[SGVLUG] [OT] Especially for Tom & his Prius.... [my rebuttal, then I'll shut up]

[David Lawyer]

On Mon, Jul 10, 2006 at 11:59:45PM -0700, Dustin Laurence wrote:
Regarding CO2 emissions.
> For ordinary fossil fuels like gasoline and diesel only MPG matters.

Wrong.  A gallon of diesel fuel has about 11-12% more carbon in it
than a gallon gasoline.  That partly explains while diesel has 138,700
BTU/gal vs. 125,000 BTU/gal for gasoline (all using the higher heat
of combustion).

Furthermore, diesel has slightly more carbon per BTU content than
gasoline.  Transportation Energy Data Book Ed. 24, Table B.16 shows
Distillate fuel (diesel) at 19.95 million-metric-tons-carbon per
quadrillion-BTU.  Motor gasoline is only 19.34.  Note this unit of
measure is the same as kg-carbon/million-BTU.  (Don't know why they
used such a "large" unit.)  Of course the weight of the CO2 is greater
than the weight of the carbon alone since there is also the weight of
the oxygen.

When comparing diesel and gasoline MPG, you need to convert the diesel
MPG to equivalent gasoline MPG by reducing the diesel MPG figure by
about 10%.

			David Lawyer