanol - although this makes integration into our fuel mix easier, it does not make our fuel any cleaner.

In short, we are hinging our hopes for fuel independence on a technology that is very complex, has yet to reach commercialization, and for which we have no readily available production and distribution network.  Corn ethanol, anyone?

*Note: ethanol from corn can contribute to an increased price for feed corn, which can in turn increase the price of meat and processed food, including such goodies as high fructose corn syrup.  If you combine the American obesity epidemic with Economics 101, this is a Good Thing.

*Other note: the major problem with corn ethanol is that growing corn is a fossil fuel intense activity.  The energy return on energy invested is positive, but not by much.  Research suggests we get - at best - 2 units of energy back for every 1 we put into corn ethanol.  Oil returns 10-to-1, so modern civilization is going to slow down a lot if we have to rely on corn ethanol for transportation.

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