Under the Lee valley in Co Cork lies another valley. It is known in geological terms as a hidden valley and it contains sufficient resources to heat any new buildings built in Cork city. It is a renewable energy supply just waiting to be tapped.
The hidden valley dates back to the Ice Age when the glaciers ploughed out a cut in the landscape. The phenomenon occurred in many other parts of Ireland as well. When the ice retreated, sea levels rose and with them, rivers, so that the course of the Lee in the valley today runs over the original one formed some 15,000 years ago.
But the difference is that the water under the Lee and under the city is several degrees warmer than water available from the normal groundwater sources.
This is due to its depth in the earth and the warming effect of the city environment which it soaks up and stores. The water is free and renewable, non-polluting and environmentally friendly with major advantages in terms of its practical application.
Dr Alistair Allen of the Geology Department at UCC has been conducting trial bores to establish the extent of the hidden valley and demonstrate that there are vast geothermal resources available.
One test was conducted near City Hall, another at UCC and a third at County Hall. In each case, courtesy of the Ice Age, the sand and gravel bed lining the valley and containing the precious water resource, was discovered at a depth of less than 10 metres. The temperature of normal groundwater in Ireland is between nine and 11 degrees while the temperature of hidden valley water is up to four degrees higher.
Given that almost all of Cork is built over the Ice Age valley, any new buildings could be designed quite easily so as to avail of a reliable and cheap source of heat. Existing buildings could also be adapted but this would be a more costly prospect involving new plumbing arrangements.
Ireland, says Dr Allen, is not blessed with an abundance of natural energy resources. There are peatlands and natural gas off Kinsale as well as the prospect of oil or gas off the west coast - but these are finite commodities and cause pollution when turned to human use.
Geothermal water deposits, on the other hand, would be relatively cheap to harness, their benefits would be lasting and they would have not just one but three practical applications.
As well as heating new buildings, hidden valley water could be used as process water for flushing toilets, for instance. At present, and at considerable cost, available water is treated before being pumped into offices and homes. Much of it is simply flushed down the loo. This, he says, is an expensive and wasteful use of a precious resource and one that is becoming increasingly scarce.
In a third application, after the natural heat is extracted, the geothermal water could be used as part of the refrigeration process, again saving potable water and expense. Supplies to new office buildings and homes would be established at the early phase of construction by simply boring down to the permeable sand and gravel lining of the hidden valley and building on top of the deposit. Cork, Dr Allen, adds, is a rich source of geothermal water and it makes sense to tap into it.
There are instances where geothermal water makes its own way to the surface through faults in the earth's crust. In Ireland, we have some 29 such warm springs, mostly in the south Leinster/Munster area. The majority of them are in isolated locations and have not been exploited as they might be.
One exception is Mallow, Co Cork, where the naturally occurring warm water is used to heat the municipal swimming pool. Typically, these springs range in temperature from 13 to 22 degrees. While the cost of heating will continue to be a significant factor in building design, in the not too distant future security of energy supplies may become just as important, Dr Allen says.
The indications are that climate change will bring more rainfall to Ireland, so there will be warm water in the hidden valleys for as long as we wish to use it.
UCC plans to heat its new art museum on campus using the deposits and it is hoped the new Environmental Research Institute at Ringaskiddy, in Cork Harbour, which is to be a "green building", will be heated from hidden valley resources. New thinking will be required but the prospects "are very exciting", Dr Allen adds.