A new study of southeastern forests in the U.S. finds that in the long run, burning wood instead of fossil fuels to make electricity can reduce heat-trapping carbon dioxide in the atmosphere, but not soon enough to prevent worsening the conditions leading to global climate change.
The study also shows that as the industry expands in the Southeast, biomass energy will increasingly come from cutting standing trees instead of using wood residues from sawmills and other sources, emphasizing the need to balance forest ecosystem health and related values, such as drinking water and wildlife habitat, with renewable energy objectives.
Based on current trends in using wood for large-scale power plants and exporting fuel pellets to Europe, biomass energy in the Southeast is projected to produce higher levels of atmospheric carbon for 35 to 50 years compared to fossil fuels. After that, biomass will result in significantly lower atmospheric levels as regrowing forests absorb carbon from previous combustion.
The study, Biomass Supply and Carbon Accounting for Southeastern Forests, was conducted by the Biomass Energy Resource Center in partnership with the Forest Guild and Spatial Informatics Group on behalf of the National Wildlife Federation and the Southern Environmental Law Center, and was funded by a grant from the Doris Duke Charitable Foundation.
The study analyzed 17 existing and 22 proposed biomass facilities in seven states—Alabama, Florida, Georgia, North Carolina, South Carolina, Tennessee and Virginia. Researchers developed a new analytical framework that integrates life-cycle carbon accounting with forest growth and management, as well as supply zone (or "landscape woodshed") data specific to the region. The results are specific to biomass electric power in the Southeast, and different regions and technologies will have different effects on atmospheric carbon.
"This study brings us to the crux of the matter regarding biomass electric power and atmospheric carbon, which is that consideration of near-term tipping points versus long-term carbon reductions must be assessed as we develop climate and energy policy," said Andrea Colnes, policy director for the Biomass Energy Resource Center. "For example, using wood to produce heat through clean technologies has a much shorter payback period than producing electric power, and can yield climate benefits in five to ten years."
"While biomass offers some environmental benefits, any expanded use of logging residue and live trees will affect forest structure and nutrient cycling," said Robert Perschel, eastern forests director with Forest Guild. "This raises questions of long-term forest health and other environmental factors, such as water quality and wildlife habitat, that need to be addressed by further study and reasonable guidelines for the industry."
The Southeast is seeing rapid growth in new and retrofitted power plants that will burn woody biomass to make electricity, as well as a major expansion of the wood-pellet industry, largely for export to Europe. The short-term spike followed by the long-term drop of carbon levels from these facilities poses challenging questions for decision makers in addressing both energy and climate change policy, particularly when factoring in a projected climate change "tipping point."
If carbon emissions continue unabated for the next three to five decades, the planet will likely warm an average of 3.8 degree Fahrenheit, a threshold that scientists and the international community have identified as resulting in irreversible interference with the climate system. This could have significant impacts; for example, the destructive power of hurricanes and severity of droughts could increase, and up to one-third of the world's species could face extinction.
"The timing problem is central to this issue, since adding even more carbon from biomass to the atmosphere over the next 35 to 50 years could accelerate global warming stressors," said Julie Sibbing, director of agriculture and forestry with National Wildlife Federation. "We run the compounded risk of losing forests to severe weather events triggered by climate change, such as droughts and flooding, undermining their ability to sequester carbon over the long run."
"Just because wood is a renewable resource doesn't mean it's automatically carbon neutral," said David Carr, senior attorney at the Southern Environmental Law Center. "How biomass is obtained, burned, and regrown determines its carbon footprint and impact on forest health. To do this right, EPA must require a 'forest-to-furnace' accounting of the biomass carbon cycle to ensure it doesn't hasten climate change."
The choice of combustion technology matters greatly in the carbon footprint of biomass. Previous studies have shown that burning biomass for thermal energy is 70 percent to 80 percent efficient, as opposed to electricity generation which is just 25 percent efficient. Also, the BERC study shows that most of the wood pellets produced in the Southeast are shipped to Europe. The EU assumes that all biomass burned for power is carbon neutral, providing extra incentive for the use of wood pellets from the Southeast. "The EU, like EPA, must require a full carbon accounting that identifies and discourages biomass that worsens global climate change," Carr said.
Overall, the study's results point to the need for state and federal policies to incentivize efficient uses of woody biomass that maximize the benefits and minimize the near-term spike in atmospheric carbon.
A map of existing and proposed biomass facilities in the Southeast is available by clicking here.
For more information, click here.
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Research carried out at the Catlin Arctic Survey’s Ice Base in March and April 2010 suggests that melting sea ice is weakening the Arctic Ocean’s ability to capture and store atmospheric carbon.
This study, carried out by a team at the Department of Fisheries and Oceans, Canada, focuses on the efficiency of an important biological ‘pump’ that captures atmospheric carbon near the sea surface and then draws it down and stores it on the sea floor.
Phytoplankton (plant plankton), near the sea surface, capture atmospheric carbon and store it as non-sinking microscopic particles. Although these particles do not themselves sink, their sticky nature means they can capture heavier organic debris and become sufficiently dense that they fall to the ocean floor as ‘marine snow’, effectively removing significant amounts of atmospheric CO2 to the deep ocean for thousands of years.
The findings also show that carbon-rich gel-like particles (so-called transparent exopolymer particles, or TEPs) are stored in the sea ice during winter and are released into the water column during early spring. TEPs are an important feature in the carbon cycle as they both capture carbon and give marine snow its stickiness, enabling it to attract organic debris and sink.
Future increases in surface freshwater from melting sea-ice will likely strengthen water layering and could change carbon draw-down in the Arctic Ocean. Coupled with the continuing retreat of sea ice, this has implications for the capacity of the Arctic Ocean to mitigate increasing atmospheric CO2 emissions via carbon capture.
The oceans represent the largest active carbon sink on Earth, absorbing more than a quarter of the CO2 that humans put into the air. According to a recent estimate, the Arctic is responsible for 5 to 14 percent of the world’s CO2 uptake, although it accounts for only 3 percent of its ocean surface area.
Dr. Oliver Wurl, who carried out this research, was part of an international team of scientists who lived and worked at the Catlin Ice Base on the Arctic Ocean during the brutally cold winter-spring transition as part of the Catlin Arctic Survey 2010 expedition.
"The data was really hard-won," said Dr. Wurl. "Collecting sea water samples in minus-40ºC is not something I would recommend to anyone, but to see this data forming part of an important jigsaw puzzle makes all the hardship worthwhile.”
The paper is published in the Journal of Geophysical Research.
For more information, click here.
The Catlin Arctic Survey, sponsored by global specialty insurer and reinsurer Catlin Group Limited involves an ‘Ice Base’ and an ‘Explorer Team’.
The Ice Base is a unique, purpose-built field research station, located on floating sea ice in the Canadian Arctic archipelago (78°45’N, 103°30’W). This Winter/Spring Ice Base played host to an international team of research scientists from the UK, U.S. and Canada in both 2010 and 2011.
The Explorer Team, in 2010, comprised Charlie Paton, Martin Hartley and Ann Daniels. The team undertook a long-range survey, traveling across the Arctic’s sea ice, collecting water samples to provide data on ocean acidification. Explorer Teams also participated in the 2009 and 2011 Catlin Arctic Surveys.