Geothermal Energy

Geothermal energy is a resource that is available beneath the surface of the ground which can be used to:

1. Heat our homes

2. Provide cooling in some applications

3. Feed heat into district heating networks

4. Generate power if the geothermal resource is hot enough

5. Provide therapeutic treatment in spas

The following booklet by Action Renewables (Northern Ireland) provides an introduction to geothermal energy utilisation: Action Renewables Home Heating Guide .

Geothermal energy sources can be classified into the following groups:

1. Shallow geothermal - where the available thermal energy resource is usually augmented through the use of a heat pump to provide heating (and / or in some cases cooling). Shallow geothermal energy systems are connected to the ground thermal resource through either closed loop pipe networks (horizontal or vertical) or open loop systems with ground water being reinjected back to the ground or discharged to streams, rivers or the sea.

2. Deep geothermal - where the energy source is usually hot enough to provide a direct source of heat to the end user or a district heating network, or if hotter again, the energy source could generate power through steam driven turbines.

Ireland has an excellent source of shallow geothermal energy reserves. Our shallow groundwaters provide a stable resource of themal energy that can be used to provide heating at very high efficiencies. Through the use of refrigerant based heat pumps, effective returns of 4 to 6kW of heating energy for every 1 kW of electrical energy input can be achieved. Heat pump technology has also progressed to the point where the same systems can heat the hot water for your showers and wash-hand basins.

With the 'greening' of the Irish electricity grid where carbon dioxide emissions have  been reduced, it is clearly a more environmentally responsible way of heating your home. At the same time users will benefit from lower heating costs when compared to oil or LPG fired boilers.

With the onset of 'smart' energy meters, substantial cost savings can be made if most of the heating needs are delivered during 'off-peak' hours when electricity costs are typically halved. To avail of the lower electricity tariffs, your home will need to be able to retain the heat for at least 16 hours, prompting a renewed focus on minimising heat loss through poor insulation levels and 'leaky' building envelopes.

Image source - Geological Survey Ireland 2022