Energetic and environmental performance of three biomass upgrading processes integrated with a CHP plant

• Published in: Applied energy 2013-07, Vol.107, p.124-134
• Main Authors: Kohl, Thomas, Laukkanen, Timo, Järvinen, Mika, Fogelholm, Carl-Johan
• Format: Article
• Language: English
• Subjects: Applied sciences; Biomass; biomass production; carbon dioxide; Combined heat and power (CHP); Combined power plants; electricity; Energy; energy efficiency; Energy. Thermal use of fuels; environmental performance; Exact sciences and technology; Fast pyrolysis; fuels; greenhouse gas emissions; heat; Installations for energy generation and conversion: thermal and electrical energy; integration; Natural energy; pellets; Polygeneration; primary energy; pyrolysis; slurries; wood; Wood pellets; Wood torrefaction
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2013.02.021

► We simulate CHP-integrated production of wood pellets, torrefied wood pellets and pyrolysis slurry. ► Integration increases operation hours and district heat output by up to 38% and 22%. ► Additionally installed equipment reduces yearly power generation by up to 7%. ► Wood pellet production performs best energetically and environmentally. ► Integrated concepts substantially reduce fuel consumption and CO2 emissions. In order to react on future expected increased competition on restricted biomass resources, communal combined heat and power (CHP) plants can be integrated with biomass upgrading processes that add valuable products to the portfolio. In this paper, outgoing from a base case, the retrofit integration of production of wood pellets (WPs), torrefied wood pellets (TWPs) and wood fast pyrolysis slurry (PS) with an existing wood-fired CHP plant was simulated. Within the integration concept, free boiler capacity during times of low district heat demands is used to provide energy for the upgrading processes. By detailed part-load modelling, critical process parameters are discussed. With help of a multiperiod model of the heat duration curve, the work further shows the influence of the integration on plant operating hours, electricity production and biomass throughput. Environmental and energetic performance is assessed according to European standard EN 15603 and compared to the base case as well as to stand-alone production in two separate units. The work shows that all three integration options are well possible within the operational limits of the CHP plant. Summarising, this work shows that integration of WP, TWP and PS production from biomass with a CHP plant by increasing the yearly boiler workload leads to improved primary energy efficiency, reduced CO2 emissions, and, when compared to stand-alone production, also to substantial fuel savings.