Economic and greenhouse gas emissions assessment for extraction of excess biomass from future kraft pulp mills
Paper in proceedings, 2002
Different studies have shown that the process heat requirements of future pulp mills can be satisfied using available internal biomass (bark and lignin), which are process by-products. Assuming that biomass is CO2 neutral, further reducing the process heat demand will not therefore lead to further reduction of Greenhouse Gas (GHG) emissions – unless the excess biomass is extracted and used elsewhere to substitute fossil fuels. Previous work has demonstrated the potential to extract and export significant amounts of biofuel from future pulp mills. The associated extraction costs can be competitive with conventional forest fuels. However, biofuel extraction reduces the mill’s potential to cogenerate electric power. This reduced power output must be compensated by increased purchased power from the grid, with associated costs and emissions. Such emissions must be affected to the extracted biofuel, which cannot therefore be considered as CO2 neutral. This paper presents results for costs and associated greenhouse gas emissions for excess biofuel extracted from a pulp mill. The results show that the extraction costs are competitive, but that the greenhouse gas emissions associated with the exported biofuel can be significant and must therefore not be neglected.