a b s t r a c t An extended Life Cycle Assessment (LCA) is performed for evaluating the impacts of a woody biomass supply chain for heating plants in the alpine region. Three main aspects of sustainability are assessed: greenhouse gas emissions, represented by global warming potential (GWP) impact category, costs and direct employment potential. We investigate a whole tree system (innovative logging system) where the harvest of logging residues is integrated into the harvest of conventional wood products. The case study is performed in Valle di Fiemme in Trentino region (North Italy) and includes theoretical and practical elements. The system boundary is the alpine forest fuel system, from logging operations at the forest stand to combustion of woody biofuels at the heating plant. The functional unit is 1 m3 solid over bark of woody biomass, delivered to the district heating plant in Cavalese (Trento). The relative sustainability of traditional and innovative systems is compared and energy use is estimated. Results show that the overall GWP and costs are about 13 kg CO2equivalent and 42 euro per functional unit respectively for the innovative system. Along the product supply chain, chipping contributes the greatest share of GWP and energy use, while extraction by yarder has the highest financial costs. The GWP is reduced by 2.3 ton CO2equivalent when bioenergy substitutes fuel oil and 1.7 ton CO2equivalent when it substitutes natural gas. The sensitivity analysis illustrates that variations in fuel consumption and hourly rates of cost have a great influence on chipping operation and extraction by cable yarder concerning GWP and financial analysis, respectively. This is confirmed by sensitivity analysis. Better technologies, the use of biofuels along the product supply chain and more efficient systems might reduce these impacts. Replacing the traditional system with the innovative one reduces emissions and costs. A low energy input ratio is required for harvesting logging residues. The direct employment potential is a conflicting aspect and needs further investigations. IntroductionInternational and national policies support the utilization of renewable energy and bioenergy for several purposes i.e. climate change mitigation, energy supply security and energy source diversification. The Kyoto protocol agreement (United Nations, 1998), the European Union target of a 20% reduction in greenhouse gas emissions (GHG) emissions, energy consumption and energy based on fossil fuels (European Union, 2009), and the assumption of carbon neutrality for biomass (International Energy Agency, 2007) are the main drivers behind the implementation of bioenergy production. Along the Alps, local communities show high levels of awareness regarding renewable energy sources, while provincial policy-makers have a keen concern for environmental protection, and are open to the use of bioenergy for mitigating the effects of global warming.

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However studies shows that there are difficulties concerning the profitability in the sector.We approach the question from a supply chain perspective using a comparative case method. Five cases of local and regional forest based (wood chips) supply of heat in three regions were studied. The actors in the supply chains normally specialize in one or two stages in the chain and sell fuel and/or heat to municipal institutions and district heating plants. In all cases national financial support was important for releasing critical investments at various stages in the chains. Local political involvement was vital for the establishment of the chains, through influencing perceptions and ideas and through various techno-economical adaptations. Moreover, all focal actors in the chains were engaged in forest-related businesses and they benefit from using resources and obtaining income in different, related supply chains. Hence, they exploit "economies of scope". The links across supply chains make it relevant to study them as supply networks rather than chains. This also has managerial consequences. The profitability in the chains seems still quite modest, but nevertheless they contribute in increasing the share of bioenergy in Norway. Actors' exploitation of "economies of scope", local political engagement and national instruments for financial support are important factors in this development. ª

Norwegian mountain forests represent interesting sources of wood biomass for bioenergy. This case study gives a life cycle assessment of the greenhouse gas (GHG) emissions and costs of forest management, harvest and transport operations in the mountainous areas of Hedmark and Oppland counties in Norway. Low-intensity forest management characterizes the study sites. The study shows that transportation to the terminal is the operation with the highest GHG impacts in the examined supply chain and that the bundling of forest residues has the highest financial cost. The mountain forest system analyzed emits 17,600 g CO2e per solid cubic meter over bark. Transportation to the terminal accounts for 31% of the emissions and 23% of the costs, while bundling accounts for 25% of the total emissions and 19% of the total costs. The study shows that there is a considerable quantity of woody biomass available for bioenergy purpose from mountain areas. In the short term, it is possible to integrate harvesting of logging residues in the conventional logging operations. However, it is necessary to improve forest management, logistic and technology for reducing emissions and operative costs, ensuring the achievement of a sustainable system at the same time.

Case studies of mountain forest wood fuel supply chains from Norway and Italy are presented and compared. Results from previous studies in which greenhouse gas emissions and costs were evaluated using life cycle assessment and cost analysis respectively, are compared. The supply chain is more mechanized in Norway than Italy. Steeper terrain and low road density partly explain the persistence of motor-manual felling in the Italian case. Mechanized forest harvesting can increase productivity and reduce costs, but generates more greenhouse gas (GHG) emissions than motor-manual harvesting. In both cases, the main sources of GHG emissions are truck transportation and chipping. The total emissions are 22.9 kg CO2/m3s.o.b. (Norway) and 13.2 kg CO2/m3s.o.b. (Italy). The Norwegian case has higher costs than the Italian one, 64 €/m3s.o.b. and 41 €/m3s.o.b. respectively, for the overall supply chain. The study shows that mountain forests constitute an interesting source for fuel biomass in both areas, but are a rather costly source, particularly in Norway. The study also exemplifies the care needed in transferring LCA results between regions and countries, particularly where forest biomass is involved.

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