Electronic – Kilowatt Hour Definition

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This is a very simple question but something that I'm not able to wrap my head around. This Energy report states generated electricity. But what does "generated killowatthours" mean? I know that can't mean that the US produced that much electricity every hour…but what exactly does it mean?

Best Answer

You are confusing kilowatt hours with kilowatts per hour (which is a fairly useless measure of anything).

A kilowatt is a measure of the rate at which energy is delivered (also known as power). One kilowatt means that 1000 joules of energy is being delivered every second.

A kilowatt hour is a measure of total energy delivered.

kilowatt      = energy/time

kilowatt hour = kilowatt x time
              = (energy/time) x time
              = energy

So if your water heater draws 6 kilowatts when it is on, and is on for 30 minutes, then it has consumed 3 kilowatt hours.

According to the report:

In 2011, the United States generated about 4,106 billion kilowatthours of electricity. About 68% of the electricity generated was from fossil fuel (coal, natural gas, and petroleum), with 42% attributed from coal.

kilowatt hours = 4,106,000,000,000 kWh

hours          = 356.25 days * 24 hours/day
               = 8766 hours

kilowatts      = (kilowatt hours) / hours
               = 4,106,000,000,000 kWh / 8766 hours
               = 468,400,639 kW

So we can see that during 2011, if you were to measure the power being generated in the USA, it would be about half a Terawatt.