While the search for useable energy continues at a rapid pace in order to satisfy the growing planet's growing population, there remains the need to find energy storage methods that not only supply the appropriate forms of energy to the local communities but will be environmentally compatible with the natural world.
Pumped storage systems are already utilised around the world and the engineering technology that they incorporate is well understood. It is an effecient method of storing potential energy so that it can be released quickly when it is needed during periods of high demand.
A fine large-scale example of such a generating system is the Dinorwig Power Station in North wales, U.K, - at a location sometimes known as 'Electric Mountain'. The water there is pumped up overnight from a lower lake to a former slate quarry that has been converted into a high-level storage reservoir. At times of peak demand, special penstock valves open to allow the system to deliver full power within 75 seconds as the water flows rapidly back down. The disadvantage of this particular system is that, pumping the water back up to the High Head reservoir, the reversible Francis -type turbines that produce the power actually use 33% more energy than they help to generate. Furthermore, that electrical energy has to be obtained from power stations whose operations often produce large amounts of carbon.
Seawater-based pumped storage systems are already being built, having been proved environmentally sound with special impermeable linings that prevent any contamination of the ground. One such system is the fully-operational 30MW Yanbaru plant in Japan, but still relies on the original concept of using reversible generator turbines.
Hales Energy has patents pending on the utilisation of Tidal Stream Turbines in several types of system, thereby adding a renewable energy element to the best aspects of pumped storage technology.
Hales Tidal Stream Turbines (TSTs) can operate effectively in the turbulent coastal waters near to shore.
The first type system would use such turbines to simply pump seawater up to a High Head reservoir throughout the periods of ocean current or tidal flows. After being released through the power-generation process, the water would be discharges back to the sea through a spillway, thus completing a simple open cycle.
Should onshore generation prove too problematic, a second type system would again use such Hales Turbines - but with both the generator and the seawater pump on the same vertical power output shaft.
During periods of HIGH TIDAL FLOW, the TST's would produce direct electrical power when there was High Demand for it but, when there was only Low Demand for it, they would switch automatically to pumping seawater up to the high-level reservoir. However, during periods of LOW TIDAL FLOW but High Demand for power, the pumped-stored seawater would be released from the reservoir and directed down through diffusers into the tidal inlet sides of the Hales Turbines, thereby bringing the system up to full power and maintaining that level of output - with the flow from the reservoir being gradually reduced as the tidal flows itself increased again.
An added bonus of a seawater -based pumped storage system is that the delivery of aerated and nutrient-rich seawater to a high-level reservoir enables forms of aquaculture to be developed in a safe, controlled environment.
In addition, such a system could also be considered as a means of providing fresh water by using the High Head pressure for reverse osmosis.
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