Does replacing coal with wood lower CO[subscript 2] emissions? Dynamic lifecycle analysis of wood bioenergy
Name
Sterman_2018_Environ._Res._Lett._13_015007.pdf
Size
1.72 MB
Format
Adobe PDF
Checksum (MD5)
2953ebb0dcb9f8a8a3c6a267e204dfc0
Author(s)
Siegel, Lori
Rooney-Varga, Juliette N
Sterman, John
Date Issued
January 2018
Journal
Environmental Research Letters
Publisher
IOP Publishing
Citation
Sterman, John D., et al. “Does Replacing Coal with Wood Lower CO[subscript 2] Emissions? Dynamic Lifecycle Analysis of Wood Bioenergy.” Environmental Research Letters, vol. 13, no. 1, Jan. 2018, p. 015007. © 2018 The Authors
Version
Final published version
Abstract
Bioenergy is booming as nations seek to cut their greenhouse gas emissions. The European Union declared biofuels to be carbon-neutral, triggering a surge in wood use. But do biofuels actually reduce emissions? A molecule of CO[subscript 2] emitted today has the same impact on radiative forcing whether it comes from coal or biomass. Biofuels can only reduce atmospheric CO[subscript 2] over time through post-harvest increases in net primary production (NPP). The climate impact of biofuels therefore depends on CO[subscript 2] emissions from combustion of biofuels versus fossil fuels, the fate of the harvested land and dynamics of NPP. Here we develop a model for dynamic bioenergy lifecycle analysis. The model tracks carbon stocks and fluxes among the atmosphere, biomass, and soils, is extensible to multiple land types and regions, and runs in ≈1s, enabling rapid, interactive policy design and sensitivity testing. We simulate substitution of wood for coal in power generation, estimating the parameters governing NPP and other fluxes using data for forests in the eastern US and using published estimates for supply chain emissions. Because combustion and processing efficiencies for wood are less than coal, the immediate impact of substituting wood for coal is an increase in atmospheric CO[subscript 2] relative to coal. The payback time for this carbon debt ranges from 44-104 years after clearcut, depending on forest type- A ssuming the land remains forest. Surprisingly, replanting hardwood forests with fast-growing pine plantations raises the CO[subscript 2] impact of wood because the equilibrium carbon density of plantations is lower than natural forests. Further, projected growth in wood harvest for bioenergy would increase atmospheric CO[subscript 2] for at least a century because new carbon debt continuously exceeds NPP. Assuming biofuels are carbon neutral may worsen irreversible impacts of climate change before benefits accrue. Instead, explicit dynamic models should be used to assess the climate impacts of biofuels.
MIT Department
Sloan School of Management
Terms of Use
Creative Commons Attribution 3.0 Unported license
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/1748-9326/aaa512
