Presentation on theme: "1 1 Is biomass from boreal forests better or worse than fossil fuels from a climate perspective? A work in progress By Bjart Holtsmark Statistics Norway."— Presentation transcript:
1 1 Is biomass from boreal forests better or worse than fossil fuels from a climate perspective? A work in progress By Bjart Holtsmark Statistics Norway
2 The traditional starting point Sjølie, H. K., E. Trømborg, B. Solberg and T. F. Bolkesjø in Forest Policy and Economics 12, 57-66, (2010) “The objective of this study is [..] to analyse [..] the impacts on GHG emissions by replacing one energy unit of fossil fuel with wood fuel in various types of heating facilities.” At the same time they write: “CO2 is excluded in calculation of emissions from combustion [of wood], as wood is considered carbon neutral”. Their conclusion: Increased use of biomass from the Norwegian forest will provide climate benefits. Similar arguments and conclusion found in several recent studies, for example Bright RM, Strømman AH (2009) Life cycle assessment of second generation bioethanol produced from Scandinavian boreal forest resources. J IndEcol 13:514–530 Bright, Strømman, Peters (2011) New paper, taking both CC and albedo into account – work in progress!
3 The forest’s standard parcel An overlapping generations model of trees The model consists of a set of parcels, each of 1 km 2, all with the same properties, but with different time since last clear cutting (age) Productivity follows the Braastad (1975) production tables – probably too small areas - adjusted As dead wood decomposes slowly, this gives accumulation of dead wood in older forests – important part of the forests carbon stock After clearcutting in a parcel the growth path restarts
4 The forest’s standard parcel
Consider an area of 34 000 km2 Two scenarios: No harvest Annual harvest of 6.8 Mm3/year + 1.4 Mm3 residues/year
10 Two examples: First case, the wood is used as the raw material for manufacturing pellets. The pellets then replace coal in power plants In the second case, wood is used for producing second generation liquid biofuels, and replaces petrol or diesel.
12 Next step: Total effect on radiative forcing, taking albedo into account
First conclusion: Harvesting of wood fuels is not a climate neutral activity – even if albedo is accounted for
Next question: Is wood fuels better or worse than fossil fuels?
Second conclusion: Harvesting of wood fuels does not appear to be good climate policy – even if albedo is accounted for and the wood fuels replaces petrol or diesel
Third conclusion: When wood fuels replaces coal, the climate impacts are less clear
25 Background Based on the assumption of climate neutrality, wood fuels from the Scandinavian forest have conventionally, from a climate perspective, been considered as a better energy source than fossil fuels. Policies in order to increase the supply of biofuels through increased harvest from the forest. In this paper I find: Wood fuels are not climate neutral and that continued use of fossil fuels is in most cases a better alternative than increased use of biomass from the forest. Relevance beyond the Scandinavian debate: The Scandinavian forest is part of the vast boreal forests A map of the boreal forests