PORTLAND, Maine (AP) — America remains awash in refuse as new cases of the coronavirus decline — and that has reignited a debate about the sustainability of burning more trash to create energy.

Waste-to-energy plants, which produce most of their power by incinerating trash, make up only about half a percent of the electricity generation in the U.S. But the plants have long aroused considerable opposition from environmentalists and local residents who decry the facilities as polluters, eyesores and generators of foul odor.

The industry has been in retreat mode in the U.S., with dozens of plants...