Energy Island for large-scale electricity storage
Electricity storage has substantial added value for the energy sector. Storage increases the technical reliability of energy supplies. Storage also stabilizes the cost of electricity and contributes to the reduction of CO2 emissions.
Inclusion of electricity storage capacity within the power supply system has many environmental benefits, especially when a large amount of the power comes from wind energy. Being able to store electricity means that power stations less often need to be taken offline, especially at night, or run at a low capacity. Stored electricity can be used in the daytime, reducing the costs to meet demand during peak periods. This increases the energetic efficiency of electricity production. Storage also means that the output from wind farms can always be utilized. That, in turn, reduces reliance on other sources and therefore cuts total CO2 emissions associated with electricity production.
DNV KEMA and the civil engineering firm Bureau Lievense collaborated with the designers Gebroeders Das on an innovative concept for large-scale electricity storage: the Energy Island. This Island contributes to the technical reliability of energy supplies, the stabilization of the cost of electricity, and the reduction of CO2 emissions. The first result of our study for the energy companies was a conceptual design for an Energy Island in the North Sea, off the Dutch coast. The Island has numerous other potential uses, varying from renewable energy to port facilities, and from nature to tourism.
The Energy Island will essentially consist of a ring dyke, sealed with bentonite, enclosing an area approximately 6 kilometers long and 4 kilometers wide. To prevent groundwater entering the enclosed lake by percolating through the substrata, the Energy Island will be sited over a layer of clay tens of meters thick beneath the seabed. The water level in the inner lake will be between 32 and 40 meters below that of the surrounding North Sea. When there is a surplus of electricity, sea water will be pumped out of the lake into the surrounding sea; when there is a shortage, sea water will be allowed to flow into the lake, driving a generator. The storage capacity will be sufficient to provide an average of 1,500 MW to the onshore power grid for at least 12 hours.
From the first study, it is clear that a large-scale storage facility in the form of an Energy Island is technically realizable. Key factors determining the feasibility are the presence of a layer of clay tens of meters thick beneath the bed of the North Sea. The technical feasibility of the engineering work involved has already been demonstrated in practice, and suitable pump generators are already available.
> DNV KEMA, the Netherlands
> Bureau Lievense, the Netherlands
> Gebroeders Das, the Netherlands
> Subsidized by Dutch energy sector and we@sea
> Duration: 2006 – 2007