One of the interesting side effects of plug-in electric cars turns out to be a greater awareness of energy sources and uses.

A 2012 California study, for instance, showed roughly four out of 10 electric-car drivers either had or were considering solar panels to provide electricity to their home.

And because electric cars everywhere in the U.S. have lower wells-to-wheels carbon-dioxide emissions than the average new vehicle, their ability to slow those emissions that contribute to climate change is huge.

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The climate-change argument, in fact, is one of the underlying topics electric-car owners find themselves discussing, given the politicization of that topic in the U.S.

So energy sources and uses have become more relevant to the discussion of future vehicles and their powertrains than many owners ever expected.

That's why we were so pleased to learn of the chart at the top of this article, produced by Lawrence Livermore National Laboratory using data and funding from the U.S. Department of Energy.

Global carbon dioxide emissions, 1850-2030 [CO2 Information Analysis Center, World Energy Outlook]

Global carbon dioxide emissions, 1850-2030 [CO2 Information Analysis Center, World Energy Outlook]

In one single graphic, it shows all the energy used in the United States.

It lists both where it comes from (solar, nuclear, wind, hydro, geothermal, biomass, natural gas, petroleum, and coal) and what it's used for (residential, commercial, industrial, and transportation).

And, you may note, the grey box at the top right contains a pretty grim kicker.

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Exactly two-thirds (66.4 percent) of the energy content from all those sources is wasted—or as the chart describes it, "rejected" into the atmosphere.

Just 30 percent actually provides those residential, commercial, industrial, and transportation uses. (The chart explains that totals may not add to 100 percent due to independent rounding.)

The waste is high in electricity generation (roughly two-thirds) and worst of all in transportation, where about four-fifths of all the petroleum used to power vehicles with internal combustion engines is wasted in heat and noise.

Chrome exhaust pipe

Chrome exhaust pipe

As the graphic notes, "End-use efficiency is estimated at 65 percent for the residential sector, 65 percent for the commercial sector, 21 percent for the transportation sector, and 49 percent for the industrial sector."

If you embiggen the graphic and look very closely, you'll see a tiny, thin orange line from the "Electricity Generation" box down to the "Transportation" use.

It represents the energy used by today's tiny number of electric vehicles in the U.S.

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According to all projections, that line will get thicker in the years and decades to come as adoption of plug-in vehicles grows both in the U.S. and globally.

Please let us know in the Comments, by the way, if you've seen studies on the relationship between home solar-power use and electric-car ownership. Thanks in advance.

[hat tip: Amanda Lavalle]


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