The discussion of whether Propane (LPG) is dirtier or cleaner than
gasoline, must include a mention of what engine it is burned in and
what emissions equipment the engine has. The whole point (as I
understand it) of setting up Morgans imported to the US to run on
propane in the late '70's and early '80's was that EPA required very
extensive testing on gasoline powered engines with catalytic
converters before they would approve an engine for sale here. Rover
had bailed out of the market in '72, came back briefly in '80 and the
Range Rover would not bring the V-8 with pollution controls back into
the market until '87? '88?
Under EPA rules at the time, a car could be run on propane with out
adding the catalyst and associated controls and testing requirements
were less extensive. I think it would be safe to say that some
emissions from a 1980 european spec. Rover V-8 would be reduced when
it is run on propane as compared to gasoline *without a catalyst*.
Add a catalyst and controls to the gasoline V-8 and some emissions
would probably be less than those from the propane V-8.
Here is more "fuel" for thought -- an excerpt from Steering a New
Course: Transportation, Energy, and the Environment, 1991:
"When LPG is made from natural gas, the CO2-equivalent emissions may
be slightly lower than those from gasoline. When LPG is made from
crude oil, however, CO2-equivalent emissions may increase slightly.
Depending on the air-fuel ratio, CO emissions are usually lower than
those for gasoline because of the complete mixing capability of
gaseous fuels. Hydrocarbon emissions from LPG vehicles are about the
same or lightly higher than those for gasoline, and less reactive,
depending on the emission-control system in place. NOx emissions are
most likely to be increased because LPG fuel systems do not interact
wiht current three-way catalyst emission control systems (DOE 1988a)."
Elsewhere in the book they say that SOx emissions are also lower with
LPG compared to gasoline, but I don't know if that depends on the
presence of a catalyst -- I would guess not. I've considered
converting one of my Rovers to CNG or LPG, so I'd be interested in
data comparing emissions from different fuels used in a given engine
without emissions controls.
Whatever one may think about emissions from propane engines, I have
heard from reliable sources at the Morgan factory that they are happy
that Bill Fink/Isis Imports kept them in the US market with the
propane conversion before Rover re-entered the market with an approved
gasoline engine.
--Steve Manwell
smanwell@xenergy.com
'54 +4, '64 Rover 3 litre, '68 2000TC
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