Thursday, March 10, 2016
Victoria's Green Matters - 10th March 2016
We have had ‘hydroelectric pumped storage’ systems in the UK for a long time where water is held in a lake at the top of a mountain. When there is a high demand for electricity from the National Grid, the water is released to drive turbines situated at the foot of the mountain and the resulting electricity is fed into the grid. When demand is low, the water is pumped back up to the lake until the next time it is required. We have four of these sites around the UK but the big disadvantage is that a mountain is required!
A new system that is due to come into operation this month is called ‘compressed air energy storage’. This uses off peak electricity to compress air into an underground cavern. When electricity is needed, the high pressure gas is released to turn a turbine and the electricity produced delivered to the grid. The benefit of this system is that it can be sited where it is needed – the first one is in Manchester.
The UK’s largest energy storage system is an £18 million plant in Leighton Buzzard. This is a 6 MW lithium ion battery installation which supplies power to the town and balances power to the grid, for which the company earns money. There is also a 10MW lithium ion installation in Northern Ireland while the Scottish island of Gigha has a 1.68 MW vanadium flow battery system which supports the island’s wind turbines and a limited grid connection from an aging sea cable.
What is of more interest to people who generate their own electricity from solar roof panels is the possibility of storing the energy generated for use when the sun is not shining. The ‘home battery system’ is a briefcase sized lithium ion battery, costing about £2,000 which can store surplus energy from solar panels and can also earn money as part of a smart network of home batteries which can help balance the National Grid. Much criticism is levelled at renewable energy systems because they are reliant on natural phenomena which are not always available. With the development of these various storage systems, energy will be available on demand.