Engineering news
New solutions are needed – and, according to the International Energy Agency (IEA), a prime candidate could be found deep underground.
Geothermal energy could meet 15% of the growth in electricity demand between now and 2050 if project costs continue to decline, IEA said last week (13 December) in “The Future of Geothermal Energy”.
This huge contribution could be made possible by new technologies opening up the “massive potential” of geothermal power, the agency said. Existing drilling techniques and equipment currently used in the oil and gas industry could also allow projects to dig deeper beneath the surface, tapping in to “vast low-emissions energy resources”.
Conventional geothermal systems only penetrate to a maximum of 3km, where they access hot, permeable rocks and fluid that transports heat to the surface. These requirements mean their installation is typically limited to areas with volcanoes or hot springs. Countries leading deployment of these systems include the US, Iceland, Indonesia, Türkiye, Kenya and Italy.
New Enhanced Geothermal Systems (EGS) could go much deeper, accessing impermeable rocks 20km underground. At those depths, geothermal energy could be tapped around the world, with temperatures of 300-500ºC. Those conditions can be found at such depths around the world, so “nearly all countries” could benefit, according to the IEA.
Meeting 15% of the growth in demand would involve deployment of up to 800GW of capacity worldwide, the agency said, delivering annual output equivalent to the current electricity demand of the US and India combined.
“New technologies are opening new horizons for geothermal energy across the globe, offering the possibility of meeting a significant portion of the world’s rapidly growing demand for electricity securely and cleanly,” said IEA executive director Fatih Birol.
“What’s more, geothermal is a major opportunity to draw on the technology and expertise of the oil and gas industry. Our analysis shows that the growth of geothermal could generate investment worth $1 trillion by 2035.”
Massachusetts firm Quaise Energy is one of several companies developing EGS, as covered in Professional Engineering earlier this year. The company plans to use ‘millimetre wave drilling’, directing concentrated beams of microwave energy to melt and even vapourise rock. Steam generated from injected water could then power turbines in defunct brownfield power stations, the company hopes, providing easily exportable renewable electricity.
Reusing fossil fuel infrastructure to generate electricity will be a “win-win situation” for everyone involved, claimed Quaise co-founder Matt Houde. “The power plant operator is able to keep their plants operating, workers are able to retain the jobs without burning of coal or any sort of fossil fuel, whereas we have an ideal site,” he said.
The IEA called for “clear, long-term regulatory visibility” for investors to improve the cost competitiveness of geothermal projects. By doing so, the report finds that costs could fall by 80% by 2035, to about $50 per megawatt hour (MWh). This would make geothermal the cheapest source of dispatchable low-emissions electricity, on a par with existing hydropower and nuclear installations. At those price levels, geothermal would also be highly competitive with solar PV and wind paired with battery storage.
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