You might say, for example, that "in 2008, the world total of electricity production was 20,279 terawatt-hours (TWh)." You need the time period however for it

You might say, for example, that "in 2008, the world total of electricity production was 20,279 terawatt-hours (TWh)." You need the time period however for it to make sense. Referring to a continuous generation capacity would be measured simply in terrawatts. As in "this number corresponds to an average rate of around 2.3 terawatts continuously during the year." The original article has an error as pointed out by the parent. Insert ironic mocking statement here.