Renewable energy now generates more electricity in the United States than coal. Solar, wind, hydropower, biomass, and geothermal totaled 21.56 percent of U.S. generating capacity as of April, according to a report from the Federal Energy Regulatory Commission (FERC). Coal, meanwhile, accounted for just 21.55 percent of capacity, down from 23.04 percent last year.

As Engadget reports, this gap is likely to widen in the coming months. FERC notes that renewable energy has added 1 percentage point to its share of U.S. installed capacity every year, and says that sector could account for 25 percent by 2022. A total of 186,000 megawatts of proposed wind and solar projects are expected to go online in the next four years.

Coal capacity has dropped to its lowest level in 40 years. According to the U.S. Energy Information Administration, more than half of the U.S. coal mines operating in 2008 — when coal production peaked — have since closed. Natural gas, however, continues to grow, accounting for more than 44 percent of U.S. total energy capacity in April.