EXPERT OPINION
Ed Ansett , Founder and Chairman , i 3 Solutions Group
cycle is stored using Thermal Energy Storage ( TES ), while the air is pressed into underground caverns . When the stored energy is needed , this compressed air is used to generate power in a turbine while simultaneously recovering the heat from the thermal storage .
4 . Pumped hydro
Pumped-Storage Hydropower ( PSH ) is classified as a hydroelectric energy storage that is configured with two water reservoirs at different elevations which generates power as water passes through a turbine and draws power from the water pumps recharge to the upper reservoir .
PHS are characterised by two different capabilities , the first is an open loop connected to ongoing hydrologic connection to a lake and the second is where two reservoirs are separated from an outside water body .
According to the US Government Office of Energy Efficiency and Renewable Energy : ‘ Pumped-storage currently accounts for 95 % of all utility-scale energy storage in the United States ’.
5 . Tidal current
This renewable energy source is powered by the natural tidal activity of the ocean tides and currents . The movement is a type of kinetic energy , and the tidal power surrounds gravitational hydropower that uses water movement to push a turbine and generate electricity . The submerged turbines are a similar design to miniature wind turbines .
Vortices , whirlpools and eddies are common occurrences on almost every global coastline and are predictable and powerful movements . Tidal data centre projects under development include SIMEC Atlantis Energy ambition for a facility in Caithness , Scotland , powered by 80MW of tidal power . Other projects are proposed for construction near the shoreline in locations such as Atlantis Singapore , Hammerfest Strom Norway , MCT Northern Ireland and Open Hydro Orkney Islands .
6 . Gravity storage
A gravity storage scheme involves a piston with millions of metric tons raised by water pressure to store energy . As the piston descends , this pushes water through a generator to deliver electricity .
Prototype gravity storage projects are being developed by firms such as Scotland-based Gravitricity . It is building a prototype 250kW gravity power unit using towers . It says its units could deliver peak power outputs of between 1 and 20 MW , function for up to 50 years with no loss of performance and deliver full power in under one second .
At the other end of the scale , gravity storage concepts are based on the hydraulic lifting of a large rock mass using water pumps . The rock mass acquires potential energy and can release this energy when the water that is under pressure is discharged back through a turbine .
According to Heindl Energy , gravity storage ; a rock mass with a diameter of 250m , would result in a storage capacity of 8 GWh , which is comparable to the largest pumped storage power station in Goldisthal , Germany ( 8.4 GWh ). It says gravity storage of this type is a concept with which unprecedentedly large quantities of power can be stored over long periods . The capacity of energy storage can be between 1 and 10 GWh , comparable to large pumped hydro storage . ◊
TODAY , IN DATA CENTRES ACROSS THE WORLD , TENS OF THOUSANDS OF FLYWHEELS ARE USED FOR SHORT- TERM ENERGY BACKUP POWER .
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