Green Christiansø


For Danish Ministry of Defence activities, including Christiansø, the Ministry has laid out a series of green strategies covering climate, energy, nature and the environment. 

Furthermore, the archipelago is subject to significant building and wildlife protection provisions and has been designated by the EU as a NATURA 2000 nature protection area. 

Christiansø is thus one of the most well-protected nature and cultural reserves in Denmark, and the Ministry of Defence is continually working to implement greener solutions in the area. 

Renewable energy is the goal

Today, residents and the many thousands of visitors to the island get their power and heating from the island’s own combined heat and power station. The CHP station, which is located at Vagten near the church, runs on diesel and therefore does not meet the political goals of a fossil-free Denmark.

One of the island’s three old diesel engines at the power station.

The goal is to transition the energy supply away from fossil fuels and towards a more renewable energy solution. 
However, the nature reserves and listed buildings present a challenge when it comes to finding the right solution.

Wind energy

In recent years, the vision has been to replace fossil fuels with renewable energy in the form of wind power. 

An investigation is therefore underway to determine the feasibility of establishing a wind farm, which, combined with hydrogen storage and fuel cells, can make Christiansø Fortress 100% self-sufficient and carbon neutral.

View of the sea north-west of Ertholmene.

A series of other optimisations are also planned for the utility supply. These include connecting Frederiksø to the district heating network under the harbour and establishing a new wastewater system.

Water was once scarce on the island

Drinking water on Christiansø was once scarce. Up until a few years ago, the water supply was based solely on surface water from the many water basins and dams on Frederiksø and Christiansø. At that time, the water was more brown than clear, had an after-taste and required treatment and the addition of chlorine to make it drinkable. 

During very dry summers, these basins sometimes dried up, making it necessary to sail water in from Bornholm. Seawater was therefore used in toilets and the like to conserve fresh water.

Osmosis water filtering system at the harbour.

The drinking water system has now been modernised and the water is a mix of desalinated water from the Baltic Sea (approx. 80%) and water from wells on Christiansø (approx. 20%). Seawater is desalinated in an osmosis water filtering system at the harbour. From there, the water travels to the waterworks (converted in 2013), located in the middle Christiansø, where it is mixed with well water.

Today, the islands are 100% self-sufficient with fresh, clear drinking water, and after a visit to Christiansø, you can rightly claim that you have drunk from the Baltic Sea.

Store Brønd/Guds Forsyn, the largest water basin on the island. The waterworks are located here.