Article 13742 of rec.autos.makers.vw.watercooled: Path: rochester!cornellcs!newsstand.cit.cornell.edu!ub!csn!news-1.csn.net!ncar!gatech!swrinde!howland.reston.ans.net!nntp.coast.net!lll-winken.llnl.gov!venus.sun.com!news2me.EBay.Sun.COM!eastnews1.East.Sun.COM!walters.East.Sun.COM!usenet From: sestina@East.Sun.COM (Mike Sestina - Sun BOS Hardware) Newsgroups: rec.autos.makers.vw.watercooled Subject: Re: Emissions/Cost of Diesel vs. Gasoline Date: 7 Mar 1996 19:53:42 GMT Organization: Sun Microsystems Inc. Lines: 65 Message-ID: <4hnes6$7j2@walters.East.Sun.COM> References: <313E2320.7E32@nannup.com> Reply-To: sestina@East.Sun.COM NNTP-Posting-Host: thing.east.sun.com In article 7E32@nannup.com, "Mark S. Handcock" writes: > Does anyone know how to compare diesel to gasoline engines > in terms of emissions (i.e., air toxics, CO2) and other > environmental concerns? The Volks. Passet TDI looks > interesting. Is it too good to be true? > > Mark A gas engine, running unleaded fuel without a catalyst, emits a mixture of carbon dioxide Co2, carbon monoxide Co nitrogen oxides NoX, unburnt hydrocarbon HC and some sulpher dioxides So2 The catalyst was invented to oxidize most of these but it is not effective until completely warmed up, effectively short trips are as if the catalyst were not present also in genreal the gasoline catalyst performs its function at the cost of increased fuel consumption over a non catalyst. compared to gas, a diesel engine puts out less Co2 less Co more NoX less HC particulate carbon (black soot) same or lower sulpher dioxides So2 the TDI has a catalyst for soot and Nox it requires lo sulfur diesel fuels and does not cause increase in fuel consumption environmental concerns? Carbon Dioxide Co2 - greenhouse gas Carbon Monoxide Co - toxic gas. Nitorgen Oxides NoX - reactions with sunlight and air to increas street level ozone (O3) the yellow smog that LA is infamous for. Unburnt hydrocarbons HC - bad stuff implicated in all sorts of things, such as smog, greenhouse effects, and even upper atmosphere ozone depletion Particulate carbon - harmless, once implicated as a carcinogen. further comparing gas and diesel: - the diesel will yield 15-25% better mpgs thats beneficial in itself because oil, however abundant today, is a finite resource and more importantly burning it increases greenhouse gasses VW claims their overall calculations show its new diesels contributes 30 % less to global warming then gasoline models - diesel fuel requires less energy to refine further lessening Co2 consequences of production - diesel fuel is not as volitile as gasoline less pollution from fuel evaporation and also less explosive hazard the pollution problems with any internal combustion engine is to remove the really nasty compounds without increasing the fuel consumption to such an extent that the increased carbon dioxide output negates the benefits. VW`s TDI look slike a winnner on this one.