Newly funded research will explore the use of natural catalysts to kickstart hydrogen gas production from iron-rich rocks. Should tests show success, they could lay out steps to accelerate the carbon-cutting commercialisation of geological hydrogen, by artificially creating it in the subsurface.

Hydrogen presents opportunities as it is clean burning and there is existing demand
Natural hydrogen has gained interest but scientists are working on ways to emulate this via chemistry
R&D is a risky business. But with government support, options such as serpentisation and microbial may yet play a role in the clean energy shift

There is growing interest around hydrogen in the energy industry as a clean fuel source that could decarbonise industry.

Amid the talk of hydrogen as a transition fuel, the emphasis has been on electrolysis or steam methane reforming. Natural hydrogen, sometimes referred to as gold or white hydrogen, has been hitting the headlines as an alternative, natural source of hydrogen that is nearly entirely clean. Artificial generation of hydrogen may just trump it.

New grants from the US Department of Energy were recently announced. These will test the viability of different artificial methods of natural hydrogen production. One such project with potential involves using catalysts to generate natural hydrogen from iron-rich rocks in the US.

Natural to artificial?

Natural hydrogen forms in the subsurface over millions of years. A number of companies have cropped up to search for this resource across the world. Companies have been working in Australia, South Korea, France and Canada and they tend to be exploration start-ups.

According to Rystad Energy research, 40 companies at the end of 2023 were searching for natural hydrogen deposits. In 2020, there were 10.

Should finds be commercial, white hydrogen may well have a cost advantage. Estimates suggest it may cost from $0.5 to $1 per kg.

Grey hydrogen, meanwhile, costs just under $2 per kg, while green hydrogen is around three times as expensive.

Natural hydrogen also has a low carbon intensity and is a clean fuel. There is one main obstacle – the volume of reserves accessible.

Rystad Energy head of hydrogen research Minh Khoi Le said there was uncertainty around natural hydrogen. However, it “has the potential to be a gamechanger for the clean hydrogen sector as an affordable, clean natural resource, thereby shifting the role of hydrogen from an energy carrier to part of the primary energy supply”.

The official went on to say the size of reserves “is still unclear”. Furthermore, “the transportation and distribution challenges of hydrogen remain”.

Artificially generating hydrogen could overcome this uncertainty around finding sufficient reserves. This depends on understanding how hydrogen is formed in the first place and then completing reliable tests.

Cracking the code

Even to geologists, there is some debate around the creation of natural hydrogen. The most common theory is serpentisation, which provides an analogue to scientists who want to simulate hydrogen from rocks artificially.

Researchers Esti Ukar and Toti E Larson from The University of Austin at Texas’ Bureau of Economic Geology have completed initial lab tests. These show that, applying chemical catalysts to iron-rich rocks can kick start a reaction – and produce hydrogen.

Serpentisation usually happens at high temperatures. Natural catalysts such as nickel and platinum can help stimulate hydrogen production at lower temperatures and depths.

In addition, their catalyst-based reactions could speed up what would normally take millions of years to occur in nature.

Next, they will need to move from a small-scale batch reactor. They will need to apply this technology to larger-scale core flood tests for a range of rock types. This should provide insights to understand where in the US this method is most effectively applied.

The US Department of Energy has provided $1.7 million of funding, via ARPA-E, to scale up the tests. The aim is to see how the approach performs in the “real world” of complex geology.

Seeking locations

Combining geochemistry, geology, machine learning and subsurface modelling, this research will help to pinpoint the temperature and fluid conditions.

The researchers will collaborate with scientists at the University of Wyoming’s School of Energy Resources. The focus will be on how feasible the process is on different types of rocks. This may range from banded iron formations in Wyoming, to mafic basalts in the Midcontinent Rift system.

This is one of several natural hydrogen experiments backed by ARPA-E. Others include a focus on Enhanced Hydrogen Production (EHP) and the role of self-propagating fractures.

“With funding from ARPA-E, project teams from across the nation will explore the possibility of accelerating the production and extraction of natural hydrogen,” Evelyn Wang, the agency’s director, said in a statement.

This will transform “our understanding of this critical energy resource”, Wang said. The aim is to accelerate “while accelerating “solutions we need to lower energy costs and increase our nation’s energy security”.

The $20mn fund is divided across multiple projects exploring ways of triggering the generation and production of natural hydrogen.

Theory to practice

Research must take into account uncertainties from lab tests and computer models. There is a danger in over-simplification if they are to be translated to a larger, more complex geological context.

The researchers told E-FWD that their work focuses on laboratory work, with an evaluation of conditions and rock types.

“Upscaling our benchtop experiments to a successful field test will require an understanding of geological heterogeneities, and how that heterogeneity will affect hydrogen production from rocks,” where heterogeneity broadly relates to the degree of variation of geological features.

The crucial test will be whether the catalysts can produce hydrogen from iron-rich rocks at lower than the usual required temperature and depth. Inevitably, it will require further research.

Pete Johnson, co-founder of Koloma, is also working on the microbial activity involved in hydrogen stimulation.

Johnson spoke to the Senate Committee on Energy and Natural Resources about the resource. Noting that, starting from a position of scepticism, he said it had “seemed too good to be true”.

Following some work, Johnson started to believe. “It became clear to me that the science of hydrogen formation in the subsurface was real. A natural chemical reaction occurs when water contacts iron-rich rock below the surface of the earth and hydrogen is produced.”

Commercial viability

The commercial viability of natural hydrogen is also being questioned. Even if it is possible to stimulate the production of hydrogen in subsurface layers, the output may not be commercially viable. Thus, it is all the more important that the ARPA-E funded tests move ahead.

If the reactions work, a risk remains that not enough will be produced to be economic. Understanding how to control these hydrogen-producing geochemical reactions may unlock a new avenue of energy production.

Research will have to reveal what types of rocks will produce at desirable rates.

Practically, it could involve bringing high-pressure into these iron-rich layers. Researchers must work out even stimulation system at this early stage.

Natural hydrogen may have a part to play, as may artificially catalysed natural hydrogen. Research is at an early stage but it is clear the US policy environment is conducive to such pioneering work.

There is more to be done on the opportunities of natural hydrogen and its part in a clean energy future. To make progress, companies and the government must keep up their R&D progress.

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