SHARM EL SHEIKH, Egypt — Michael Bloomberg, the former mayor of New York City and now a special envoy on climate change for the United Nations, announced a new international plan on Monday to help 25 countries in Africa, Asia and Latin America phase out coal by 2040.“We’ve seen that it’s possible to expand access to clean, affordable energy and cut carbon emissions at the same time,” Mr. Bloomberg said in a statement, noting that in the United States more than two-thirds of coal plants have shuttered thanks to a mix of activism that has prompted Democratic administrations to impose regulations, and market forces that have made coal far more expensive than gas or solar.Mr. Bloomberg said that for developing countries, policy analysis and technical assistance were “the side of energy development that doesn’t get a lot of attention but can mean the difference between investment in coal and clean power.”Indonesia, for example, is the third-largest coal producer after China and India, and its energy plan foresees coal providing a quarter of its power mix by 2050.Meanwhile, many nations in Africa have enormous wind and solar resources but because of perceived risks, financing costs can be higher.The coalition of governments includes Bangladesh, Botswana, Brazil, Cambodia, Colombia, the Democratic Republic of Congo, Egypt, Ethiopia, Ghana, Kenya, Madagascar, Mexico, Morocco, Mozambique, Nigeria, Pakistan, Philippines, Rwanda, Senegal, South Africa, Tanzania, Thailand, Turkey, Uganda and Vietnam."