ECOPlanet grounds the world’s first ‘energy island’

In the middle of the North Sea a man-made island the size of eight soccer fields is set to rise up from the waves. Belgium’s Princess Elisabeth Island, the world’s first artificial energy island, is being built with 23 concrete caissons made from Holcim’s ECOPlanet low-carbon cement. 

With demand growing for energy, the clean energy transition is at a decisive moment, with operators exploring more sustainable, future-proof solutions. The building sector has a major role to play by increasing access to renewable energy in a sustainable way. 

Since the energy sector is responsible for over 75% of greenhouse gas emissions, projects like this energy island – which will give Belgium access to 3.5 gigawatts of energy generated by offshore wind and allow it to trade this with neighbors – are central to the European Union’s (EU’s) 2050 net-zero target and the European Green Deal.

The challenge 

The project overseen by Elia, which manages Belgium’s power transmission network, involves building an island to host high-voltage direct (HVD) and alternating currents (HVAC). This will sit 45 km offshore and cover 6 hectares. The 23 concrete caissons will form the outer ring of the island, which will also include a small harbor, to allow easy access for maintenance crews. 

Our direct customer TM Edison asked that the 27-m high caissons be built from low-carbon cement, to lower the project’s overall environmental impact. Through its ‘nature-inclusive’ design, Elia has also worked with conservation experts to ensure a positive impact on biodiversity and marine life. 

Constructing Princess Elizabeth Island in the wild North Sea environment presented obvious challenges, both in terms of building solutions and the island’s assembly, that Elia Group, its construction partners and Holcim Belgium worked together to overcome.

The solution 

Following testing by TM Edison, Holcim’s low-carbon ECOPlanet cement with high-sulfate resistant (HSR) cement was chosen to build the caissons due to its durability. This cement will enable Princess Elisabeth Island to withstand the caustic, rough North Sea environment for a guaranteed 100 years, while providing high strength and workability

The 20-kiloton caissons are now being fabricated on dry land, in Vlissingen, The Netherlands, with ECOPlanet low-carbon cement using a slipforming method. This involves continuous pouring of concrete for 24 hours a day, seven days a week, with the Holcim Belgium team on standby to provide quality and logistical support.

Once fully cured, the 23 caissons will be towed out to the installation site, positioned and then ballasted – firstly with water and thereafter with sand and concrete.

The result