1. Biomass heat networks

The operating principle of a biomass heating network is similar to that described at [TBA 2 674] , with a main boiler room usually fuelled by wood chips. This main production unit is combined with a back-up unit for peak periods. Some biomass boiler plants also produce electricity, with a cogeneration plant or module.

The majority of biomass heating networks today are small-scale (80% with a capacity of less than 3 MW, 3 out of 4 located in towns with fewer than 5,000 inhabitants), but large-scale wood-energy boilers are emerging to supply larger urban networks, often replacing older fossil-fuel boilers (figure 1 ).