In its scramble for new and clean energy sources, the U.S. government is failing to see the forest for the burning trees.

The burning of biomass to produce electricity is marketed as clean and renewable, and promoted by federal policies. But a report published Wednesday concludes that burning wood is more polluting than burning coal.

More than 70 wood-burning plants are under construction or have been built in the U.S. since 2005, with 75 more planned, according to the analysis by the nonprofit Partnership for Public Integrity.