Abstract
The present chapter deals with biomass-based technologies for polygeneration and district heating (i.e., DH). The relevant technologies for the generation of heat, power and biofuels are presented in the first section taking into account thermochemical, chemical and biological pathways. In particular, the opportunity of integrating them for polygeneration - also according to the biorefinery concept - is here analyzed. Biomass CHP (i.e., combined heat and power) systems for DH application have been compared considering size, efficiency, flexibility of operation and field experience. In the second section, heat distribution systems have been described taking advantage of the previous analysis on generation technologies and pointing out the existing relation between distribution, generation efficiencies and DH network temperature. The current trend towards low temperature DH systems has been then extensively analyzed. The effects of the possible variation in the heat demand - both in the short term (i.e., daily to seasonal utilization profiles) and in the medium term (e.g., building refurbishment) - on the DH system operation and efficiency, are here presented. The biomass CHP systems are also discussed in the vision to extend the smart grid concept to thermal networks. As a whole, pilot or real plant data and validated theoretical models are used to support the analysis.