- Posted on Thursday, February 14th, 2008 at 2:21 pm
More On Cellulosic Ethanol
GM Technical Fellow Candace S. Wheeler, Ph.D. took a moment to answer a question from a reader about our recent post on cellulosic ethanol. Thanks for the questions. Keep them coming. -Will Stewart, Blog Editor
Q. I have something to add to that: based on what I learned from GM folks today, they aren’t really interested in methanol, but I couldn’t get a concrete answer (except it just isn’t as efficient - which may be true since methanol is 50% the energy of gasoline, correct?) The Coskata process, though, makes cheap ethanol without the use of subsidies. That being said, it does seem like they could take their syngas and make methanol out of it, instead of ethanol. Do the GM guys have an answer to this? (Clayton B. Cornell)
A. The bacteria that Coskata use have been developed to specifically produce ethanol. This is an advantage since chemical catalysis of syngas gives a mixture of alcohols including methanol, which must be separated from one another. These other alcohols have some value as chemical co-products, but if made in large quantities would swap out the demand for these materials reducing their value and putting more of the processing cost onto the ethanol. China is looking at methanol as an alternative fuel, but besides the lower energy density that you mention, methanol poses some health risks if ingested or absorbed through the skin. It also has the same issues with absorbing water as ethanol, and therefore is not compatible with the existing infrastructure (pipelines). Butanol, a four carbon alcohol, does have a higher energy density and could be used in the existing infrastructure. There are bacteria which do produce higher alcohols such as butanol although, to date, the yield has not been as good as with ethanol and the butanol is often produced as a mixture of butanol and ethanol. Some strains of bacteria can even produce hydrogen which could be used as a source of renewable hydrogen for fuel cell vehicles in the future. As far as the Coskata process is concerned, they are currently focusing their efforts on ethanol production but do hold the patent on several other strains of bacteria for making other fuels.
4 Comments
Todd Witkowski
What ever happened to coal-to-liquids or gas-to-liquids technology? The Germans employed the Fischer-Tropsch process in WWII to derive diesel fuel from coal. The U.S. has more engergy in coal than Saudi Arabia has in oil. Imagine if all the demand for electricity in the U.S. was met by the latest in nuclear power technology - we would no longer need to burn coal, oil, or natural gas to generate electricity. We could use our vast coal and natural gas supplies as feed stock for ultra-clean diesel and gasoline fuels. And to think I didn’t even get into our vast resources of oil shale!
Paul Callahan
Hi, Todd,
All what you say is true. The Fischer - Tropsch process starts by making the same “syngas” used in the Coskata process but then forms desired molecules from carbon monoxide and hydrogen using chemical reactions as in an oil refinery. Syngas can be made from anything with carbon in it that will burn and some water to break down for hydrogen. Salt water will do.
The Coskata process looks to me to make liquid fuel more efficiently than the classic Fischer-Tropsch synthesis. I think there is less heat and byproduct loss, environmental impact, less potential capitol cost, etc.
If the regulatory powers that be decide at some point that the sythetic fuel industry shall use fossil feedstocks I suspect that the then existing syngas generators used for ethanol production could probably use lignite as a partial feedstock. Ditto for oil shale.
Right now is “zero net carbon” ethanol time.
GREG FORSHEE
Not sure if this is the right place to ask, but here goes.
I currently drive a 04 Chevy Cavalier that gets 37 mpg. The new 07 Aveo is rated at 34 mpg on the highway. I can’t understand why WE( GM ) can’t expect at least 40 mpg out of the Aveo if not 50 plus mpg using diesel hybrid technology( Izuzu?? )
William Stratus
CeEtOl or Cellulosic Ethanol is going to take off like a rocketship!! Ceetol together with new enzyme technology called the Bactranol process, can now be produced from municiple waste!! Investing in Ceetol has never been such an easy decision. Bring on the Ceetol!!
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