Integration of Biomass Upgrading Processes with Communal CHP Plants – Influence on Energetic and Environmental Performance

In order to react on high future biomass prices, communal CHP plants can be integrated with biomass upgrading processes that add valuable products to the portfolio. In this paper, outgoing from a base case, we simulate the retrofit integration of wood fast pyrolysis slurry, torrefied wood pellets and wood pellets production with an existing wood-fired CHP plant. Free boiler capacity during low district heat demands is used to provide energy for the upgrading processes. By detailed part-load modelling critical process parameters can be obtained. With help of a multiperiod model of the heat duration curve, the work shows the influence of the integration on plant operating hours, electricity production and biomass throughput. Environmental and energetic performance is assessed according to EN 15603 and compared to the base case. According to the simulation results integration is well possible in between the operational limits of the plant. Further, results show that yearly operation hours can be extended by 25-36%, but that annual power output is decreased by approximately 10% due to the power requirements of the additionally installed equipment. Production of wood pellets gives highest product yield and, for the evaluation method used, performs best energetically and environmentally. For more entire evaluation economic data must be added which will be part of our future work.