When the US Dept. of Energy recently released the latest edition of its Annual Energy Review, that naturally included updated versions of their “flow diagrams”, which are still the most useful set of graphics I’ve seen for understanding the sources and uses of all energy, coal, petroleum, natural gas, and electricity in the US.
This time around, let’s do electricity:
(Click on the image above to see the full-size version in a new window.)
You can find links to all of the flow diagrams from the Annual Energy Review on the AER’s home page, in HTML and PDF format.
The things I find most interesting in this one include:
- The relative sizes of the sources. Coal really is about half, as much as we wish it were otherwise, and oil is a barely perceptible sliver (don’t tell the media; they still love their decades-old conviction that the US still generates a sizable portion of its electricity with oil). Renewables, while still smaller than we’d prefer, is mostly conventional hydroelectric power.
- Conversion losses practically leaps off the screen. This is (mostly) the energy lost in burning fuel to heat water to make steam to spin a turbine to pump electrons. When I show this chart to middle school students and tell them what “conversion losses” means, they give me the most withering, “Just how stupid are all you adults, anyway???” look. Aside from those awkward moments, it’s a good reminder that we decide things like how to generate electricity via economics, not energy or natural resource conservation.
- Transmission and distribution losses are tiny. The almost universal misunderstanding among mainstreamers is that T&D losses are a huge factor in their electricity costs, when it just isn’t so. By comparison, conversion losses are 24.8 times higher.
- The relatively even balance between residential, commercial, and industrial consumption. My guess is that while the commercial and industrial sectors are hardly paragons of environmental concern or even conservation purely for the sake of saving money, they’re probably on the whole much better than the residential sector. If my guess is right, then the low-hanging fruit for electricity conservation is in our homes and not at our jobs.
- Transportation’s share of consumption is so tiny you almost need a magnifying glass to see it. How much do you think that will change, on a percentage basis, in the next ten years?
Not bad for one diagram, eh?
July 7th, 2009 at 5:47 pm
I had no idea the conversion was so costly. I think I saw a similar image years ago and I assumed the conversion was the T&D.
Either way, many of the implications are the same. I.e., if you’ve got gas for cooking and/or heating, it’s better than electricity, both from the perspective of limited methane supplies and from the perspective of carbon liberation. (Unless you know that your local electricity provision is from something other than methane or coal.)
July 8th, 2009 at 5:06 pm
(I apologize for not approving your comment sooner. Today was straight out of bizarro world, so I managed not to see it until just now. I have this site configured to require the explicit approval of each person’s first post as a way to cull out the morons trying to sell boner pills, diet aids, and who knows what else.)
I think a lot of people make that same assumption (conversion is T and D).
I can’t prove it with numbers, but I think your conclusion about cooking is correct. In my case, we have a “green electricity option” among the gazillions of possible sources, so I get my electrons from wind and small hydro. I think it costs us something like 0.6 cents more per kWh, which is so ridiculously low that I don’t know how anyone could pass it up.