Lighthouse island 2: Bornholm
Location and general description:
Bornholm is a Danish island located in the Baltic Sea counting with more than 40.000 inhabitants in a total area of 588,3 km2.
The business structure in Bornholm is based on tourism, agriculture and transport with some production companies, a growing sector with specialized food products and gourmet restaurants, and a historic but still thriving arts and crafts sector. In this sense, Bornholm is the sixth biggest tourist destination by revenue of Denmark4.
Regarding the energy system on the island, BEOF is the distribution system operator and the power grid data is available by PowerLabDK, a research platform operated by DTU. The distribution grid includes a meshed 60 kV network with 16 60/10 kV substations, 91 10 kV feeders and approximately 1000 10/0.4 substations. It is connected to mainland (Sweden) by a 120/60 kV cable. Finally, Bornholm counts with a Bright Green Island Strategy Plan.
Demand and consumption:
The electricity system in Bornholm consists of 28.000 electricity customers (56 MW peak load) and has a very high penetration of a variety of low-carbon energy resources, which enables a 65% share of variable RES in the final electricity consumption.
In 2017, the electricity demand was in average 26 MW with a total consumption of 236 GWh.
Electricity consumption under normal conditions is fed by five sources of energy
Generation capacities in Bornholm include 38 MW of wind turbines, a 2 MW biogas plant, a 37 MW steam turbine fed 100% by wood chips, 14 back-up diesel generators with a capacity of 34 MW and a 25 MW back-up steam diesel turbine. Diesel units together with the steam units are able to control voltage and frequency, while the newest wind turbines are able to control active and reactive power.
In addition, Bornholm district heating has been expanding during the last years and, currently, it covers more than 80% of households. Fuels used for the district heating include woodchips, straw, waste incineration and biogas. The grid is expected to provide about 325.000 MWh/year.
Electric vehicles infrastructure: there are 36 chargers on Bornholm, of which 15 are accessible to the public and the rest are owned by the municipality and used for their service-cars. The distribution of chargers on the island is mainly focused in Roenne (29 chargers). In addition, there are 21 V2G chargers of 10kW currently installed.
Bornholm municipality aims becoming 100% sustainable and neutral carbon by 2025.
First of all, the current need of diesel generators for the control of voltage and frequency impedes a 100% renewable operation of the island, which must be tackled through new approaches making use of batteries, new power electronics and RES providing ancillary services to the grid.
Secondly, the transport sector would remain as one of the most important CO2 contributors, so its further electrification will be key to reduce the use of fossil fuels.
Bornholm can be considered as a model of the Danish society and, due to a high investment through the last 10 years in decarbonisation, it can be also considered as a model for the near future energy system not only in islands but also in mainland areas with a high share of local RES generation.
Bornholm already counts with a strong grid monitoring system supported by an experimental platform for electric power and energy. Together with the multi-utility structure embodied in BEOF it eases the collection and comparison of data for the validation and replication of INSULAE solutions.
Innovations addressed and solutions to be implemented:
Technical University of Denmark.
Bornholms Energi of Forsyning.