Special Report No. 04-03: An Analysis of the Methods Used to Address the Carbon Cycle in Wood and Paper Product LCA Studies
An extensive worldwide literature search was conducted to find Life Cycle Inventory (LCI) and Life Cycle Assessment (LCA) studies that considered the carbon cycle for wood or paper products in the use and end of life stages. The principal issues of interest were how the fate of carbon was evaluated during the product use phase and end of life in landfills, including methane emissions from landfills.
Sixty-six LCAs have been identified on wood and paper products. Most of these do not address carbon flow issues throughout the entire life cycle but focus instead on other environmental parameters usually included in life cycle studies. Where biomass carbon is addressed, it is usually only in the context of carbon taken from the atmosphere and fixed into trees. Carbon sequestered in products and methane emissions from landfills are ignored in most studies, although many more studies address methane emissions than address carbon sequestration in products and landfills. Where biomass carbon is included it is usually, but not always, considered global warming neutral.
Of the 66 LCA studies, 13 were selected for in-depth review. Many of these presented clear statements on how product use and end-of-life carbon storage and carbon dioxide and methane releases were handled, but most of these lacked good data support. Many of the authors used very simple assumptions and cited the lack of good data or methodology. Typical assumptions for landfills were that all organic products decay in landfills, no organic products decay in landfills, or some fraction decays in landfills. There was little uniformity in assumptions on methane emissions and recovery, with only studies for the United States Environmental Protection Agency (EPA) and a German company; citing actual measurements.