This Flywheel Renewable Energy Storage plant being built in Ireland could solve the problem of clean energy supply shortfalls when there is insufficient sun or wind. The storage will be unlimited.
The plant will use a motor-generated flywheel to harness kinetic energy from the grid at times of over-supply. This will then be released from submerged turbines at times of supply shortfalls.
The project in Rhode, County Offaly, is expected to launch commercially in 2017, with an operating capacity of 20MW.
Unlike conventional coal and gas generators which have an efficiency ratio of 35-40%, the flywheel operates at upwards of 85-90% efficiency.
In flywheel plants, advanced carbon fibre tubes up to 3m high and 1m wide are floated on magnets inside a vacuum, and spun by electricity in a near frictionless environment, until power is needed back in the grid.
Co-designers, professor Noel Buckley of the University of Limerick said that it would be able to match variable renewable energy supplies to consumer demand, whenever it arose.
The grid is designed to run at 50 hertz and when there is an imbalance between supply and demand, the frequency starts to change. By using back-up flow batteries which store electricity in tanks in a liquid form, you can scale up your power and storage capacities separately so that, in principle, the storage can be unlimited.