Monday, 22 July, 2024 / Edition 17

Working on Core Elements makes me realize that almost every energy resource is undergoing a technological revolution. Each comes with benefits but also societal and innovation challenges. But these challenges create opportunities—so while reading this edition, think of how geoscientists and engineers can play key roles in the solution.

Rasoul Sorkhabi

Editor, Core Elements

Geologic Hydrogen from Oman

Recent and ongoing projects in Oman aim to characterize and stimulate ophiolite rocks to procure geologic hydrogen at reservoir scale. This stimulation project was launched in 2023. Let’s take a look at the geology behind this project, new developments, and how the technology will work. 

Ophiolite and Serpentinite:

• Ophiolite, meaning “snake-rock” in Greek because of its texture, is an assemblage of mafic and ultramafic rocks originated in the oceanic crust but now outcropped in the continents.

• A related term is serpentinite, also meaning “snake-rock,” but ophiolite is a more general term. Serpentinite is a greenish, soapy-feeling rock derived from an alternation of peridotite.    

Samail Ophiolite: Samail Ophiolite is a Cretaceous-age sliver of the Tethys Oceanic crust outcropped in northern Oman—the largest exposed body of ophiolite rock in the world. It has been studied for decades, but this rock formation has recently received much attention because of its hydrogen potential.  

Hydrogen Formation from Ophiolite: Research articles by Ellison and colleagues (2021), Leong and colleagues (2023), and Templeton and colleagues (2024) discuss how serpentinite in the Samail Ophiolite reacts with groundwater and releases natural hydrogen.

• Ophiolites contain iron-rich minerals, and the reaction of iron with water generates hydrogen.

• Much of this geologic hydrogen is consumed by subsurface microbes, except where the hydrogen is channeled to the surface through faults.

The project is based on work from:

• A 2021 study that demonstrated that the hydrogen formation process in ophiolite rocks interacting with groundwater containing hyperalkaline fluids rich in hydrogen and methane can continue at 50°C.

• Scientists in a 2023 study also measured the outgassing rates of hydrogen in several hyperalkaline spring sites in Oman. The values are variable and range up to 70,000 mol per year.

What’s new: In March, a technoeconomic analysis showed that hydrogen generation rates can increase 10,000 times with stimulation. The chosen stimulation technique must:

• Increase the density of rock fractures, as well as the water-to-rock ratio

• Modify the chemistry of the injected fluids to optimize the formation of iron-bearing secondary phases

• Minimize microbial consumption of hydrogen

How the stimulation works:

• The new Oman project aims to drill wells into rocks and fracture them with electric shocks. 

• The rock formation is then chemically stimulated with water and heat to accelerate the process of hydrogen formation.

• Massachusetts-based Eden GeoPower is taking the lead in developing this stimulation technique in Oman.

Why it matters:

• The pilot project in Oman reported in New Scientist will demonstrate the success and hurdles of this cutting-edge technology and how it can be improved and implemented. 

• Geologic hydrogen from iron-rich geologic terrains occurs in many parts of the world. Recall that serpentinite is the state rock of California. So, if this project goes well, it could be applied in many other locations worldwide.

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Lithium from Brazil’s Minas Gerais

 Vitalii Stock/ Shutterstock.com

Lithium, crowned as “white gold” because of the massive demand for its use in batteries, can be extracted from hard rocks or from brines.

In the 1st and 14th Editions of Core Elements, we looked at issues related to lithium mining from brines in Argentina. A new article looks into lithium production from hard rocks in Brazil.

Hard rock mining consumes much less water than evaporative mining from salt brines. Nevertheless, a recent article in New Humanist reports on tensions between indigenous communities and mining companies in Brazil.

Minas Gerias:

• Brazil’s fourth-largest state by area and the second-largest by population, Minas Gerais (“General Mines”), has a mining history that dates back to the 18th century.

• The Jequitinhonha Valley is home to the mineral spodumene, a highly valuable and pure source of lithium.

• Spodumene is a pyroxene mineral with the chemical composition LiAl(SiO3)2.

• Lithium production from the Jequitinhonha Valley is 45,000 metric tons a year.

Who’s involved:

• Privately-owned Brazilian Lithium Company (CBL) has mined in the valley since the early 1990s, but several other companies are joining the game.

• Canada’s Sigma Lithium entered the area in 2023.

• Other companies expected to follow are Florida-based Atlas Lithium, AMG Brasil, Latin Resources, and Lithium Ionic.

What they are saying: Political leaders, such as the governor of Minas Gerais, have welcomed foreign investors, arguing that the Jequitinhonha Valley used to be called the “valley of misery” because of its poverty, but thanks to mining, it is now a “valley of opportunity.”

This is partially true, especially if we consider that formerly sleepy towns are now booming and bustling with construction, new hotels, and restaurants.

Indigenous people: But native peoples living in the valley have a different perspective. The Quilombo (“war camp”) community is a group of African ethnicities who escaped slavery and settled in this part of Brazil in the 17th century. Activists from this community mention problems such as daily detonations, dust clouds, and hazards to wildlife and water resources.

What to watch: How can society work to address the need for battery materials with respect for indigenous communities?

Go deeper: Read the full article in New Humanist here.

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✉️ To get in touch with Rasoul, send an email to editorial@aapg.org.