Energy

Biomass district-heating

A district heating system consists of a transport network and a heat production plant, which serves more than one building at the same time. The district heating plant can use co-generation technologies and/or renewable sources.

The installations
The heat that is distributed by urban district heating systems derives from simple production installations (only heat) and combined production installations (heat + electric energy).
The first type of installations includes boilers for the production of heat as vapour, hot water, superheated water, oil.
Combined production installations, instead, are co-generation plants that in today practice can be fed by a vapour cycle with internal combustion motors, gas turbines, with a combined cycle.
The distribution network is the most expensive part of the district heating plant: its cost should amount to 50-80% of the total investment. The distribution system can use different types of fluids: the trend in Italy is to use hot water (80-90°C), or slightly superheated (110-120°C).

Heat distribution
The distribution system can be direct or indirect. In the first case, a single hydraulic circuit connects the production plant with the user’s heating body (radiator or plate). In the second case, there are two separate circuits that are in contact through a heat exchanger. The direct system requires a lower investment and causes fewer heat losses.