UNTAPPED coal seams which could supply the entire energy needs of Swansea for the next 30 years are to be investigated deep under Swansea Bay.

A British/US company has been given permission by the UK Coal Authority to use the very latest techniques in offshore drilling technology to probe beneath the waves.

Clean Coal Ltd will investigate the potential for the underground gasification of the coal seams to produce a gas that can be used in electricity power generation, heating and fuel.

If the investigations over the next 12-18 months prove to be successful, the gasification of the coal reserves and associated infrastructure would, according to the company, provide Wales and the whole of the UK with a significant new and long-term energy supply.

"Studies undertaken by Clean Coal Ltd indicate that the coal reserves in this licence area suitable for underground gasification (estimated to be around 200 million tonnes) could produce the entire energy requirement of Swansea for at least thirty years," said a company spokesman.

"This would be the first time that gasification of underground coal has featured in the UK energy market."

Clean Coal specialises in underground coal gasification and is developing projects in other parts of the world.

It has identified Swansea Bay and four other offshore sites in England and Scotland to be surveyed in order to establish their suitability and energy potential.

The offshore underground investigations in Swansea Bay will include seismic and borehole surveys of an area of nearly 80km² at depths of between 800 and 1200 metres.

The surveys will not have any detrimental impact on the marine life, shipping nor other users of Swansea Bay, according to Clean Coal.

Rohan Courtney, chairman of Clean Coal, said: "Recent developments in directional drilling technology and the growing need for new, secure and environmentally benign sources of energy means that underground coal gasification now merits serious investigation.

"This is an exciting and commercially viable development which can bring significant long-term benefit to South Wales.

"We plan to start our investigations in the first half of next year and will be hosting a public exhibition before we start our work. With the work being carried out deep below the surface, our work should largely go unnoticed but we are keen to share our plans beforehand, explain the process of underground coal gasification and outline the potential benefits to the local economy. It's an exciting development."

Underground coal gasification (UCG) is a method of converting deep seam coals into a combustible gas used for power generation, industrial heating, or the manufacture of hydrogen, syngas, chemical feedstocks, jet fuel or diesel fuel.

The gasification of coal in-situ is achieved by drilling boreholes into the coal and injecting water/air or water/oxygen mixtures.

The other underground sites being investigated are Canonbie in Dumfrieshire, Cromer in Norfolk, Humberside and Sunderland.