( By Carrington Dillon ) [Approx. Read Time: 1 minute]
Policy Analyst Drew Thornley posted this on National Review’s “Planet Gore” today. Feel free to comment and add to Drew’s critique the Environmental Leader’s shortcomings on their interpretation of the data. Thanks for the catch, Drew.
It Depends on What the Meaning of the Word ‘Exceed’ Is [Drew Thornley]
Today, in a piece entitled “U.S. Renewable Energy Exceeds Nuclear Power,” Environmental Leader writes, “According to the U.S. Energy Information Administration’s latest report, renewable energy accounted for 11.1 percent of U.S. production in April 2009, exceeding nuclear power.”
EL must be confusing capacity (i.e. energy-production potential) with generation (i.e. actual energy output). EIA data reveals that, in April 2009, nuclear power generated 59,129 thousand megawatthours of electricity (or 20.45 percent of the total electricity produced in April 2009), while hydropower and non-hydro renewables (like wind and solar) contributed 25,224 (8.73 percent) and 12,252 (4.24 percent) thousand megawatthours, respectively. Oh, and for the first 4 months of 2009, nuclear generated 263,755 thousand megawatthours (21.04 percent), while hydro and non-hydro renewables generated 87,799 (7 percent) and 46,038 (3.67 percent) thousand megawatthours, respectively.
You can subsidize costly capacity all you want, but, at the end of the day, capacity doesn’t keep the light on. Generation does. And, when it comes to actual electricity generation, much-maligned nuclear power is still miles ahead of renewables.
The WSJ has a good take on this as well. You’ve got to compare apples to apples
http://blogs.wsj.com/environmentalcapital/2009/07/30/have-renewables-really-eclipsed-nuclear-power/
Why would they run a renewable power source at anything less than full capacity? Is capacity the theoretical maximum amount of energy that could be produced under perfect conditions (say a wind turbine when it’s windy all the time) or is it a realistic estimate? The last question is mostly targeted towards power sources that are highly dependent on environmental conditions, like the aforementioned wind turbine.
Samuel,
You are on the right track. Capacity is the “advertised” capacity of a certain power source. Capacity factor is a ratio of the actual production of energy and the “advertised” production capacity. The reason wind (0.30) and solar (0.19) have such low capacity factors is because their fuel sources aren’t available all the time. You have to be careful when you see that, for example, a 100 MW solar plant is being built in Arizona, the plant will realistically only produce 0.19×100MW = 19 MW on average.
Nuclear power has an average capacity factor of a little over 0.90, with some utilities having averages as high as 0.94. The reason nuclear power plants don’t have a capacity factor of 1.00 is because they have planned “outages” in the spring and fall months in which power production is halted in order for routine maintenance to be performed on the plant. These outages last one to two months depending on the type of maintenance to be performed.
I usually don’t like to cite any Wikipedia entry, but the definition of capacity factor here is pretty good (http://en.wikipedia.org/wiki/Capacity_factor).
Thanks a lot for asking a question. I would have answered sooner, but I was out of town for the weekend. Feel free to come back and ask more questions in the future.
Take it easy,
Carrington