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New Energy World
New Energy World embraces the whole energy industry as it connects and converges to address the decarbonisation challenge. It covers progress being made across the industry, from the dynamics under way to reduce emissions in oil and gas, through improvements to the efficiency of energy conversion and use, to cutting-edge initiatives in renewable and low carbon technologies.
Underground heating: a review of deep geothermal energy
26/6/2024
8 min read
Feature
Geothermal energy’s ability to make a positive contribution to the global energy mix has long been recognised. Unlike solar, it can be used to generate electricity at any time of the day or night. Unlike wind or wave power, its output is also constant. Around 88 countries worldwide are estimated to be using this renewable energy source currently, reports Nnamdi Anyadike.
Despite much interest, gothermal energy remains largely untapped and its current contribution to the global power mix capacity is limited to just 1%. Much of the limitation is to do with the lack of suitable sub-surface locations that can be accessed using current technology. There is also the not-insubstantial risk of seismic activity being triggered. Finally, there are the costs, which the International Renewable Energy Agency (IRENA) says can be considerable. Indeed, the Agency estimates geothermal energy to be the ‘second most expensive renewable energy source’ to install, behind concentrated solar power, although there is the caveat that once installed operation and maintenance costs tend to be very low.
Good news though is on the horizon. Enhanced geothermal technologies that can provide ‘deep geothermal’ renewable energy are now coming onstream. These will allow geothermal energy extraction to take place on a much larger scale and bypass current sub-surface restrictions.
Essentially, these technologies involve two techniques: hydraulic fracturing (fracking) and underground storage; and non-mechanical drilling. Fracking is already widely used in the US oil and gas industry to increase the permeability of rock formations. But with new and advanced drilling techniques, much further penetration of solid underground rock is now possible. This also can involve injecting water deep into the ground to create the steam to drive turbines for power generation.