BEIJING (AP) — Its efforts to cut pollution have made China the world leader in renewable energy development, yet that green power has been wasted as the country struggles to integrate wind and solar farms into an outdated and balkanized electricity network dominated by coal.

The problem threatens to slow China's progress in clearing its air and controlling the greenhouse gas emissions that make it the top contributor to climate change. It also could hamper any desire among Chinese leaders to fill the leadership gap left by President Donald Trump's move to withdraw the U.S. from the Paris clim...