Location: East coast of Bornholm

Area: App. 10 km2

Number of inhabitants: App. 2.500

Climate: Temperate coast-climate

Pilot led by: Bornholms Varme

Energy Mix & Infrastructure

Existing infrastructure: Power

  • 37 MW from 35 larger wind turbines. Private and public owned
  • 8 MW from app. 1.000 rooftop PV stations
  • 15 MW from two private PV production plants + 20 MW planned PV plant
  • 3 MW from Biogas plant
  • 35 MW from woodchip fueled boiler
  • 58 MW capacity of fossil fuel generation

Existing infrastructure: Heat

  • 4 MW straw fueled boiler (with condensation). Production: 18.000 MWh / year
  • 2,4 MW electric boilers (backup)
  • 1-2 MW wood pellet fueled boiler (backup)
  • 80 MWh in hot water storage tank – 1.500 m3
  • 93 kW heat from rooftop PV

Renewables penetration

Bornholm already has a very high penetration of RES today:
Local electricity production is based on biomass (16%), wind (44%) and sun (13%), and covered 75% of the electricity consumption in 2020. The small production (2%) on fossils takes place on the CHP, in periods when the sea cable is unconnected, or the Danish ENERGINET calls for increased power input to balance the Danish grid. Total electricity consumption is about 240 GWh / year.

District heating is based on local renewable biomass (straw and wood chips) and a little waste incineration. Total District Heating consumption is about 300 GWH / year.

Energy Agenda

On Bornholm a group of citizens, with support from the municipality, are now developing a 100 MW Wind turbine park (offshore) based on local funding, to be ready in 2025. New PV-parks are also planned.

Relative Activities

In this pilot tests will demonstrate local services of power control, peak shaving and optimizing use of renewable biomass and solar power, by means of intelligent control capability. Forecast of production from a PV plant by means of meteorological data and measurements of irradiance, will be used for the control of electrical boilers in Østerlars heat plant, for balancing and absorbing the fluctuating electricity production, and store it as heat in the district heating system. The case is replicable in all Islands (and geographical areas) with district heating – with or without a power cable to the mainland.

The District heating consumers in the Østerlars grid all have remote read digital meters, enabling detailed analysis of data about consumption, temperatures, and flow in the grid. The consumers are also equipped with identical “heat-units” containing 100-liter hot water storage tanks, and Danfoss ECL computes controlling the charging of the tanks, and temperature level of incoming water to the household radiator system.

A number of consumers in Gudhjem (energy community) will be recruited for the demonstration, and upgraded with remote controls, to provide access to demand-response in the grid, for balancing heat input from PV via electric boilers. Two larger consumers are already recruited: The public indoor swimming pool in Gudhjem, and the local school in Østerlars. On the production side short time solar forecasting of a planned 20 MW PV plant will enable peak shaving and avoids reinforcement of the weak electrical grid, by means of controlling the 2.4 MW electric boilers.