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WBA disputes forest biomass carbon payback, debt theories

By Erin Voegele | December 11, 2012

The World Bioenergy Association released a new biomass fact sheet at the United Nations Climate Change Conference (COP18) in December. The fact sheet, titled “The carbon neutrality of biomass from forest,” asserts that theories on carbon debt and “payback time” of biomass are not credible. According to the WBA, these assumptions are based on the unrealistic assumption that trees are burned before they are grown.

The fact sheet notes that replacing fossil fuels with sources of renewable energy must be the core strategy utilized within future climate policies. Utilizing biomass from sustainably managed forests can play an important role in this strategy,” said the WBA in the document. “Several countries have demonstrated that a buildup of carbon in forests and an increase of forest biomass for energy is simultaneously achievable by good forest management practice.”

While some organizations have argued that woody biomass should not be harvested in an effort to increase carbon dioxide storage, the WBA stresses that strategy isn’t feasible because forests stop growing as soon as their trees mature. In addition, the stored carbon in those mature forests will be released through decay, even if the biomass isn’t burned for energy.

In the fact sheet, the WBA outlines four stages of growth that each tree experiences, including planting and first establishment, growth, maturation and decay. According to the paper, each tree constantly absorbs carbon dioxide by photosynthesis and release carbon dioxide through respiration. “Until a tree progresses to its mature stage it is growing and absorbs more CO2 by assimilation than it releases by breathing,” said the association in the document. “In this phase the tree is a carbon sink. In the mature phase CO2 uptake and release are in equilibrium, the tree is carbon storage. As follows, during the decay phase, a tree will become a net carbon source.”

Rather than preventing the harvest of woody biomass, the association is urging governments to enforce sustainable forest management policies. According to the WBA, this can be accomplished through the use of sustainability criteria it has developed in combination with a biomass certification system.

A fully copy of the fact sheet can be downloaded from the WBA website.