According to recent postings on Cleantechnica.com, large wind turbines need to generate about 3kW to supply a home (a planned wind farm in KS has a capacity of 250MW and will satisfy the needs of 85,000 homes). A small rooftop turbine works out to 6 kW/home, due to the lesser efficiency of smaller blades. The small rooftop model seems terribly expensive ($6.70 per kW), so I'll stick with the 3 kW/home number.
They also state that the average home uses 670 kWh/mo, which is 70% higher than our usage (see yesterday). This means almost 800,000 homes could be served with a 1000 MW coal plant.
Tuesday, October 28, 2008
Monday, October 27, 2008
Electricity per month
We use about 400 kWh per month. A 1000 MW coal plant produces about 520 million kWh/per month (70% time on line, which amounts to about 1.3 million homes supplied if they are all like us). I expect (need to check) that our usage is below average and that the estimate that a 1000 MW coal plant can supply one million homes is not far off.
Saturday, October 25, 2008
Coal vs. Wind
I'm having a problem sorting out relative efficiencies of various electricity generation methods. For example, a 1000 MW coal plant is supposed to provide enough electricity for 1 million homes (this may be high, but I don't have good numbers). The power is then about 1kW/home. But only about 1/3 of the chemical energy of coal is converted to electricity.
Wind turbines need about 3 kW/home. So the efficiency of harnessing wind to produce electricity is in the same ball park as the efficiency for coal.
Wind turbines need about 3 kW/home. So the efficiency of harnessing wind to produce electricity is in the same ball park as the efficiency for coal.
Tuesday, October 7, 2008
More Solar Economics Data
There was a report in Sunday's Columbus Dispatch about a solar home with a claimed 10-12 year payback. The owner paid $41,500 and received State and Federal grants reducing that to $21,500. He has net metering.
In his best month, he generated 806 kWh, which provides 115,200 kWh over 12 years. At $0.10.kWh, this comes out to around $11,000 worth of electricity produced - I don't see how he can break even.
Refs:
"Solar power users amass savings by folllowing the sun", Columbus Dispatch, 08 Oct. 2008
Stowell web page:
In his best month, he generated 806 kWh, which provides 115,200 kWh over 12 years. At $0.10.kWh, this comes out to around $11,000 worth of electricity produced - I don't see how he can break even.
Refs:
"Solar power users amass savings by folllowing the sun", Columbus Dispatch, 08 Oct. 2008
Stowell web page:
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