Credit: Alexander Richter

One hurdle standing in the way of a transition to renewable energy is the increased need for mining that these technologies bring. Now, Oxford researchers are looking at a novel method for extracting precious metals from boiling brines under volcanoes, with the added benefit of generating geothermal electricity.

Drill cores collected in Japan, Italy, Montserrat, Indonesia, and Mexico provided the scientists with further evidence that these metal-rich brines do indeed occur beneath volcanoes. They draw the conclusion that such deposits are probably present beneath practically all active and dormant volcanoes worldwide, constituting a sizable undiscovered gold mine.

The possibility exists that the drilling activities might cause volcanic outbursts, albeit improbably. Although the Oxford claims it is improbable given that they would be drilling above the magma chambers, the danger must still be considered. According to the researchers, they have spent the previous five years assessing and reducing the hazards associated with the procedure and are now prepared to locate a site for drilling the first exploratory well.

Despite how intriguing the idea is, it’s still extremely early. The team at Oxford estimates that it may take five to fifteen years until a functioning volcanic brine mine is operational.

One of the reasons for this is that for brine mining as well as geothermal power, it can be difficult to get liquids to flow into rocks at extreme temperatures. Rocks operate in a ductile rather than brittle manner at high temperatures inside the Earth, which prevents fracture development and lowers permeability. Reservoir stimulation, a procedure at the core of improved geothermal systems, is one remedy for this issue. This strategy generally involves infusing liquids into the reservoir at rates too low to cause seismicity, but enough to encourage the formation of cracks and permeability. Fortunately, new research from Japan demonstrates how activated ductile reservoirs typically generate ‘cloud-fracture networks’ made up of a large number of microscopic, permeability-enhancing microcracks as opposed to big, fault-like fractures. It remains to be seen if dense brines can be retrieved in this manner along with less dense supercritical fluids.

A special point of view

Energy and metal demand cannot be eliminated since they have always been essential for economies to grow and flourish. To demonise mining while enjoying the financial gains it brings would be hypocritical. And yet, this is frequently the case, in part because metal mining and consumption are typically spatially unconnected. This is a relic of the Industrial Revolution and colonial eras in many respects. It is important to recognise the connection between resources and their supply chain, as with so much of what we consume.

We suggest that mining metals unconventionally, which has a lower impact on the environment and may even be carbon-zero, might be one method to address the quickly developing energy dilemma. Magmatic brines may be able to change the current resource paradigm, as is becoming more widely recognised. The key to determining how we might simultaneously capture geothermal power and metals, and therefore better prepare us for the energy shift, is to invest time in technical research and increase our comprehension of volcanic structures, including drilling into them. Since magmatic fluid storage in subsurface porous rock is similar to that in oil and gas reservoirs, current hydrocarbon expertise might be easily used to the search for brine reserves.

It’s critical to continue the de-risking work, which Oxford are doing through a global partnership, according to Joe Blundy from Geoscientist. Similarly, they must choose the ideal test-case volcano before drilling an exploratory well.

Oxford scientists as well as other scientists have a distinctive viewpoint that enables us to solve the crucial resource concerns that lie ahead. This includes developing cleaner and more effective extraction and refinement processes as well as improved resource-finding strategies. It also involves enhancing Europe’s resilience to the supply chain’s constant change while taking into account shared worldwide goals to deliver carbon-negative energy.

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