While a megawatt measures the power or capacity of an electric system, a megawatt-hour represents how much electricity is delivered through that system in an hour. For example, if a 1 megawatt solar array runs in the full sun for an hour, it will theoretically produce 1 megawatt-hour of electricity.
Most people are used to seeing electricity measured in kilowatt-hours on their electric bills. A megawatt hour is simply 1000 kilowatt-hours. Other common measurements are gigawatt-hours (1000 megawatt-hours), terawatt-hours (1000 gigawatt-hours), and petawatt-hours (1000 terawatt-hours). To put these massive numbers in perspective, the US uses a bit over 4 petawatt-hours of electricity each year, while the sun delivers around 192,000 petawatt-hours to the Earth’s seven continents each year.
Making a megawatt-hour
So what resources are needed to produce a megawatt-hour of electricity? It takes approximately:
- 1,100 pounds of coal 
- 7,600 cubic feet of natural gas 
- 1/20th of a solar panel over its lifetime 
- A wind turbine spinning for 30 minutes 
- 1.5 million gallons of water flowing over a hydro dam 
- 79 pounds of uranium ore and 0.1 ounce of enriched uranium 
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- The US Energy Information Administration (EIA) has tons of information on coal, like their coal home page and lots of cost data on coal.
- The EIA also has a home page on all-things-nuclear here.
- To see all the sources used in this analysis, as well as the math, tying it together, you can download the spreadsheet and take it for a ride yourself.
- Math; It takes 1.1 pounds of coal to make a kilowatt-hour of electricity, Freeing Energy
- Unit – Megawatt Hour Sources (mhws).xlsx, tabs mwhs.3, mwhs.4, Freeing Energy
- Unit – Megawatt Hour Sources (mhws).xlsx, tab mwhs.5 Freeing Energy
- Unit – Megawatt Hour Sources (mhws).xlsx, tab mwhs.6, Freeing Energy
- Unit – Megawatt Hour Sources (mhws).xlsx, tab mwhs.7 Freeing Energy
- cost – nuclear (nu).xls, tabs nu.3, nu.4, nu.5, nu.6 Freeing Energy