Getting energy from rocks is, of course, the job description of petroleum geologists, but if a team of researchers at The University of Texas at Austin are successful, it could be the start of a range of applications for those skills in an exciting new industry – that of geologic hydrogen.
“The hydrogen production potential is enormous when you consider the amount of Fe+2 that is available within the upper three kilometers of the Earth’s crust.”
That’s Toti E. Larson, AAPG member and research associate professor at the Bureau of Economic Geology of the Jackson School of Geosciences at the University of Texas, Austin, who, along with his team at UT, have been working on a project that explores a variety of natural catalysts that will produce hydrogen from such basins that are metamorphic or igneous.
Why the excitement?
Producing hydrogen this way emits no carbon dioxide.
It is an enormous undertaking, but Larson said the progress is “extremely encouraging.”
The Concept
The process is known as “serpentinization,” which occurs when rocks such as olivine, a mineral found in igneous rocks, contacts with underground water and rust, captures the oxygen to make iron oxides.
But the hydrogen is left behind.
Producing hydrogen from these “basement rocks” – called that because they are found below a sedimentary platform – is a different process from natural gas reformation, which are associated with organic-matter rich sedimentary basins.
“It is possible we have overlooked hydrogen deposits because we have not looked for it or drilled wells in areas where you would expect high concentrations of hydrogen,” said Larson.
Hydrogen has always been important to the global economy and is used in a wide range of industrial and agricultural applications, including rocket fuel. But, as mentioned, current methods to produce hydrogen use fossil fuels as a source, which has a large carbon footprint.
Much of the potential non-fossil fuel supply is too deeply buried, too far offshore, or in accumulations that are too small to make them economically recoverable, but the thinking is that if even a small fraction of this estimated volume could be accessed economically, there would likely be enough hydrogen across all the global deposits to last for hundreds of years.
That is what Larson is after.
“The key,” he said, “is to understand if hydrogen exists in significant accumulations that can be economically accessed, and if so, how to find these resources.”
The Research
His experiments at UT, conducted in the laboratory in sealed reaction vessels, are trying to ascertain that.
“They are batch experiments where they can closely control the starting materials, which includes mineral assemblages and rock types. For natural catalysts they are working with rocks and minerals that contain inclusions and/or elevated concentrations of catalysts. They then compare reaction progress in catalyst-bearing rocks to those that do not contain catalysts.”
Esti Ukar, his colleague on the project, said they are trying to speed up nature.
“Yes, we are attempting to engineer serpentinization through the use of catalysts,” said Larson, who emphasized that the only gas produced from serpentinization is hydrogen.
“This is part of what makes hydrogen so appealing as a low-carbon source,” he explained.
Larson said, when considering the locations that have the appropriate geological deposits for geologic hydrogen – the Midcontinent Rift System in Kansas, Missouri and Minnesota, for example – the possibilities can significantly diversify the energy portfolio of the United States.
“Finding economic sources of carbon-neutral geologic hydrogen would significantly decrease the carbon footprint of the hydrogen economy and provide a source of a low-carbon fuel and feedstock,” said Larson.
That work is not only being welcomed. It is being noticed.
The Advanced Research Projects Agency–Energy, a U.S. government agency tasked with promoting and funding research and development of advanced energy technologies, has awarded Larson and his team, in collaboration with the University of Wyoming’s School of Energy Resources, a $1.7-million grant.
“The $1.7 million investment from ARPA-E is a sizable investment that will allow us to quantify reaction rates at the laboratory scale, which will put us in an excellent position to better identify regions for hydrogen exploration and identify industrial process that can be used increase the amount of hydrogen available for extraction,” said Larson.
There are many challenges, not the least of which are the many well-controlled experiments that will be needed to be able to identify reaction mechanisms.
“We are in the early stages of this research, but one of the hurdles we had to overcome was in the design of the reaction matrix: Being able to design an experimental platform in the laboratory that can conduct a wide range of experiments under different conditions took a lot of careful planning,” he said.
It has been a slow, but steady process.
“Early in the reaction space we are working with very low concentrations of gases, and we had to design an approach that would allow us to monitor small changes in products,” he added.
Impacts and Challenges
Larson believes the work will not only change the energy landscape, but the energy industry as well.
“The economic production of geologic hydrogen in the subsurface at an industrial scale absolutely is a grand challenge and will require considerable funding and capital to bring online,” he said.
Larson said government subsidies won’t be enough to bring this about, though.
“Of course, the full development of geologic hydrogen will require substantial private equity investment, which we are already seeing,” he said.
The goal is to identify approaches that can stimulate production of hydrogen in the subsurface.
“We are encouraged that this approach does not include carbon dioxide or methane as a product, and that remains one of the primary metrics we are using to evaluate this project. Once taken from the field, the surface footprint of this process is quite small, which will help minimize surface environmental impacts,” he said.
As with all new applications and alternatives in the energy sector, there are questions about whether the industry is willing, able and ready to meet them.
Larson is sanguine.
“The energy industry has a record of adapting to changing energy economies and has considerable experience in engineering solutions to difficult subsurface problems,” he said, alluding to the amount of talent within the energy industry that will be needed to tackle the engineering problems needed to bring the hydrogen economy online.
This is not a matter of choosing one source of energy over any other.
“There are differences of course in oil and gas deposits versus deposits most likely to be successful for geologic hydrogen production. But I have no doubt the energy industry will be able to meet these challenges,” he said.