alt.energy.renewable

-> What kind of coal? Anthracite? Lignite?
-> What kind of plant? Combined cycle plant, or single cycle?
-> How thermally efficient is the diesel engine? How would it compare
-> with a suitable electric engine?

Coal is almost 100% carbon. This is true of all types. Oil, on the
other hand, consists of compounds of carbon and hydrogen. When they are
burned, all the energy from the coal comes from converting the carbon
and oxygen from the air to CO2. The energy from burning oil is partly
derived from producing water vapour from the hydrogen. As a result, for
every joule (or whatever) of energy that is produced, something like
twice as much CO2 is formed by burning coal than oil.

Electric motors are highly efficient at converting electric energy to
mechanical energy. But at the power station, if it is a "thermal" one
(as opposed to hydro-electric, etc.), there has to be a heat engine
that takes energy from a flow of heat and turns it into mechanical
energy that drives the electric generator. *That's* where the overall
system is seriously inefficient, although there are also losses in
transmitting the electricity from the generator to the train, etc..

dow