Innovative solutions to the problem of storing energy generated by renewable sources are being developed by researchers at The University of Nottingham.
Academics have received €1.4m (£1.1m) in funding from E.ON, one of Europe's leading power and gas companies, to develop a new generation of super batteries and undersea storage bags that will collect energy in the form of compressed air.
As methods of producing energy from renewable sources such as wind, solar and wave and tidal power become more advanced, the effective and efficient storage of that energy is fast becoming one of the key challenges facing the energy industry. As these types of renewables can only produce energy under favourable conditions, for example when the wind is blowing, storage capacity will help in ensuring supply can be matched to demand.
Dr George Chen in the University's School of Chemical and Environmental Engineering and Dr Christian Klumpner in the School of Electrical and Electronic Engineering are using cutting edge nanotechnology to develop an electrical energy storage system based on power electronics and a new energy storage device called a supercapattery, which combines the benefits of a supercapacitor and a battery. It will be constructed from carbon nanotubes — tiny hollow structures made from carbon atoms — chemically engineered with traditional battery materials.
Dr Chen said: “Electricity generated from renewable sources can be transported instantly through cables over long distances but storage is a problem — if you don't use it, you lose it.
“Our aim is to develop something which will bring together the best of both worlds — the high electrical energy storage capacity of a battery and the fast charge/discharge rates of a supercapacitor.”
On its own a supercapattery would be ideal for powering a portable electrical device, such as a laptop, but the researchers are also investigating the potential of using stacks of supercapatteries which would offer energy storage on a large scale.
Although a supercapattery power bank would initially be expensive to build, it would be both flexible and versatile and could be used to offer the crucial stability needed by the national grid in the event of a national power surge.
“Currently about five per cent of the power of the national grid is standing by in reserve (often thermal) in case of a power surge — for example when everyone puts their kettle on after the football match has finished. To have generators on standby costs a great deal of money, whereas these devices could be called into action at very short notice and provide extra power within a very short timeframe.”
Professor Seamus Garvey in the University's School of Mechanical, Materials and Manufacturing Engineering is looking at using a combination of wind, wave, tidal and solar power to compress and pump air into underwater bags anchored to the seabed. During periods of high demand, the air would be released through a turbine, converting it to electricity.
ICARES — or Integrated Compressed Air Renewable Energy Systems — could see vast offshore energy farms being created off the coastline around the UK.
Professor Garvey said: “At periods of peak demand in the day, the instantaneous value of electrical power can be several times greater than at periods of low demand. Energy storage can enable us to use off-peak energy to meet the demand in peak hours.
“Renewable energy sources provide a green alternative to the thermal generation plant which currently provide the bulk of UK electricity. This technology, if commercially available, could help to increase renewable energy's share in Britain's energy mix as older power stations are taken out of service”
E.ON has a renewable development portfolio in the UK that could produce enough renewable power for around a million homes and displace the emission of almost two million tonnes of carbon dioxide a year. Worldwide, the group plans to invest €6 billion in renewable energy projects by 2010.
In addition, E.ON is also committed to cutting the amount of carbon it produces for every unit of electricity it generates by 10 per cent by 2012, having already reduced it by 20 per cent since 1990. The group is aiming to cut the same figure by 50 per cent by 2030.
Allan Jones, Managing Director of E.ON Engineering, said: “Energy storage will help further the development of renewables.
“It's our duty, more than ever, to reconcile the three goals of reasonable pricing, climate protection and security of supply. If we're to succeed, it's essential not only to improve energy efficiency but, above all, to create an energy mix with the lowest possible share of CO2.”