How much electricity does the U.S. use?

U.S. Energy Information Administration figures for 2008 said we used 3.8 trillion kWh / year.

So... what power is that in watts, and how many generating stations do we have/need?

A typical nuclear power plant (Beaver Valley) or coal fired plant puts out how much power?

[We found that this works out to about 380 1-GW plants. Typical coal plants that we found were smaller than 1-GW, so in very rough numbers ~1000 "big"-ish generating plants in any combination of coal and nuclear.]

How much electricity does a typical household use?

U.S. Energy Information Administration figures for 2008 said we used 3.8 trillion kWh / year.

This works out to about ~30 kWh per day, per person.

This means that one person uses 30 kWh of *energy* in the course of one day. But power is energy / time, so that means a typical American consumes an average power of:

$$P=\frac{E}{time} = \frac{30kWh}{24 h}=1.25 kW.$$

So, 100 people would need a power station generating 125 kW on average.

Households: 107 million households used 1140 billion kWh/yr

This is about 10 kWh per day, per person: our home usage. The rest is our share of industrial/hospital/school/etc use.

Solar power

Could solar power meet our household needs?

Generating solar energy

Typical family usage (Paul's!) ~$\frac{500 k W h}{m o n t h} \cdot \frac{1 m o n t h}{ 30 d a y s }$ ~17 kWh / day.

So, for 5 people, that's about 3-4 kW*hrs per day per person, the solar energy falling on 1 square meter of N. Indiana in an average day.

Current solar photovoltaic (PV) devices convert about 15% (~ 1/7) of the energy that falls on them into electricity. $=>$ we'd need about 7 square meters of solar panels per person.

Land use

Is 7 m${}^2$ / persons a ridiculous amount of land??

Compare this with the land area we as a society have dedicated to another public good: the interstate highway system. It's ~75,000 km long with an average density of 1000 km${}^2$ for every 800 km of length. That's an area of 94,000 square km. Dividing this by the current population of ~300 million, this works out to ~300 square meters of Interstate per person.

Daily variations

Both wind and solar are not *on* all the time, so some sort of supplementary storage is needed.

You can

• couple to hydroelectric dams, or
• pump water uphill (see Dinorwig)