Bioenergi från röjningsgallringar : en jämförande studie av fyra flödeskedjor från avlägg till förbrukare

Abstract: When the Swedish Forestry Act was changed in 1994, brushing of young stands became non mandatory. Since then the annual need for brushing in the country has increased by about 100 000 hectares per year. In later years the price for biomass energy has increased to the same level as pulp wood. The high price on biomass energy and the large areas of stands in the need of brushing has created a new market with its own technical, economical and environmental conditions. There is a development of various techniques to manage the forestry stands with late brushing. The purpose of the study is to assess the strategical and operative consequences of four different supply chains, which handle biomass energy from mechanised brushing to the landing at the gates of the heating plant. The demand on biomass energy is strongly correlated to the cold season of the year. In order to keep a steady supply flow a minimal level of storage was assessed. The results show that a supply chain with chipping at the landing and transport straight to the heating plant has the lowest cost. This supply chain has no easily accessible storage. Supply chains with terminal chipping has the ability to meet fluxes due to seasonal changes, bad weather and it to minimise road damage during thawing of frozen gravel roads. A supply system based on a combination of 75 % of the yearly demand from the cheapest supply chain and 25 % of the yearly demand from a system with storage capacity, gives a low cost and high stability in production. Compared with the cheapest supply chain, the combined system gives an increase in the total cost of only 3 % or 5 % depending on the technique used for chipping.