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Directory:KEMA's Inverse Offshore Pump Accumulation Stations
Page first featured January 28, 2009
Some power companies pump river water up into a reservoir to store energy generated at low usage times such as at night from a renewable energy source such as a wind or solar farm. The water can then generate power as it comes back down through the hydro turbines to cover base load needs of the community being served.
Now a Dutch energy consulting company, KEMA, founded in 1927, is exploring the possibility of putting this principle to work but in an inverse way, using the sea, a dike, and a lower-than-sea reservoir. During times of energy surplus, sea water would be pumped out of the reservoir into the surrounding North Sea, until it was completely empty. Letting the sea flood back in via turbines emplaced in the dykes could generate 2 gigawatts or more for up to 15 hours at a stretch. In other words, the "Energy Island" could store about 30 gigawatt-hours.
And rather than take up valuable beach real-estate, this inverse offshore pump accumulation station (IOPAC) will be stationed on an artificial island at sea.
The Energy Island, designed by KEMA, Lievense and the Das brothers, is presented as an innovative concept that can be attractive in the medium and long term for the Dutch electricity supplies. In a subsequent stage, a detailed location study is planned and the technical capabilities and economic and ecological values of the other functions will be investigated. 
- The Energy Island - an inverse Pump Accumulation Station - 5-page PDF
How it Works
Quoting from KEMA.com
- Pump generators
- "The principle of the subsurface-lake power station is made technically possible by using the several tens of meters thick clay layer under the floor of the North Sea. When there is a surplus of electricity, sea water is pumped out of the lake into the surrounding sea; when there is a shortage, sea water flows into the lake while driving a generator. The pump generators required are commercially available.
- "In the first design for the energy island, KEMA and the Lievense bureau extended on the established techniques of the dredging industry. The storage capacity is sufficient to provide more than 12 hours of power at a capacity of 1,500 MW, comparable to the capacity of a large electricity power station in the Netherlands."
Quoting from KEMA.com
- Environmental advantages
- "The addition of electricity storage in the electricity net has many environmental advantages, especially in combination with a large amount of wind energy in the electricity system. In this situation electricity power stations need to be taken offline less often, especially at night, or run at a low capacity. By day the stored electricity can be used as a result of which no extra peak power station needs to be used. This increases the energy efficiency of electricity production. The production of wind energy can moreover be used at any moment."
Quoting from KEMA.com
- Enormous savings
- "Scenario analyses for the year 2020 show that ‘The Netherlands Ltd.’ can make enormous annual savings on operational costs when electricity storage is an integral part of the electricity system. The cost saving becomes larger as [fuel] price increases. Instead of replacing one or more existing peak power stations (or building a new one) investment can also be made in a large-scale storage system."
Quoting from http://www.kema.com/corporate/company_profile/
- "'How will the demand for power develop in the years ahead? How do I best balance the risk of equipment failure against maintenance or capital replacement choices? Answering questions such as these is KEMA’s core business. KEMA is intensively involved in these processes as an energy consultant and a specialist in testing and certification.'
- "KEMA started life in 1927 as the Dutch electricity industry’s Arnhem-based test house. Originally just an abbreviation of the company’s full Dutch name, the letters K-E-M-A have since come to stand for much more than the testing of electrical equipment. While electrical safety testing and certification are still among KEMA’s core activities, today’s globally active company provides a host of independent applied research and consultancy services via an international network of subsidiaries and agencies.
- "KEMA is a commercial enterprise, specializing in high-grade business and technical consultancy, inspections and measurements, testing and certification. Much of the company’s work centers round innovative technology. As an independent organization, KEMA supports clients concerned with the supply and use of electrical power and other forms of energy."
The study into this innovative concept has been carried out with financial contributions from the energy companies Delta, Eneco, Nuon, E.ON Benelux, EPZ, Essent and TenneT and with a subsidy from the We@Sea Foundation (Stichting We@Sea). 
In the News
- Featured: Storage / Offshore Wind / Energy Islands >
KEMA's Inverse Offshore Pump Accumulation Station - A new concept is being explored that would use excess renewable energy to pump water out of a lower reservoir into the surrounding sea as a storage mechanism. This artificial inverse island is being considered for off shore deployment in the North Sea. (PESWIki; Jan. 28, 2009)
- Dutch plan 'Energy Island' - A Dutch company has proposed an interesting new kind of pumped-storage energy station. Normally, such facilities work by pumping huge uphill reservoirs full of water and letting it flow out through hydro-power turbines later on to release the stored energy. This one, however, works by emptying a huge reservoir. (The Register; Nov. 11, 2008)
- The Energy Island: A Gigantic Offshore Battery? - There is something new and innovative here. KEMA, Lievense and the Das brothers have designed an artificial island that would, in essence, be somewhat like a Pacific atoll, but the inner water surrounded by the outer ring would be sealed off from the larger ocean. (EcoGeek; Oct 2, 2008)
- Tapping The Source: The Power Of The Oceans - An obvious extension would be to harness ocean energy as well - letting wave and/or tidal power supplement the output of the wind turbines. An attraction of this concept is that it potentially allows a large amount of new energy storage to be brought online - and this storage would be along the world's coastlines, where most of the population lives. (The Oil Drum; Feb. 25, 2008)
- Putting a Turbine in the Dike - (Peak Energy; Aug. 2007)
See Discussion page