Whenever power plants are proposed, the accompanying statement generally says, “will power h houses” and “will reduce GHG emissions as much as taking c cars off the road”. Today, we’ll look at the first claim.
Most articles assume that each house uses electricity at the rate of 1 kW, that is, every 24 hours a house uses 24 kWh, every year, a house uses 8760 kWh. How accurate is this? For California, it’s a good assumption.
I’ll choose two other states to check, though, Ohio and Texas, arbitrary choices.
In Texas in 2001, the average person used 5,600 kWh in the home. In Ohio, it was 4,200 kWh. Today’s per capita use is likely at least as high.
TX: 5,600 kWh/year * 1 year/8,760 hours = 0.64 kW
OH: 4,200 kWh/year * 1 year/8,760 hours = 0.5 kW
The average American uses electricity somewhere between 0.4 kW and 0.7 kW. Look at your daily use on your bill, and divide by 24 hours to get the rate of use for your house.
The average Texas household has 2.74 people. The average Ohio household has 2.49 people.
TX: 0.64 kW/person * 2.74 people/house = 1.75 kW/house
OH: 0.50 kW/person * 2.49 people/house = 1.24 kW/house
So a power plant would need to average 1.75 GW in Texas, 1.24 GW in Ohio, to power 1 million households.
The capacity factor tells us how much electricity a power plant produces, compared to its rated capacity. A nuclear power plant, with a 90% capacity factor, produces only 90% as much electricity. The average US windmill currently produces only 27% as much, though this varies regionally and is presumably increasing. The average German windmill only produces 20% of its rated capacity.
If a power plant is built outside California, or other low-electricity states like Hawaii, don’t assume that the 1 kW/house rule holds.
Want a pictoral representation of how your state compares?
Karen it is hot in Texas. We are going to run out air conditioners every day between May first, and September 30th. And there may be uncomfortably warm days in December. Wind generated electricity is too unreliable to be counted on for base power. On the hottest summer days, when electrical demand for air conditioning is at its peak, the wind just does not blow iin Texas. Period, end of story. Since coal is no longer viable here for new power plants, we need new nuclear generators, or folks are going to start to die, on hot Texas summer days.