A Hole In The Ocean To Store Energy
Imagine you’re looking for treasure on a small island in the middle of an ocean. The highest elevation on the island is just above sea level, which is rising because of global warming. (You’d rather not see that happen.)
In the middle of that island you dig a hole where the tattered map says the treasure should be. Dig, dig and dig you go, and soon you’re way over your head and all you can see is the blue sky above, and the walls of sand and dirt around you.
No treasure to be found.
Suddenly you have a revelation. The hole you’ve dug is deeper than the surface of the ocean around your little island. Should the skies turn cloudy and a storm come in, the ocean could come pouring into your hole. You’d be in deep trouble in your hole in the middle of the ocean.
But you have a second revelation, you’ve invented an energy storage device. What if you dug a large and deep hole in an island - on an ocean or big lake - and purposely allowed the surrounding body of water to flow in, but at your discretion and through pipes and hydroelectric turbines. As the water flowed you be generating power. When filled your deep hole, or reservoir, would be pumped out into the surrounding ocean by another source of energy, perhaps wind turbines or excess capacity on the shore-side power grid. In effect you be storing the energy from those sources.
Your little island with a deep lake in the middle is your energy storage device, your energy island. In the long term it could provide more revenue than the chest of gold you never found.
KEMA, a global provider of business and technical consulting, is working in partnership with civil engineering firm Bureau Lievense and technology illustrators Rudolph and Robert Das to develop the Energy Island concept; more technically known as an Inverse Offshore Pump Accumulation station (IOPAC). The concept is a relative (and sort of the inverse) of onshore pumped storage hydroelectric facilities where water is pumped to high elevation ponds with surplus power, then released when needed for peak power demands on the grid.
The Energy Island would be built of dikes made with dredged seabed, then the reservoir deepened, and dikes fortified, with more dredging and digging.
The concept is part of an ongoing feasibility study by Dutch energy companies. At the site being considered in the North Sea, a 150 meter (500 feet) deep reservoir would be built in the artificial island. According to KEMA the proposed Energy Island storage system would have a maximum generation capacity of 1,500 megawatts, depending on the water level. It would have an annual storage capacity of more than 20 gigawatt hours – enough energy to offset 500 to 840 kilotons of CO2 emissions. The energy stored could come from a ring of turbines planted on the surrounding dikes, from the onshore power grid or from another offshore wind farm.
In the next phase of the feasibility study already underway, KEMA is analyzing additional costs and benefits, CO2 reduction, and environmental impact. KEMA is headquartered in Arnhem, the Netherlands, with offices in the US and elsewhere.