Wei et al. Carbon Balance and Management
(2023) 18:1
Page 6 of 10
product (in kg C per year) including non-energy use biochar, building, exterior use, home application, and paper carbon pools. The input wood product data includes products made from harvested timber and recyclable waste wood materials when the system boundary includes the products made from recycled waste wood materials. Parameters including the com- bustion efficiency of biofuel, charcoal decay rate, dis- posal rate for each end-use wood product, recycling rate for each recyclable wood product, and decay rate for each type of waste wood material in landfills can be manually calibrated by users (To perform an estima- tion, see Additional file 1). Estimator application The WPsCS Estimator was applied to estimate the car- bon stored in wood products produced by timber har- vested in Maine, USA, over the period of 1961–2019. For this estimation, the production system boundary was employed, meaning that all carbon in wood products har- vested in Maine was accounted for regardless of whether it was used in Maine or elsewhere. The timber harvesting data were obtained from the Maine Department of Agri- culture Conservation and Forestry (Fig. 3a). To obtain the production of each type of wood products, the allocation method proposed by Li et al. [20] was used. Because this allocation method does not categorize the paper prod- ucts, the annual fraction of newspaper, graphic paper, packing paper, and household paper of the entire United States provided by the FAOSTAT database [29] was used to allocate paper products. For a second demonstrative application, the estima- tor was applied to calculate the carbon storage in wood products consumed in the United States. For this estima- tion, we used the stock-change system boundary, which estimates the carbon stock in wood products consumed and physically located in the United States, while the wood products exported internationally are not counted. The annual domestic product, as well as the import and export of biofuel, non-energy use biochar, sawlog, struc- tured panel, non-structural panel, paperboard, and paper products in the United States during the period of 1961 to 2020 were obtained from the FAOSTAT database [29]. Therefore, the consumption of each wood product in the United States was calculated as the total of the commer- cial balance (the difference between import and export) and domestic product (Eq. 6). To allocate these second wood products including sawlog, structured panel, non- structured panel, and paperboard to end-used wood products (Fig. 3b), we applied the consumed solid wood timber products in major end-use markets data in the United States provided by McKeever and Howard [30] and Alderman [31].
Fig. 3 The annual production of wood products made from the timber harvested in Maine, USA during the period of 1961–2019 ( a ), and the annual consumption of wood products in the United States from 1961 to 2020 ( b )
(6)
W c = ( W i − W e ) + W product
where W c is the annual consumption of a wood product in the United States, W i is the imported wood product, W e is the exported wood product, and W p is the domestic wood product produced in the United States. Estimator parameterization Parameters for the WPsCS Estimator can be obtained from expert knowledge and industry surveys or life cycle inventories, but the use of parameters from previous studies is a common practice [32, 33]. To realize the two estimations demonstrated here, we developed a set of parameters including the combustion efficiency, charcoal decay rate, disposal rates for end-use wood products, recycling rates for recyclable disposed wood materials, and decay rates for waste wood products in landfills. The combustion efficiency was obtained from published stud- ies [34–37] and it is an average value for both industrial fuel and residential fuel (Table 1). The charcoal loss rate
Made with FlippingBook flipbook maker