Global wind and solar developers took 40 years to install their first trillion watts of power generation capacity, and the next trillion may be finished within the next five years. That’s the conclusion of research by BloombergNEF, which estimated the industry reached the 1-terrawatt milestone sometime in the first half of the year. That’s almost as much generation capacity as the entire U.S. power fleet, although renewables work less often than traditional coal and nuclear plants and therefore yield less electricity over time.