Sunday, October 30, 2011

[biofuelwatch] Forest waste bioenergy usually worsens carbon emissions - study


Study says using forest waste for energy adds to carbon emissions
OSU scientists pivotal in research

By Steve Law

The Portland Tribune, Oct 24, 2011

A major effort to use forest waste to produce energy from West Coast forests would add to carbon dioxide emissions at least 14 percent, compared to current forest operations, according to a study published Sunday in the journal "Nature Climate Change." The study was conducted by scientists from the College of Forestry at Oregon State University and colleagues in France and Germany.

Researchers, supported by the U.S. Department of Energy, looked at 80 forest types and 19 bio-regions in Oregon, Washington and California, including public and private forest lands and different forest management practices.

"Most people assume that wood bioenergy will be carbon-neutral, because the forest re-grows and there's also the chance of protecting forests from carbon emissions due to wildfire," said Tara Hudiburg, a doctoral candidate at OSU and lead author of the study. "However, our research showed that the emissions from these activities proved to be more than the savings." 

The only exception, researchers said, was for forests in high fire-risk zones that become weakened by insects or drought, which impairs their growth and ability to sequester carbon.

"Until now there have been a lot of misconceptions about impacts of forest thinning, fire prevention and biofuels production as it relates to carbon emissions from forests," said Beverly Law, a professor in the OSU Department of Forest Ecosystems and Society, and co-author of the study. 

"If our ultimate goal is to reduce greenhouse gas emissions, producing bioenergy from forests will be counterproductive," Law said. "Some of these forest management practices may also have negative impacts on soils, biodiversity and habitat. These issues have not been thought out very fully."


Forest biofuel projects could increase West Coast carbon emissions

Forest thinningThinning West Coast forests on a widespread scale to feed bioenergy projects would increase the region's production of greenhouse gases, according to a new study.
Research published Oct. 23 in the journal  Nature Climate Change undermines the argument that substituting wood-based biofuel for fossil fuels would reduce carbon emissions.
"Most people assume that wood bioenergy will be carbon-neutral, because the forest re-grows and there's also the chance of protecting forests from carbon emissions due to wildfire," said Tara Hudiburg, the paper's lead author and an Oregon State University doctoral student in the College of Forestry. "However, our research showed that the emissions from these activities proved to be more than the savings."
Using data from thousands of forest plots in Oregon, Washington and California, Hudiburg and her co-authors calculated carbon storage and emissions under current forest management practices and then projected changes under three different thinning/biofuel scenarios.
Two involved thinning of varying intensity in fire-prone forests in the three states. The third called for widespread harvesting of trees up to 2 feet in diameter on public and private lands. The study assumed the harvested wood be burned to produce heat and power, converted to cellulosic ethanol and, in the case of larger, more valuable trees, milled into wood products.
The scientists took into account carbon dioxide emissions in harvesting, transportation and biofuel production as well as carbon credits for reducing wildfire and fossil fuel emissions, and long-term storage in lumber for housing. In some areas with relatively low forest productivity and high fire frequency, greenhouse gas emissions did not rise under the treatment scenarios. But in most they did.
"We are not saying that any project will increase emissions compared to current levels, whether they are from decomposition, wildfire, or harvest," Hudiburg said in an email. "We are saying that on average, this is what happens in West Coast forests, and if implemented widely will increase regional emissions -- contrary to policy goals." 
Total West Coast carbon emissions rose 2%, 6% or 14% under the three treatment schemes.
The study dealt solely with emissions and did not consider other potential benefits of forest thinning, such as reducing wildfire risk, which is projected to increase with global warming.
"In this study region," the authors wrote, carbon storage in forests "is more beneficial in contributing to reduction of anthropogenic carbon dioxide emissions than increasing harvest to substitute fossil fuels with bioenergy from forests."


Regional carbon dioxide implications of forest bioenergy production

Hudiburg et. al., Nature Climate Change, vol.1 pp.419–423, 2011 -- published
online 23rd October 2011

Strategies for reducing carbon dioxide emissions include substitution of
fossil fuel with bioenergy from forests1, where carbon emitted is expected to
be recaptured in the growth of new biomass to achieve zero net emissions2, and
forest thinning to reduce wildfire emissions3. Here, we use forest inventory
data to show that fire prevention measures and large-scale bioenergy harvest in
US West Coast forests lead to 2–14% (46–405 Tg C) higher emissions compared
with current management practices over the next 20 years. We studied 80 forest
types in 19 ecoregions, and found that the current carbon sink in 16 of these
ecoregions is sufficiently strong that it cannot be matched or exceeded through
substitution of fossil fuels by forest bioenergy. If the sink in these
ecoregions weakens below its current level by 30–60 g C m−2 yr−1 owing to
insect infestations, increased fire emissions or reduced primary production,
management schemes including bioenergy production may succeed in jointly
reducing fire risk and carbon emissions. In the remaining three ecoregions,
immediate implementation of fire prevention and biofuel policies may yield net
emission savings. Hence, forest policy should consider current forest carbon
balance, local forest conditions and ecosystem sustainability in establishing
how to decrease emissions.



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Biofuels are a wide range of fuels which are in some way derived from biomass.

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