747's or ReservoirsLetter from Reed Burkholder
November 19, 2001
I have been thinking a lot about the low electrical output of hydropower dams as compared to the high output of jet aircraft engines (gas turbines).
Lower Granite Dam passes through its turbines all the flow from the Snake River, the Salmon River, the Clearwater River, the Imnaha River, and the Grande Ronde River - in other words every drop that passes out of southern Idaho, central Idaho and northeastern Oregon.
Would we expect that the electrical generation at this dam to be high? After all, that's a lot of water and the drainage is millions and millions of acres.
During September, October and November of this year Lower Granite has been behaving like a smallish sort of power plant. At the low end, it has generated about 83 megawatts (September 20, when the flow averaged 11,300 cfs) and at the high end it has generated 185 megawatts (November 2, when flow was 25,800 cfs).
Every morning at about 6:00 AM I hear the Boeing 737's taking off from the Boise Airport. Each engine, when used as a power plant, can generate 25 megawatts. Each Boeing 737 that I hear is the equivalent of a 50-megawatt power plant that is so light and compact that it can fly.
Hydropower, I suspect, looked pretty powerful back in 1930 when there were no modern gas turbines, coal-fired generators, diesel engines, or high-tech wind generators. But I think hydropower is hard to justify anymore, particularly on rivers where salmmon runs are endangered.
Here's a second example of the low output of hydropower. The electrical generators at McNary Dam use the entire flow of the Columbia River. This includes all the water from Canada flowing into the Columbia, the water from western Montana, the water from eastern Washington, northeast Oregon, and all of Idaho (except the little bit that flows into Salt Lake from the Bear River). Between November 1 and November 12 of this year McNary has averaged 470 megawatts (its powerhouse has a capacity of 980 megawatts).
Boeing 747 engines are also used as power plants. Whan all four are used as combined-cycle combustion turbines they will generate 220 megawatts. Thus the entire November flow of the Columbia passing through McNary's turbines is the equivalent of a little more than the output of two Boeing 747 jet aircraft.
There' new hope for our salmon runs. Up with river-saving technologies. Down with hydropower!
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