It’s a question getting asked a lot these days as the biomass industry grows and the U.S. tries to ween itself off of fossil fuels. Up until recently the answer has always been that biomass is a good alternative to burning coal and natural gas.

First a primer on what biomass is. It’s the burning of mainly waste wood to produce electricity. There are currently more than 80 biomass plants around the country generating half of all the renewable energy in the U.S.

The wood or fuel for the plants is mainly a by-product of logging. Trees are cut in the forest and their tops and limbs are taken off there where they fall. For centuries that waste has been piled up and burned in the forest.

But timber companies started to realize they could burn the wood and run their saw mills. The biomass industry was born. Now, instead of just running saw mills with the power, companies are feeding most of that electricity into the grid as green power. Utilities which are trying to increase their renewable portfolios have been buying as much biomass as they can.

But now the Environmental Protection Agency  has written a draft rule that would force biomass producers to measure the amount of carbon they release into the atmosphere same as coal and natural gas plants.

The argument is biomass produces a lot of CO2 and therefore it should not be considered carbon neutral. Trees that store carbon do so over an 80-year life span, but all that carbon is released in just minutes when burned.

The EPA says not all biomass plants are running as efficiently as they could and this would force the worse carbon polluters to clean up their act. But there is a big fear that if biomass loses its carbon neutral status the industry would quickly die. Investors would walk away from new projects and existing plants may even convert over to using natural gas going from an electricy producer to a consumer.

63 members of Congress are so worried about the impact they signed a letter to the EPA urging it to reconsider. They argue biomass is green, helps the health of our forests and provides jobs in many rural areas hit hard by a sharp decline in logging.