From: jeremy@classic.asd.sgi.com (Jeremy Higdon)
Subject: Re: Environmental cost of transportation (was Re: SFO rail transit setback?)
Organization: Silicon Graphics, Inc.  Mountain View, CA
Distribution: ba
Date: Mon, 14 Dec 1992 08:18:34 GMT

In article <Bz4pKG.BEH@taligent.com>, Rick_Donnelly@taligent.com (Rick Donnelly) writes:
> 
> Public transit is not entirely free of blame for pollution either.
> 
> When I was at Sequoia Nat'l Park this summer, I saw a display that said
> that 60% of ozone-producing emissions from vehicles came from diesel trucks
> and buses, _not_ cars!  Most public transit in the Bay Area is provided by
> diesel buses.  To the best of my knowledge, none of the Bay Area transit
> agencies even have _pilot_ programs in place to replace these diesel-
> belching bus engines with engines that burn cleaner fuels, like methanol
> or compressed natural gas (or even gasoline!).  The conversion cost is not
> that great. (Denver RTD was ordered by the Colorado AIR Board to replace
> _all_ its diesels with methanol-powered buses within 10 years or so, and
> RTD didn't complain about the cost. They started the replacement right away,
> and started bragging publicly about the resulting air quality benefits.)
> 
> Does anyone know why the transit agencies in the Bay Area aren't doing
> anything like this??  Does anyone have suggestions on ways to get them
> to start converting to cleaner fuels?  (I've already complained about
> this to the BAAQMD, but I got the impression that my complaint fell on
> deaf ears.)

The Denver RTD has only a pilot program going so far, using a few methanol
buses.  Methanol has real problems that make it not really a better option
than diesel, in my opinion.  The best alternative is probably going to be
CNG.  Sacramento RTD just received a batch of CNG buses.  SCRTD is
purchasing methanol buses in large quantities.  The main problem with all
of these alternate fuels is that the vehicles burning them cost
substantially more to buy, maintain, and run, at least for now.  CNG also
requires expensive new fueling facilities.

But new diesels aren't that bad.  The emissions of HC, NOx, and particulates
are all dramatically less than vehicles of as recently as the mid 80's.  And
particulates are dramatically lower in new '92 model vehicles.  In the 80's,
the limit was around 1.1 grams per brake horsepower hour.  In 1990, it went
down to .6.  For '91 it dropped to .1 (though there weren't any certified
engines, so I think transit agencies got waivers on many 1991 buses -- also,
SCCTD put its 1990 model buses into service in April 1991).  In '94, it will
reduce even more, though it's not clear what the manufacturers will be able
to do.  .05 g/bhph is the goal, about 5% of what a 1986 bus emits.

Another problem that the pre-87 or pre-88 buses had was that their throttle
delay systems would fail, causing them to emit quite a lot of black smoke
upon starting up.  Theoretically, this should be easy to fix, but since
the bus accelerated quite a bit more rapidly, many TA's apparently decided
not to.  In any case, buses from 87 on have electronic controls, so this
doesn't happen anymore.

Finally, I would guess that by the end of the decade (barring unforeseen
circumstances), all new vehicles will be CNG powered.

jeremy

Xref: sparky ba.transportation:2865 sci.environment:13715 ca.environment:1104