The Trump administration hopes its plan will support rural communities that rely on coal industry jobs. ACE gives states more authority to set emissions reductions standards and claims it will promote investment in "clean coal." Like Obama's plan, ACE aims to cut carbon pollution from the power sector by around 30 percent from 2005 levels, but those emissions have already declined 28 percent since 2005.

The Obama administration's plan was stalled in court -- and Trump later signed an executive order to dismantle it. The Trump administration's plan could go into effect in 30 days, but it will likely face similar legal challenges before it's implemented. Already, New York State Attorney General Letitia James' office tweeted that it intends to sue the EPA over the plan, and The New York Times expects a "flurry of legal challenges."

Even if ACE can clear those legal hurdles, it's not clear if Trump's efforts will provide enough of a lifeline to keep the remaining coal-fired plants open. By the Sierra Club's count, 52 plants have either shut down or announced plans to shut down since Trump was elected. Most close because electricity from natural gas and renewable energy sources is less expensive to produce. Plus, philanthropists like Michael Bloomberg have committed millions to closing the remaining coal-fired power plants. So, even with a plan to keep wheezing coal facilities open longer, the Trump administration may not succeed.