Bornholm combines biomass, wind and solar

Date: 6 March 2017

Island energy: Bornholm will be CO2-neutral in 2025 – without additional onshore wind. Bornholms’ Energy & Supply is analysing alternatives on its own simulation tool and the first calculations show that there is room for more solar cells in the grid than expected.

“We must have more learning and knowledge in the system. It is vitally important and fortunately we are making good progress.” Managing director Rasmus Sielemann Christensen of Bornholms’ Energy & Supply is insistent, and you feel that he would cast the message in stone if he could: That it is vitally important to increase the level of knowledge, not just in the supply company, but also in the energy system and on Bornholm as a whole. Bornholm is situated in the Baltic Sea a good distance away from the rest of Denmark, and in terms of electricity, the island has closer links with Sweden. It happens now and then that undersea cables fail, leaving approx. 40,000 Bornholm residents stranded. Completely alone. “It makes us vulnerable, and our grid has to work. We are in the process of analysing how we can increase uptime, for example through service/maintenance and new plants”, says Rasmus S. Christensen.

CO2-neutral without more wind turbines
The Bornholm Regional Municipality, which owns the supply company has declared the island a “Bright Green Island” in order to attract new residents and tourists – in other words to create growth and jobs to avoid the island entering a downward spiral. The local politicians have set a target for the island to be CO2-neutral by 2025. The task has been more difficult following a decision that no more turbines must be erected on land in order to protect the unique nature on the island. A majority in the local council thus removed one of the cheapest means of producing electricity – and has thrown Bornholms’ Energy & Supply into unknown territory.

“We are willing to take responsibility for establishing some sustainable solutions. We have a simulation tool with data for both energy consumption and energy production. We use this to look at how far we can go without more wind power, and we have already learnt some important things. For example, it is evident that there is room for much more solar energy than we thought, and that solar power stations fit better in the energy system than expected,” says Rasmus S. Christensen.

The simulation tool is also used for grid planning by the group’s grid operator Bornholms El-Net, as well as for research and development including with PowerLab at DTU and in EcoGrid 2.0.

Flexible power consumption
Long-term reliability of supply on Bornholm and other areas with a high share of renewable energy depends among other things on whether more flexibility can be introduced into consumption. Therefore, there is great anticipation for EcoGrid 2.0, where 1,000 Bornholm families will make their heat pumps and electric radiators available for an experiment in intelligent control of the future system, where the mix will be biomass-based CHP as the base load for varying production from the wind and sun.

Whether or not Bornholm achieves its climate goal in 2025 remains unclear, but the island’s electricity and district heating supply is part of this goal. Wind turbines cover up to 90 GWh per year and solar cells so far contribute almost 10 GWh. The important CHP plant in Rønne has just been converted from coal to sustainable biomass, so most of the electricity consumption of approx. 230 GWh will be covered with green electricity. The island’s district heating is produced on the basis of typical local wood chips and straw, so this is also fine in climate terms. Around people’s homes there are still several thousand oil-fired burners, just as the transport sector for the most part runs on petrol and diesel, even though electric vehicles otherwise fit in well with many Bornholm residents’ driving patterns. If the CO2 balance is to go neutral in 2025, the electricity sector must compensate with much more CO2-free production, and this may be done with solar power parks. “Bornholm is Denmark’s sunshine island. We have more hours of sunshine than the rest of the country, but the politicians will have the final say in whether we invest in solar power parks. Technically, it fits in well with our supply system,” says Rasmus S. Christensen, who could benefit financially by the price trend for solar cells.

The latest tenders in Denmark was won by solar cells, to supply electricity at the market price plus just 12.3 øre/kWh. Traditionally, Bornholm energy companies have owned the island’s production plants, but Rasmus S. Christensen is open to more cooperation with external project developers. “For us it is more important to ensure good interaction between the plants and a high reliability of supply than to actually own the plants,” he says.

Smart electric vehicles
Multi-supply company Bornholms’ Energy & Supply is the result of a recent merger between the electricity supplier Østkraft and the district heating company Bornholms Supply. New company – New strategy: “We have brought our research and development activities together in one department. The idea is that on the one hand they should think across the traditional supply types, and on the other hand they should have a positive knock-on effect on our operations, but not necessarily in the short term,” says Rasmus S. Christensen, and mentions that the company has just participated in an international project on the smart control of electric vehicles: Vehicle-to-Grid (V2G).

Together with an international partner, Bornholms’ Energy & Supply is also well ahead with simulations of battery technology opportunities in relation to the electricity grid, and experiments with combined solar cell and battery installations may be next on the list. According to the director, participation in this kind of research, development and demonstration will attract knowledge-based jobs as well as energy and climate tourists to the island. “As I said: We are well into the process of bringing more knowledge into the system,” says Rasmus S. Christensen.

Source: The Danish Energy Association