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More on Electric cars and trucks
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micronj
Posted 1/11/2019 13:17 (#7237632 - in reply to #7236842)
Subject: RE: More on Electric cars and trucks


Years ago there was a long article in Scientific American that covered energy efficiency (not costs) of various energy sources for automotive type applications. Gasoline, diesel, pure electric, hybrid, natural gas, hydrogen. Also the carbon footprint of each. I do not recall the numbers correctly, just throwing a few numbers out to show all the factors considered and a few that surprised me as a Mechanical Engineer. One was that something like 12% of all the energy in a barrel of oil is used in pumping, refining and transporting to you car gas tank. Took into account the energy efficiency of the combustion engine, etc.

Hydrogen. Normally made from natural gas. Bottom line was that you should just burn the natural gas in a combustion engine. Hydrogen from electricity, especially wind farms. Not practical to transport any distance. The pressure vessels are so heavy it said a semi load of hydrogen carried the energy equivalent of 300 gallons of gasoline.
Electric vehicles. Used national average of all electric sources, transmission line losses, power plant losses, etc. Total energy efficiency to the wheels was close to a good fuel efficient gas car. What surprised me was the CO2 output of coal fired plants were something like 2 x that of a natural gas fired electric plant.

You get the idea. Overall conclusions were for total energy efficiencies, a good efficient gasoline powered car was about as good as we could get with current technologies. Gas/ hybrid, maybe a slight bit better. Diesel was right in there but had other pollutant issues. Guess the point being, if there is one, is there are a lot of costs (energy losses, environmental) before it every reaches your vehicle that need to be part of the consideration.
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