Ask Pablo: Diesel vs. Hybrid, Which Is Better? : TreeHugger
Diesel: Reputation vs. Reality
Diesel engines work differently than gasoline engines. Rather than relying on spark-ignition to ignite highly flammable gasoline, the diesel engine uses compression-ignition, basically compressing a mixture of air and diesel fuel until its combustion is induced with the help of a glow plug. Diesel engines have a very high compression ratio and therefore have the highest thermal efficiency of any internal combustion engine. You would be forgiven for associating diesel engines with plumes of black smoke pouring out of mufflers. Recent legislative advances have drastically improved the fuel standards for
Ultra Low Sulfur Diesel (ULSD), cutting down exhaust emissions (non-greenhouse gas emissions like SO
x) by 90%. New pollution control technology also helps reduce emissions from the tailpipe. The engine that was once associated with poor air quality and smog is now approaching the emissions levels of gasoline engines. Diesel fuel does have a higher carbon content that gasoline and results in 22.2 pounds of CO
2 per gallon compared to 19.4 for gasoline.
Hybrid: Reputation vs. Reality
Hybrid vehicles have gained an aura of “greenness” and the popularity of the Toyota Prius has been fueled by
conspicuous consumption. Car commercials promoting hybrids have tried to give the impression that driving a hybrid is equal to doing something
good for the planet, when in reality it just amounts to doing something
less bad. Driving an SUV is still consuming a lot more gasoline and emitting a lot more greenhouse gasses than is really needed to transport its solitary occupant from point A to Point B, even if that SUV is a hybrid. So let’s be clear, hybrid cars are a step in the right direction but they are not the solution to the challenge posed by climate change.