A biomass central in Varna, not just a district heating

Enertour destination - In Varna, a municipality of 4.200 people in the Isarco valley (BZ), a biomass district heating central came into operation in December 2008; this central not only provides the village with heat, but also produces electricity.

The heart of the central is a biomass boiler of 6.500 kW, which works with untreated wood (such as wood chips, bark and sawdust) from sawmills and forestry workings from the area. In support of this boiler there are two auxiliary boilers of natural gas, each with a thermal power of 7,500 kW, which are used to cover the peaks of demand and as a reserve in case of breakdown or failure of the biomass boiler. The annual production of heat power station is of 30,000,000 kWh. The contribution of the auxiliary boilers of natural gas is approximately 2%.

The central of Varna also produces power thanks to a group of ORC (organic rankine cycle) turbogenerators. The heat produced by the biomass boiler is used inside the closed loop of the ORC to evaporate a silicone oil. When the high-pressure gaseous state is being reached, the fluid expands in the turbine, generating electricity and is then condensed, while giving up heat to the circuit of the district heating network. Thanks to this highly efficient technology in Varna, with approximately 5,000 kW of thermal power 980 kW of electrical power can be generated and a thermal power of about 3,800 kW is retrieved. With the use of the ORC group the biomass power central can produce annually 5,000,000 kWh of electricity.

The central is managed by the Department of Public Works of Bressanone and its network of heat distribution has been linked to the district heating network of the adjacent municipality of Bressanone. This way, the district heating network serving Varna and Bressanone reached the length of 120 km, allowing to deploy more than 70 million kWh per year of thermal energy and to serve 1700 users, including 1,400 in Bressanone and 300 in Varna.

Client: Teleriscaldamento Varna – Bressanone
Central planning: Studio EUT, Bressanone (BZ)
Network planning: Engineering Office Bergmeister, Varna (BZ)

For the tour: enertour@tis.bz.it

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