Power system offers bags of energy

A new spin-out company from Nottingham University aims to prove that a new form of green energy could be in widespread use within 15 years and at a fraction of the cost of its nearest competitor.

Nimrod Energy has been launched by Prof Seamus Garvey to further the development of the Integrated Compressed Air Renewable Energy Systems (ICARES), which he has been involved with since early 2006.

The technology is centred on a simple premise – using giant wind turbines to compress and pump air into huge undersea Energy Bags anchored to the seabed – or geological formations where deep water is not available.

The high-pressure air would then be expanded in special turbo-generator sets to provide electricity as required – not just when the wind is blowing. It would see vast floating offshore ’energy farms’ created off the coastline around the UK.

Over the past year, Prof Garvey’s research has proven that by using huge offshore wind turbines, the total amount of structural material per kW of rated power can be slashed, effectively cutting costs by a factor of four or more. He believes it is possible to store energy at costs well below £10,000/MWh – less than 20 per cent of pumped hydro energy, the cheapest competing technology.

Funded with €310,000 (£277,000) from the E.ON International Research Initiative, Prof Garvey has already developed the Energy Bags and will prototype test them in seawater with the aim of having a storage product ready for use in energy systems by May 2011.

Prof Garvey said that although he had demonstrated the energy-storage system can work, he has not yet built a 230m diameter turbine to provide the air for it. Nevertheless, he predicts that at least 25 per cent of offshore wind power in the UK will use the integrated compressed air approach by 2025.

’Although I expect that the direct-generating wind turbines will catch up with us on cost per unit power output, the role for systems which put energy directly into store is clear. If you have 1MW of integrated compressed air system for every 3MW of conventional generation, then the whole set of offshore wind equipment starts to look like a very versatile power-generating system that can adjust its output to match demand – notwithstanding what the wind is doing,’ he said.