Republican presidential nominee Donald Trump promised Monday to repeal a host of energy and environmental regulations, save the coal industry and lift restrictions on energy sales. But many of those promises may be challenging to fulfill. A new president cannot easily cancel most regulations, which require a lengthy, exacting process to enact or withdraw. More broadly, many of the coal industry’s woes are driven by world-wide market trends that are likely to persist regardless of the plans of any particular president. Mr. Trump, addressing a business-friendly audience at the Detroit Economic Club, painted a vision of a restored energy future. “We will put our coal miners and our steelworkers back to work, where they want to be,” Mr. Trump said. In an outline accompanying the speech, Mr. Trump cited several targets: Environmental Protection Agency rules that cut carbon emissions from power plants, known as the Clean Power Plan; the […]