Mass burn, or waste-to-energy facilities are on the decline in the U.S., and their troubles are largely about money and regulations. Shrinking access to renewable energy credits (RECs) and strengthening air quality standards that force expensive upgrades are testing operators working to stay in business. Between 2000 and April 2024, 51 trash incinerators in the U.S. closed permanently, leaving only 65 in operation as of April 2024, according to environmental advocacy group Energy Justice.