Hybrid power system on Danish off-grid island.

The challenge is not power generation in itself which relies on well-known, tried and tested technologies, including renewables such as photovoltaics. “The real challenge is to find a controller that can balance everything so that when a cloud blocks out the sun, for example, another power source is ready to take over”, says Birgitte Palle Nielsen, project manager of Grøn Livø, an ongoing development project on the Danish island of Livø. Managed by the Nature Agency under the Ministry of Environment and Food of Denmark, the project is carried out in cooperation with Aalborg University and engineering companies COWI and Intego and funded in part by the Danish Energy Technology Development and Demonstration Programme.

Located approximately 4 kilometres from the coastline, the 320-hectare island of Livø is not connected to the mainland grid, and reliable power and heat must be generated locally. Adding to this challenge is the fact that while the island has only a handful of permanent residents, around 20,000 people visit over the summer, attracted by the beautiful scenery and annual events such as a jazz festival. The result is dramatically increased power consumption and significant load variations, and the island utility staff need to handle these fluctuations on their own.

“I’ll give you one small example”, says Jacob G. Knudsen who is responsible for most of the utility installations on the island. “The permanent residents consume around 13 kW on average, but the dishwasher at the inn consumes another 13 kW on its own. If someone starts it up, power consumption doubles just like that”.

Updated energy mix with DEIF power management

At the start of the project, the outdated diesel genset that had previously supplied all power on Livø, and which had clocked 120,000 running hours, was replaced by three smaller gensets supplying a maximum total output of 36 kW. In addition, a 25 kW wind turbine and a 33 kW photovoltaic panel were added to the energy mix. The setup also includes an electrical boiler that converts surplus power to hot water which is then stored in a 32 m³ thermal storage tank.

Towards 100% renewable energy self-sufficiency

When the new setup becomes fully operational in the autumn of 2019, the island is expected to achieve 50% renewable energy self-sufficiency. There have been no operational issues; in fact, the DEIF controllers have given the island utility staff less to worry about. “The power management features are quite important to us”, says forest guard Martin Olsen who assists Jacob G. Knudsen during utility emergencies. “When everything is running as it should, you forget that the controllers are there. When something goes wrong, you are thankful that you have all these control options at your disposal!”