About 90% of Maine is forested, the highest percentage wooded area of any state. With cold winters and an ample supply of trees, burning wood to heat homes is an age-old practice in Maine.
Currently, about one in ten Maine households uses wood as the primary heating fuel. Also, Maine generates electricity by burning biomass (wood and wood waste-derived fuels, such as wood pellets). According to the U.S. Energy Information Agency, biomass fueled one-fourth of electricity generation in Maine over the past 20 years, the largest percentage in any state. In fact, Maine consumes more energy from burning biomass than from any other energy source, including heating oil and motor gasoline.
In sum, biomass is a really big deal in Maine and, yes, even though it is considered renewable, burning biomass pollutes. It may be time to rethink our love affair with renewable energy from biomass and shift to cleaner renewable energy.
Maine is ranked among the states as a top producer of renewable energy. In 2019, Maine boasted an impressive 80% of electricity from renewable sources with major contributions from hydropower (~30%), biomass generation (~25%), and wind (~25%). But there is one important difference between biomass as a renewable resource compared to the others: similar to burning a fossil fuel, biomass burning emits significant greenhouse gases. In fact, burning wood actually produces more greenhouse gases in the short term compared to burning natural gas and oil. Also, if a tree is harvested and not replanted, it’s a triple whammy: not only will it emit considerable greenhouse gases when burned, but its loss contributes to deforestation and eliminates its capacity to sequester carbon.
The term “carbon neutral” means carbon emissions are balanced by carbon savings from other energy sources. In the United States, according to EPA policy, biomass is a renewable (carbon neutral) energy source, provided “the use of forest biomass for energy production does not cause conversion of forests to non-forest use.” This is simply a best-case scenario; numerous studies have concluded that if trees are replanted at all, it takes 50 to 100 years to reach carbon neutrality.
Fortunately, there is a move underway to reconsider this shortsighted position. In May 2020, more than 200 U.S. environmental scientists sent a letter to Congress urging lawmakers to reject the rules that define biomass, when burned to produce energy, as being carbon neutral.
In the short term, burning biomass is more harmful than burning fossil fuels. When wood is used as a home heating source, the wood burned emits more carbon up smokestacks than heating with oil or natural gas. In fact, for each BTU of heat, using wood is likely to add two to three times as much carbon to the air as using fossil fuels.
Whether used for heat or electricity generation, the idea that burning biomass is carbon neutral is simply not the case in the near term. The harvested trees may not grow back, land may be repurposed for other uses, and insect damage, disease, and extreme weather may limit regrowth. Even if forests eventually remove the previously emitted carbon, the extra carbon released into the atmosphere will accelerate global warming.
Biomass as a “carbon neutral” renewable energy source certainly is a nuanced topic, and its use has been under debate for decades. Recently enacted Maine law requires the state “to include both gross emissions from all sources, including from the combustion of biomass, as well as a carbon sequestration estimate, in the biennial greenhouse gas report submitted to the Legislature, starting in January 2022.”
Submitting a report next year, however, does not solve an urgent problem. We must immediately stop treating biomass as a carbon neutral energy source and switch to clean renewable heating (air source or geothermal heat pumps) and truly renewable electricity that is generated from hydro, wind, or solar sources.
To meet our emission goals, and preserve our planet for future generations, we need to preserve and restore forests — not burn them.
York Ready for 100% is a grassroots citizens’ organization dedicated to building sustainability and reducing the causes of climate change and its effects on humans and the natural world. For more information see yorkreadyfor100.org or info@yorkreadyfor 100.org. Information and sign-up for York EcoHOMES can be found at the same site.