| Abstract |
Ireland is impoverished in geothermal energy resources, mainly because it lies outside the sphere of recent Alpine tectonic activity and is distant from plate boundaries. Geothermal gradients in Ireland, based on measurements in deep boreholes, range from 3oC/km to 43oC/km with a mean gradient of 25oC/km. The only recognised geothermal resources within the Irish Republic are 42 documented warm springs in the eastern and southern parts of the country, ranging in temperature from 13-24.7 C, only one of which is exploited. This has been utilised to heat a municipal swimming pool with the assistance of a 100 kW heat pump. The main geothermal energy development in Ireland is space heating, based on ground sourced heat pump technology, mainly at a domestic level but also encompassing smaller public buildings. One other source of geothermal energy currently being developed is a hydrogeothermal source utilising shallow groundwater in gravels beneath urban areas where the urban 'heat island' effect gives rise to slightly enhanced groundwater temperatures. This source, which also employs heat pump technology for space heating has been successfully employed in a small number of projects in Dublin, and is currently being developed in Cork, where it probably has greater potential for exploitation. Heat pumps, using ground or groundwater sources, currently number 1500 and represent Irelands burgeoning utilisation of its low temperature resources. Domestic use is the most significant category, with heat pumps in the 12-14 kW size, but there are approximately 20 large-scale installations operating successfully, ranging in size from 19-200 kW. At the present time, total geothermal energy usage in the form of heat pump capacity is of the order of just under 20 MW, but growth in the heat pump market is strong at 45%. Other potential uses of geothermal energy are under investigation. |