The Massachusetts Department of Energy Resources released a new set of strict standards for biomass in early May that have the potential to cut subsidies for developing plants. According to these new requirements, all qualifying biomass plants must generate power at 50 percent efficiency to qualify for one-half Renewable Energy credit (REC) per MWh, and 60 percent for one full REC. These new standards are up from the previous 25 percent efficiency requirements. Plants will also be required to analyze lifecycle emissions to demonstrate at least 50 percent reductions over 20 years.
These decisions were largely influenced by the oft-debated 2010 Manomet Center for Conversion Sciences study, which determined that biomass electricity is not carbon neutral and not effective for cutting greenhouse gas emissions. According to Manomet, biomass plants release more CO2 for every kilowatt of energy produced than most fossil fuel. Essentially, we would be removing trees that “catch” carbon from entering the atmosphere, and burning them creates an even larger CO2 imbalance or “debt.”
These findings have been heavily debated. Dr. William Strauss of FutureMetrics issued a retort, “How Manomet Got it Backwards,” in which he explains that the Manomet argument is based on a debt-then-dividend assumption, where a debt is incurred when CO2 is released from burning trees and then repaid as trees gather carbon during a growth cycle. “The Manomet study’s logic essentially begins with a full grown tree, then that tree is harvested and used for energy while its stored carbon is released as CO2 (the debt), and then they continue to watch the empty spot where the tree was for 30 to 50 years while a new tree grows in its place. Only after that regrowth is the carbon debt repaid (the dividend).”
Strauss argues that Manomet makes too many assumptions – rather than assume every tree will be harvested, he believes that the carbon released from selective harvesting is offset by carbon accumulation from the entire systems’ growth. From his research:
“If there is a forest system with 1,000,000 tons of biomass on January 1 of a given year, and that system has 1,010,000 tons of biomass on December 31 of that same year, then the forest has increased its carbon stock over the year and it is embodied in the extra 10,000 tons of biomass. If 10,000 tons are harvested from the system on December 31, then the system begins the next year with the stock of biomass and carbon at the same level that it was at the beginning of the previous year.”
Others have argued that the Manomet study failed to account for the use of waste wood. This method allows biomass plants to burn dead, rotting material from the forest floor. Waste wood removal is believed to promote new forest growth and leads to increased carbon absorption, which goes above and beyond carbon-neutrality.
Despite these arguments, Massachusetts has set the bar high, and many fear that these limitations will influence the upcoming EPA (Environmental Protection Agency) decision regarding biomass boiler MACT (Maximum Achievable Control Technology) regulations.
Said Bob Cleaves, president and CEO of the Biomass Power Association, “If the Massachusetts policy were applied nationally, almost 50 percent of the Nation's renewable energy — the portion supplied by biomass — would be considered non-renewable. Without policy support, new plants wouldn't be built, and existing facilities would close. The result would be less investment in forests, which would mean less carbon being absorbed, more land use conversions, and more carbon in the atmosphere.”
Image: Kuzma via Shutterstock
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