In April renewable energy exceeded the power made by coal plants. That is something new in the US and is part of a continuing change in the power industry.

Two big reasons: Coal has a tough time competing with renewable energy sources anymore. Spring and fall are times when coal plants may be offline for maintenance, so that could have played into the numbers.

Still, the renewable trend will continue. Take a look at the graph from the Energy Information Agency and see the way that coal has produced less electricity and renewables more over the last few years.

The Institute for Energy Economics and Financial Analysis said, “This represents a momentous development driven by the deep transition under way in the electric generation arena. It is also likely, particularly given IEEFA’s forecasts for continued declines in the amount of installed coal-fired capacity, and steady increases in the amount of installed solar and wind generation, that renewable output will begin outpacing coal more and more frequently.”

Coal power production is in blue. Renewables in red.

“How did we reach this point? asked Popular Mechanics, ” Well, part of the answer is timing. It’s springtime in the U.S, which means hydro power is peaking thanks to all the melting snow. At the same time, many coal plants around the country are shutting down for maintenance and upgrades. Renewables won’t outcompete coal all year round, at least not yet.

“But this record was also, in large part, because renewables have been getting cheaper and more powerful for years. Decades of innovation have gone into every wind turbine and solar panel in this country, and these energy sources have been getting exponentially cheaper.”