"Tech companies, like Google and Yahoo, use about 30 billion watts of electricity (1) - that's enough electricity to power 3 million houses for a year." Powerin

"Tech companies, like Google and Yahoo, use about 30 billion watts of electricity (1) - that's enough electricity to power 3 million houses for a year." Powering 3 million houses is a measure of power. Powering 3 million houses for a year is a measure of energy. 30GW, however, is a measure of power.