Internal Combustion Engines Are Still 85% Inefficient

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You might be surprised to hear, that after all this time, with so many compelling reasons to make vehicles more energy efficient, that the internal combustion engine still only uses 15% of the energy it receives from gasoline. I sure was.


A century ago, when the internal combustion engine was invented, climate change and peak oil were hardly on the radar. But even today, a century later, with all we know now, a solid 85% of the energy derived from oil is still wasted on the gas car.

According to the EPA, 62% of that loss is right in the drive line.

About 17% is wasted in idling. Braking wastes 5.8%. Friction between wheels, bearings loses 4.2%, air resistance 2.6% and stereo, A/C and power windows use 2.2%.

Electric vehicles will finally re-enter the market this year in the US. EV technology was abandoned quickly a century ago, with just the installation of a few trolley car systems around the nation (that are still running). Legislation in California in the 1990s forced auto companies to revisit the idea, in order to reduce greenhouse gases, and now, despite an initial decade or two of legal action in lieu of innovation by the auto companies, the technology is finally turning up in showrooms.

Electric vehicles are about 90% efficient in their use of electricity, but if you live in a state that is largely coal-powered (Indiana, Wyoming, Kentucky) then the electricity itself is inefficiently produced. Coal-fired power from the utility is typically only 30% efficient.

Solar power on the roof is the best option for powering an electric car if you live in one of the eight states where solar panels are now cheaper than the utility with solar leases or power purchase agreements, with SunRun in California, Arizona, Colorado, New Jersey and Massachusetts, Solar City in Oregon, California and Texas, or Gro Solar in Pennsylvania and California.

Solar may not be that efficient either, but its wasted energy doesn’t cause climate change and there’s no peak sunshine for the next few billion years.

Image: Flikr user Roger Moore

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