Contrary to the widespread belief, you don’t need to live beside a volcano with hot rocks on your doorstep to be able to avail of vast quantities of geothermal energy – a year-round source of clean heat – but equally good for cooling.
I used to believe this source of energy was at best niche in the Irish context; that reality trumped the optimism of geologists. The mistaken view took hold that those in the sector, who raved about the technology, were pioneers at the frontier who happened to find a rare pocket of geothermal energy due to a geological quirk in the subterranean landscape. How wrong could you be?
It is clear that the energy dynamics make it a realistic proposition over carbon-intensive and unhealthy fossil fuels; especially when advances in drilling technology and heat pumps are factored in – the geothermal variety rather than air-source. The latter grabs heat from outside air, while the former, which is more efficient, pulls heat from the stable temperature of the Earth, ie is “ground-source”.
So why is geothermal regarded as the sleeping giant of the energy world? The short answer is probably use of “cheap” fossil fuels at the heart of so many economies for many decades and genuine low cost of renewables such as solar and wind. Then there is the high upfront initial investment cost – though over the long term, geothermal can outdo all those options, while overcoming the intermittency of renewables. Wind and solar don’t produce power consistently, fluctuating with weather (sunshine/wind speed) and daily cycles (day/night), creating gaps between energy supply amid constant grid demand.
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There are growing examples of companies in Ireland (such as Ikea and Dublin Airport Authority), industries and institutions pushing on with geothermal or exploring how they can avail of it, although there is a notable absence of government supports and geological data to send the right financial signals with a view to scale-up. It has the potential to be the perfect complement to the roll-out of district heating systems in urban areas.
In fairness, the Geothermal Association of Ireland and the Department of Climate, Environment and Energy are due to unveil new development plans, but in the meantime a government policy statement from 2023 is a signal of intent. A Budget 2026 allocation of €500 million for district heating is a good platform on which to build.
A podcast featuring Dr Aoife Braiden of Research Management & Logistics and Dr Sarah Blake, a senior geologist with Geological Survey Ireland (GSI) who leads GSI’s geothermal energy programme, provides an outline of what can be delivered. They are geothermal champions, epitomised by their support of the Gemini Project, an all-island initiative to showcase what is possible, led by Dublin’s energy agency, Codema.
Ireland can harness “deep heat” for heating and cooling by using the stable, cool temperature of the Earth as a heat sink with good storage options beyond a few hours. It is possible to generate electricity (using steam) but that it is contingent on being able to go deep enough or being close to tectonic plates in the Earth’s crust where heat flows faster – such as in Iceland – so in Ireland’s case this will not be realisable anytime soon.
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But that should not distract from its versatility. In the Paris basin thermal heat from a deep aquifer 2km below the surface is used to heat some 250,000 homes. In Ireland it is estimated that 60-70 degrees at the surface is needed from a reservoir 2km below to fulfil a similar role. Equally, shallow (small-scale) geothermal with a heat pump can heat a house, estate, apartment block or swimming pool emanating from just 200 metres below ground.
The Grangegorman demonstration site being developed by Technological University Dublin under Gemini is an example of deep geothermal with the ability to heat a campus while weaning off gas. It has achieved 38 degrees at 1km so signs are good for a second 2km borehole.
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The technology has obvious – and proven – suitability for use in brewing, cheesemaking and horticulture, not to mention big institutions such as hospitals and, especially, in solving the high heat/energy demands associated with data centres. According to Braiden, there is an obvious absence of key enablers; legislation and regulations from the Government – though that has been promised for early this year. The other critical catalyst is geological data from potential geothermal sites, which GSI has the capacity to provide.
Apart from housing, the lack of available affordable, clean energy, reinforced by security of supply, is a problem persisting across much of Europe. It’s time for geothermal to be added to the solution mix.
Kevin O’Sullivan is an environmental consultant
