Sources and Uses of Electric Power Consumed in the United States

Michael Giberson

From the Annual Energy Review by the Energy Information Administration (a unit of the U.S. Department of Energy), a chart showing the sources and uses of electric power:

EIA chart: Electricity Flow,  2008
EIA chart: Electricity Flow, 2008

Via Lou Grinzo at the Energy Collective. Click through on the chart to see a larger version (or get the PDF) from EIA.

The chart is too aggregated to do detailed analysis, but good for some “big picture” looking. Grinzo offers a few comments,  here are two of his remarks that seemed particularly worthy of note: “Conversion losses practically leaps off the screen,” and “Transmission and distribution losses are tiny.” As Grinzo suggests, the conventional view usually gets it backward: mostly ignoring conversion losses and often exaggerating the relevance of line losses. (See Grinzo’s post for the rest of his commentary.)

Cogeneration offers some efficiency benefits by reducing the energy wasted both in conversion and in line losses, but you can’t see that on the chart.  I was surprised to see, in another table in the Annual Energy Review, that the “useful themal output” from combined heat-and-power plants (cogeneration plants) has been falling beginning about 2001. I guess I haven’t been paying attention. Is this due to the expiration of PURPA contracts? Something else? I don’t know.

Here is another chart from the EIA, this showing primary energy consumption by sector (again, click through to the source chart at the EIA for a larger version):

EIA chart: U.S. Primary Energy Consumption by Source and Sector, 2008
EIA chart: U.S. Primary Energy Consumption by Source and Sector, 2008

7 thoughts on “Sources and Uses of Electric Power Consumed in the United States

  1. David Z:

    It’s the energy lost to the environment from either burning the fuel or cooling the steam returning to the boiler. You know when someone says a plant is 37% or 50% efficient? That percentage refers to the share of input energy that gets converted to useful output energy.

    I know the numbers look bad, but if it’s any consolation, power plants tend to have higher conversion efficiencies than internal combustion engines.

  2. Interesting question on the useful thermal output. I’m associated with Recycled Energy Development, which does combined heat & power and waste energy recovery. I don’t know the answer but will look into it. In the meantime, I’ll just say I think CHP/cogeneration is really the best way to reduce those conversion losses. The principals of our company generally make power generators that are about 80% efficient. The worst one they’ve ever done was 70%, and the very best topped 90% (though that’s rare). Beyond the number-crunching, though, lies the heart of the matter: we cannot begin to solve the global warming problem until we vastly improve our energy efficiency. That’s the elephant in the room.

  3. Great information–you must read some terrific sites. (Just kidding.)

    I posted this originally on my site (The Cost of Energy) because I thought it was a great example of how much pertinent information, sometimes with distinct policy implications, you can find in a single chart.

    I agree with miggsathon’s comment about efficiency. We have to get much more serious about the efficiency of virtually every use of non-renewable energy resources if we’re to avoid some truly nightmarish problems. As I so often say on TCOE: The future will be a lot of things, but “dull” isn’t on the list.

  4. A problem with these charts is that the fossil fuels are measured by their heat values and nuclear and renewables are measured by their electric outputs. The second chart in particular suffers from this comparison. Electric should occupy a slot in its middle.

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