Long-term energy is stored with concrete spheres under the sea
It received 4 million dollars of support from the US Department of Energy to make concrete spheres with a 3D concrete printer, and 3.7 million euros of support from Germany for the pump that drains and fills the water inside the sphere and the machine that will also be the turbine. At the end of the investment, Sperra Energy will try to make a profit by selling electricity at times when it is at its highest price.
The biggest advantage of the technology is that it is similar to the cost of the well-known and frequently used pumped hydroelectric electricity storage facilities, but it is established without the cost of land and relatively without harming wildlife. Another advantage is that you can use such a system modularly instead of building giant reservoirs at once with very high capital.
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The working logic of the system is quite simple. A concrete sphere filled with air at surface pressure is placed at a depth of 700-800 meters. There is a double-sided pump at the bottom. While high-pressure sea water fills the sphere, the pump works like a turbine that produces electricity. When electricity is wanted to be stored, the water inside is pumped out and the sphere is recharged.
In this way, if there is a problem with the pump in the system, which is connected to the surface only with electrical and management cables, only it can be dismantled, moved up and taken for maintenance. The double-sided pump turbine used here is the turbine added version of the deep sea pumps we currently use to extract oil. To produce concrete blocks, the company uses a 3D Concrete pump by the port, thus reducing transportation and production costs.
Although it was the Germans who came up with this idea, it will be the US venture company Sperra Energy that implemented it. The battery blocks will have a width of 10 meters, will be able to produce 500 kW of power, and the amount of energy it stores will be 600 kWh. The sea depth where it will be placed is 500-600 meters. It is estimated that the 30-meter diameter spheres, which are planned to be produced after the trial studies yield results, will provide a good storage of 20 MWs, and it is possible to make larger diameters if desired. As long as it can withstand the pressure under water and be transported over sea and unloaded with a crane.
Of course, there is also the loss of this kind of mechanical electrical battery, so you get back some of the electricity you give. This is called full circle efficiency and this amount is between 70-80%. Although the loss is seen as a cost, on windy days offshore wind turbines produce more than the countries can consume, in which case the electricity is either wasted or finds a buyer very cheaply. In this case, storing what you can and using it on days when the wind is low is quite ideal, instead of using chemical, flammable, expensive batteries with a lifespan of around 10 years.
This technology is actually quite suitable for countries like us that can reduce concrete costs and reach the deep seas in relatively short distances. Of course, the widespread use of the system will be possible with the widespread use of floating wind turbines. Because the seabed power line to be laid for these turbines will also serve within this storage system.
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