On 20/3/2006, Peter Adderley wrote:
There's an interesting article at:
http://www.ecotalkblog.com/
which talks about a process developed in Germany in the early 1920,s
which converts coal into various "very clean burning" liquid fuels.
Would anyone be able to explain the "Fischer-Tropsch process" please?
Anthony Morton replied:
It's pretty straightforward in principle. You gasify the coal in an
oxygen atmosphere, breaking it down into 'syngas' which is a mixture of
carbon monoxide and hydrogen. Syngas is wonderful stuff because you
can use it to synthesise pretty much any kind of hydrocarbon fuel in
very pure form.
Unfortunately, you still have to suffer the tyranny of chemistry. Coal
has a higher ratio of carbon to hydrogen than any liquid fuel, so no
matter what process you use, if the result is to be liquid fuel you
have to remove some of the carbon somehow. In practice the 'excess'
carbon exits the process as carbon dioxide.
So you produce one lot of carbon dioxide in making the liquid fuel, and
another lot in burning it. Not terribly environmentally friendly -
unless of course you can bury the CO2 underground or somehow prevent it
getting into the atmosphere. But if you have a way to do that, then
what you're doing is not essentially different from burning the coal to
make electricity and using the electricity in a motor, which is all
possible with current technology.
Really the Fischer-Tropsch process is nothing more than a way to keep
liquid-fuel engines running when there's a scarcity of crude oil,
thereby postponing the switch to electrical technology and alternative
transport modes. It's not an 'environmental' technology at all: in
fact it's less environmentally sustainable than our current habit of
pumping crude oil out of the ground and refining it into liquid fuels.
And if sequestration of CO2 in large quantities somehow becomes viable,
we'd be better off environment-wise using electricity rather than
liquid fuel as the energy carrier anyway, even though it's less
efficient, because that way *all* the emitted CO2 can be captured at
the source.
