| Abstract |
Geothermal energy exploitation in Ireland has expanded rapidly over the last few years, despite low geothermal gradients (<25oC/km) and limited geothermal resources. Emphasis is on exploitation of low temperature resources for space heating, employing heat pump technology, but a major new development is the first deep drilling project to source warmer water at depth for district heating projects, with a trial well drilled to over 1.3 km in the western suburbs of Dublin. There has been a huge increase in the number of heat pump units installed in Ireland, since the last update in 2004, which now stands at approximately 9500 units. Take up has been mainly in the domestic market, with most heat pumps approximately 15 kW in size, but the number of larger scale installations ranging from about 100-450 kW servicing public buildings and institutional/commercial premises is increasing rapidly, and a few even larger developments have been recently installed or are in progress. Recently completed, a 3 MW open loop system at the Athlone City Centre Retail Complex is the largest individual geothermal space heating project in the country. Most domestic systems employ horizontal closed loop collectors, with the more expensive vertical closed loop collector systems mainly employed in urban areas where space is at a premium. Open loop collectors are less popular in the domestic market but preferred for larger systems, particularly in areas underlain by shallow gravel and karst aquifers, and enhanced in urban situations by slightly magnified groundwater temperatures due to the ‘heat island’ effect. A few projects have also employed open loop systems exploiting surface water sources such as ponds and reservoirs, where these exist. Current total geothermal energy usage in the form of heat pump capacity is estimated at 164 MW. The rapid take up of heat pumps in the domestic market has largely resulted from the introduction from 2006 of various government grant schemes for renewables including GHP’s to provide incentives to individual householders and developers to incorporate geothermal and other renewable energy systems into new or existing buildings. Another important recent government initiative has been a wide ranging consultation process with geothermal stakeholders as the initial step in bringing in regulatory controls to guide the development of geothermal energy in Ireland, and Ireland is also involved in the GTR-H project to standardize geothermal regulations throughout the EU. A further significant development is the initiation by Irish higher level institutions of new undergraduate and graduate degree programs in energy engineering, with geothermal energy and heat pump technology part of the curricula. |