Integration potential, resource efficiency and cost of forest-fuel-based biorefineries

• A multidisciplinary study of a biorefinery producing ethanol from forestry residues.
• Process design, economics, feedstock supply and system integration were considered.
• Biogas, carbon dioxide, pellets, electricity and heat were produced as co-products.
• Large amounts of heat were difficult to integrate with district heating systems.
• Locally feedstock supplied plants have to be placed in northern or central Sweden.

A multidisciplinary study of the implementation potential of a biorefinery, using forestry residues as feedstock, is performed by assessing techno-economic factors, system integration and feedstock supply. The process is based on biochemical conversion of logging residues to produce ethanol, biogas, pellets, heat and electricity. Nine models were designed in Aspen Plus based on the available feedstock and the required co-products. Focus was on the product ratio of pellets and heat. The net present value of the plants was calculated and thermal integration with district-heating systems in areas with regional feedstock availability was investigated. Also co-location with pulp and paper mills in Sweden was investigated to replace fossil fuels with pellets. Seven of the nine models showed a positive net present value assuming an 11% discount rate and 30% corporate tax. Five counties in Sweden were identified as potential feedstock suppliers to a biorefinery processing 200 kt dry feedstock/y.

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