> Natural gas is the cleanest of all the fossil fuels. Composed
> primarily of methane, the main products of the combustion of natural
> gas are carbon dioxide and water vapor, the same compounds we exhale
> when we breathe.

I haven't looked into it, but I would think that there are other
(polluting) products of burning natural gas; the hydrogen and carbon
in CNG may well combine with atmospheric elements to produce nitrogen
dioxide (NO2) etc. The more so if the CNG isn't pure, and often
contains hydrogen sulfide. Sure, contaminants can be scrubbed out, but
commercial processes are unlikely to get it all out (for economic
reasons). Says he who a few weeks ago was collecting fossils from a
canyon cut into H2S-reeking methane source rocks.

 Also CNG cars are literally bombs. Propane (LPG) is far safer, not
that it's SAFE or good. Hydrogen is the only nonpolluting fuel, though
it's entirely unfeasible for cars, as well as being hydrogen... bombs.

Of course production of CNG and LPG is less complex and/or
energy-demanding than that of electricity, hydrogen, gasoline or
distillates ("diesel").

Oh, natural gas isn't a fossil fuel; there's nothing "fossil" about
it. Same with other hydrocarbons. Only COAL is fossil. And don't argue
with me, I'm a paleontologist.

:-)

--
Andrew Grebneff
Dunedin, New Zealand
Fossil preparator
Mollusc, Toyota & VW van nut
Temporarily in Calgary, AB, Canada
<goose1047@gmail.com>