Glossary
Capacity vs. consumption (MW vs. MWh)
Megawatts measure how much power can be supplied or drawn at a moment; megawatt-hours measure energy used over time.
Power and energy are different. Capacity, measured in watts (megawatts, MW, or gigawatts, GW), is the rate at which electricity can be delivered or drawn at any instant, like the width of a pipe. Consumption, measured in watt-hours (megawatt-hours, MWh, or terawatt-hours, TWh), is the total amount used over a period, like the water that flows through the pipe.
A 100 MW data center running flat out for a full year would use 876,000 MWh. In practice facilities do not always run at full load, and power plants do not always produce at full capacity, so the actual figures are lower.
Stories often quote capacity for data centers and power deals, and consumption for national or global electricity use. Comparing a megawatt figure with a megawatt-hour figure directly is a common error.
Read more: our explainer