George Olah holds the Donald P. and Katherine B. Loker Chair in Organic Chemistry at USC and is the 1994 winner of the Nobel Prize in Chemistry. His new book examines what he believes is the vastly superior potential for methanol as a future transportation fuel over ethanol or hydrogen.
MIT's Technology Review ran an interview with Professor Olah as did NPR's Science Friday. Note that the NPR interview is long and rambling so, even though I linked to it, I actually do not recommend listening to it.
We all know why a replacement for gasoline is needed. We do eventually need to transition to a fuel source that is renewable. The strategies currently under discussion for replacing gasoline are predominately hydrogen and ethanol.
The problem with hydrogen is (from the Technology Review interview):
Even today you could put a pump dispensing methanol at every gasoline station. You can dispense it very well without any [new] infrastructure. For hydrogen, there is no infrastructure. To establish a hydrogen infrastructure is an enormously costly and questionable thing. Hydrogen is a very volatile gas, and there is no way to store or handle it in any significant amount without going to high pressure.
So hydrogen is volatile (strike one), has to be stored under high pressure (strike two) and the required infrastructure would have to be built from scratch (strike three).
What about ethanol?
Well, the problem with ethanol are the limited number of ways of producing it economically. Arguably, there are actually no ways of producing it economically, since current estimates are that ethanol production requires energy input somewhere between 90% and 100% of the energy output. Some even claim that it takes more energy to produce ethanol than we get out of it, although scientists seem to have settled on a consensus that there is a small energy surplus created in the process. (The energy comes from photosynthesis, so this is not a violation of conservation of energy.)
The very nice thing about methanol is the number of different ways it can be manufactured. One of the things Professor Olah points out is that "the needs are so enormous that biological sources per se won't solve them". Methanol can be produced from any cellulosic material — wood, grasses, hemp, etc. — and, in fact, methanol is also referred to as "wood alcohol". However, methanol can also be produced from natural gas and, most importantly, directly from electricity through a fuel cell process.
As Professor Olah explains:
This fuel cell uses methanol and produces CO2 and water. It occurred to us that maybe you could reverse the process. And, indeed, you can take carbon dioxide and water, and if you have electric power, you can chemically reduce it into methanol.
So all you need to produce methanol is air, water and electricity. This means we now have a way of safely and efficiently storing electricity produced by solar, wind, nuclear, hydropower or any other method of production. Take that, batteries! (In fairness, the process works much more efficiently with higher concentrations of CO2, so you would probably use flue gasses at power plants, rather than just plain air.)
Of course there will be energy loss, so it is still preferable to use electricity directly when you can. But what this means is that we now have a method of plugging renewable energy sources — which often produce electricity directly — into the automobile fuel production pipeline. I have not seen an analysis, yet, and hopefully Professor Olah's book goes into it further, but off the top of my head it seems like this would be a much more efficient way to create a solar powered car than using the heavy, extremely inefficient batteries we use today. Its probably especially efficient if the car uses a methanol fuel cell, rather than burning the methanol in an internal combustion engine. Note, though, that methanol can be burned in today's automobiles — no need to retool the automobile industry to use this technology.
To close the loop on the ethanol vs methanol question, methanol can actually be converted in ethanol, but at a cost in energy. Professor Olah did not say the following outright in either of the interviews, but he seemed to imply that because of energy losses in the conversion, it would be more efficient to burn methanol directly, hence why he prefers methanol over ethanol.
In doing a little research for this posting, one of the troubling things I found is that methanol seems to be reasonably toxic, which seems to be one of the reasons why opinion leans towards ethanol as the preferred fuel. The other reasons why ethanol is currently favored are the higher energy density of ethanol (slightly higher than methanol, although still about 60% of traditional gasoline) and the political strength of the agriculture lobby.
If I ever get around to reading Professor Olah's book, I'll be sure to post an update. I'm a little behind on my reading, though, so its probably not on my list for the near future.