A comparison of Column D in Tables F.2 and F.4 shows a slight difference in their equivalence of cars and homes. Table F.2 shows that 1 million homes use as much energy as do 3.2 million cars, but Table F.4 shows that the same 1 million homes produce only as much CO2 as 2.5 million cars. This is because, per Btu, gasoline produces 4/3 as much CO2 as electricity or natural gas.
In the analysis above, energy (kWh), not power (kW or MW), is discussed. National newspapers often use “1 kW = 1 home” as the relevant conversion factor. This is nearly, but not quite, correct. A more realistic conversion is roughly 1.6 kW for an average California home, and roughly 2.4 kW for an average U.S. home. This is based on the assumption that an average California home uses approximately 8,000 kWh per year, whereas an average U.S. home uses 12,000 kWh. However, owing to fluctuations in power demand, a typical power plant runs for only about 5,000 hours per year rather than 8,760 hours per year.