Analysis – Biomass carbon accounting debate heats up

While the U.K. government is
preparing sustainability criteria to be implemented later this year, the U.K.'s
Energy and Climate Change (ECC) committee is analyzing market-based evidence
provided by stakeholders in a meeting on May 21.

The Department of Energy and
Climate Change's (Decc) proposed sustainability criteria will use the current
carbon accounting tool based on methodologies set out in the EU's renewable
energy directive (RED), calculating emissions from harvesting, processing and
the transportation of biomass. As long as the calculations reach a minimum 60pc
reduction in carbon emissions versus coal, as well as meeting other criteria,
the fuel will be eligible for subsidies under the renewable obligation (RO)
scheme.

But several non-governmental
organizations say the methodologies used to calculate emissions fail to take
into account the emissions released on combustion, and indirect emissions from
diverting raw materials away from other industries or by leaving forests
standing.

"U.K. sustainability
proposals require a 60pc life-cycle reduction in carbon emissions of wood fuel
compared with other fossil fuels," says Harry Huyton, the RSPB's head of
climate change. "However, the calculation tool misses the impact of harvesting
wood on the carbon sink. Standing forests offset a huge amount of emissions."

But biomass market
participants on both sides of the Atlantic argue that calculating indirect
emissions as a result of diverting forest biomass away from other uses would be
entirely hypothetical and not representative of actual emissions.

"There is no way of telling
what would happen to the wood if it were not harvested for biomass energy," says
Todd Bush, U.S. producer Green Circle sales and marketing director. "And
unmanaged forests are at a far greater risk of forest fire and decay, which
will release the same amount of carbon but in a less managed way."

Bush noted that because of a
decline in forest products industries in recent years in the southeast U.S.,
raw material demand for any industries other than bioenergy is practically
non-existent, and therefore calculating indirect emissions for the U.S. southeast
would not reflect the situation.

"The only industry currently
putting a value on keeping our forests sustainably managed is biomass," Bush
said. "Without our industry, forests could be clear cut to make room for more
profitable uses of the land, which is almost exclusively owned by private
forest holders."

Carbon emissions from
biomass combustion in the boiler are neutralized because of the regrowth of
sustainably managed forests, according to biomass participants. Yet other
arguments against the current carbon accounting methodologies focus on the
length of time taken to repay that carbon debt.

But many of these arguments
focus on the absorption curve of a single tree being burnt for energy
consumption – while in managed forests, there will typically be stands of trees
of different ages which are harvested in sequence as they reach maturity,
according to biomass consumer Drax.

"Any assessment of carbon
stock has to look at the whole forest because for every mature tree that is
removed, there will be many others at different stages of growth," says Dorothy
Thompson, Drax chief executive. "Provided the overall rate at which carbon is
absorbed by the forest exceeds the rate at which it is being removed, there can
be no carbon debt."

"In the U.S. southeast we
are ramping up the amount of wood available for consumption, but we are still
only taking a fraction of the annual growth in carbon stock in the region,"
Bush added. "The net effect is a growth in carbon stock."

There is also evidence that
younger trees absorb more carbon, while trees closer to maturity absorb carbon
at a much slower rate, according to U.S. producer Enviva chairman John Keppler.

"To ensure we absorb the
maximum carbon from the atmosphere, we must sustainably manage our forests – cutting
down mature trees that are absorbing little carbon and replacing with young
trees," Keppler said at the Argus European Biomass Trading conference in April.

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