26-12-2012, 04:44 PM
Comparative Energy Consumption (in MJ per vehicle km)
Comparative Energy.ppt (Size: 133.5 KB / Downloads: 25)
Toxins identified in Diesel Exhaust by the EPA
Diesel Exhaust is a complex mixture of hazardous particles and vapors, some of which are known carcinogens and other probable carcinogens.
The US Environmental Protection Association (California) has identified 41 substances in diesel exhaust listed by the State of California as” toxic air contaminants”.
A “toxic air contaminant”is defined as an “air pollutant which may cause or contribute to an increase in mortality or in serious illness, or which may pose a present or potential hazard to human health”.
In addition to, or as part of the commonly referred to emissions of NOx, CO and particulate matter produced by diesel engines, the substances listed at the left have been identified.
The immediate health threat posed by the use of diesel engines in transit buses arises from the fact that the toxic emissions are released directly into the streets--right into the airways of pedestrians and transit patrons waiting at bus stops.
Studies of emissions from co-called ‘clean’ diesel engines reveal that, while NOx and CO levels may be lower, the levels of toxins such as dioxins, benzene, toluene, 1,3-butadiene and PAH’s is essentially unchanged. While the weight of the particulate matter is reduced substantially, the total number of particles emitted by ‘clean’ diesel engines is 15 to 35 times greater than by conventional diesels. The particles are simply finer, not fewer. Finer particles are more likely to penetrate deeper into the lungs, where they would be trapped and retained.
Fuel Cells and GHG’s
Hydrogen needed to power fuel-celled vehicles is most readily obtained by stripping it from hydrocarbon molecules found in fossil fuels. The process results in the release of Carbon Dioxide, the most common greenhouse gas and the key target of the Kyoto Accord. Presently, fuel cells would result in little reduction in greenhouse gases over internal combustion engines.
The chart below quantifies the greenhouse gas emissions produced in operating a Mercedes A-class automobile with different power sources: