The government will push to drill 5km underground to find deep heat to heat homes and communities without fossil fuels.
A draft policy drawn up by the Department of Climate and Environment says natural heat is around 25C at a depth of 1km across Ireland and can reach 120C at a depth of 5km.
It said exploratory drills were essential to determine the best location, and recommended a regulatory body and licensing system to govern who could drill, extract and use it.
Issues that need to be addressed include obtaining land for drilling, the high cost of exploration projects and the risk that occupants in new developments served by underfloor heating could be at risk of rising prices because only one supplier can operate in their area.
The issues were raised in a draft policy statement on geothermal energy, which will be open for public comment until March 1.
Geothermal energy has limited use in Ireland, mainly for domestic ground source heat pumps, although IKEA in Dublin has a large version.
In these cases, the source is shallow and the ground temperature is about 9°C to 11°C.The heat is captured and then pressurized by a heat pump to raise the temperature, which is then transported around the building.
Larger projects, such as residential developments or district heating schemes in communities, require digging deeper into the surface and where the water flowing through it is warmer.
According to the draft policy: “Ireland’s geothermal potential is not yet fully understood, as more is needed to understand temperatures deep below our surface.
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“Production temperatures in excess of 60 degrees Celsius will enable geothermal district heating without the use of heat pumps.”
Higher temperatures of 80C to 120C are also believed to be available, but the document states that “bore holes of up to 5km may be required at the higher end”.
In addition to heating homes, geothermal energy can also be used in industrial processes, especially where heat is needed for drying.
It also has agricultural uses, such as heating greenhouses or drying ingredients for the food industry.
At the same time, large-scale shallow geothermal energy can be developed where industry requires cooling processes.
The Irish Sustainable Energy Authority is conducting a national heat energy study and found that 38% of all energy consumed in Ireland is used for heating.
Oil, natural gas and solid fuels remain the main sources and must be replaced with carbon-free alternatives to reduce greenhouse gas emissions.
“It is therefore essential to develop a geological data collection programme to encourage geothermal development,” the draft said.
“In particular, the need for a deep drilling and deep geophysics program was recognized to address knowledge gaps.”
The document also raised the prospect of using natural hot springs.There are at least 40 on record, all in the east and south of the country, but only one is being used to any extent – to heat a public swimming pool in Cork Marlow.
It also said that where heat is extracted in the form of groundwater, the water may contain dissolved minerals and metals, such as zinc and lithium, which can be filtered out and have commercial value.
A series of public information sessions will be organised next month.These will give people time to clarify issues before submitting.