It's commonly thought that the most abundant element in the universe, hydrogen, exists mainly alongside other elements - with oxygen in water, for example, and with carbon in methane. But naturally occurring underground pockets of pure hydrogen are punching holes in that notion - and generating attention as a potentially unlimited source of carbon-free power.
One interested party is the U.S. Department of Energy, which last month awarded $20 million in research grants to 18 teams from laboratories, universities, and private companies to develop technologies that can lead to cheap, clean fuel from the subsurface.
Geologic hydrogen, as it's known, is produced when water reacts with iron-rich rocks, causing the iron to oxidize. One of the grant recipients, MIT Assistant Professor Iwnetim Abate's research group, will use its $1.3 million grant to determine the ideal conditions for producing hydrogen underground - considering factors such as catalysts to initiate the chemical reaction, temperature, pressure, and pH levels. The goal is to improve efficiency for large-scale production, meeting global energy needs at a competitive cost.
The U.S. Geological Survey estimates there are potentially billions of tons of geologic hydrogen buried in the Earth's crust. Accumulations have been discovered worldwide, and a slew of startups are searching for extractable deposits. Abate is looking to jump-start the natural hydrogen production process, implementing "proactive" approaches that involve stimulating production and harvesting the gas.
"We aim to optimize the reaction parameters to make the reaction faster and produce hydrogen in an economically feasible manner," says Abate, the Chipman Development Professor in the Department of Materials Science and Engineering (DMSE). Abate's research centers on designing materials and technologies for the renewable energy transition, including next-generation batteries and novel chemical methods for energy storage.
Sparking innovation
Interest in geologic hydrogen is growing at a time when governments worldwide are seeking carbon-free energy alternatives to oil and gas. In December, French President Emmanuel Macron said his government would provide funding to explore natural hydrogen. And in February, government and private sector witnesses briefed U.S. lawmakers on opportunities to extract hydrogen from the ground.
Today commercial hydrogen is manufactured at $2 a kilogram, mostly for fertilizer and chemical and steel production, but most methods involve burning fossil fuels, which release Earth-heating carbon. "Green hydrogen," produced with renewable energy, is promising, but at $7 per kilogram, it's expensive.
"If you get hydrogen at a dollar a kilo, it's competitive with natural gas on an energy-price basis," says Douglas Wicks, a program director at Advanced Research Projects Agency - Energy (ARPA-E), the Department of Energy organization leading the geologic hydrogen grant program.
Recipients of the ARPA-E grants include Colorado School of Mines, Texas Tech University, and Los Alamos National Laboratory, plus private companies including Koloma, a hydrogen production startup that has received funding from Amazon and Bill Gates. The projects themselves are diverse, ranging from applying industrial oil and gas methods for hydrogen production and extraction to developing models to understand hydrogen formation in rocks. The purpose: to address questions in what Wicks calls a "total white space."
"In geologic hydrogen, we don't know how we can accelerate the production of it, because it's a chemical reaction, nor do we really understand how to engineer the subsurface so that we can safely extract it," Wicks says. "We're trying to bring in the best skills of each of the different groups to work on this under the idea that the ensemble should be able to give us good answers in a fairly rapid timeframe."
Geochemist Viacheslav Zgonnik, one of the foremost experts in the natural hydrogen field, agrees that the list of unknowns is long, as is the road to the first commercial projects. But he says efforts to stimulate hydrogen production - to harness the natural reaction between water and rock - present "tremendous potential."
"The idea is to find ways we can accelerate that reaction and control it so we can produce hydrogen on demand in specific places," says Zgonnik, CEO and founder of Natural Hydrogen Energy, a Denver-based startup that has mineral leases for exploratory drilling in the United States. "If we can achieve that goal, it means that we can potentially replace fossil fuels with stimulated hydrogen."
"A full-circle moment"
For Abate, the connection to the project is personal. As a child in his hometown in Ethiopia, power outages were a usual occurrence - the lights would be out three, maybe four days a week. Flickering candles or pollutant-emitting kerosene lamps were often the only source of light for doing homework at night.
"And for the household, we had to use wood and charcoal for chores such as cooking," says Abate. "That was my story all the way until the end of high school and before I came to the U.S. for college."
In 1987, well-diggers drilling for water in Mali in Western Africa uncovered a natural hydrogen deposit, causing an explosion. Decades later, Malian entrepreneur Aliou Diallo and his Canadian oil and gas company tapped the well and used an engine to burn hydrogen and power electricity in the nearby village.
Ditching oil and gas, Diallo launched Hydroma, the world's first hydrogen exploration enterprise. The company is drilling wells near the original site that have yielded high concentrations of the gas.
"So, what used to be known as an energy-poor continent now is generating hope for the future of the world," Abate says. "Learning about that was a full-circle moment for me. Of course, the problem is global; the solution is global. But then the connection with my personal journey, plus the solution coming from my home continent, makes me personally connected to the problem and to the solution."
Experiments that scale
Abate and researchers in his lab are formulating a recipe for a fluid that will induce the chemical reaction that triggers hydrogen production in rocks. The main ingredient is water, and the team is testing "simple" materials for catalysts that will speed up the reaction and in turn increase the amount of hydrogen produced, says postdoc Yifan Gao.
"Some catalysts are very costly and hard to produce, requiring complex production or preparation," Gao says. "A catalyst that's inexpensive and abundant will allow us to enhance the production rate - that way, we produce it at an economically feasible rate, but also with an economically feasible yield."
The iron-rich rocks in which the chemical reaction happens can be found across the United States and the world. To optimize the reaction across a diversity of geological compositions and environments, Abate and Gao are developing what they call a high-throughput system, consisting of artificial intelligence software and robotics, to test different catalyst mixtures and simulate what would happen when applied to rocks from various regions, with different external conditions like temperature and pressure.
"And from that we measure how much hydrogen we are producing for each possible combination," Abate says. "Then the AI will learn from the experiments and suggest to us, 'Based on what I've learned and based on the literature, I suggest you test this composition of catalyst material for this rock.'"
The team is writing a paper on its project and aims to publish its findings in the coming months.
The next milestones for the project, after developing the catalyst recipe, is designing a reactor that will serve two purposes. First, fitted with technologies such as Raman spectroscopy, it will allow researchers to identify and optimize the chemical conditions that lead to improved rates and yield of hydrogen production. The lab-scale device will also inform the design of a real-world reactor that can accelerate hydrogen production in the field.
"That would be a plant-scale reactor that would be implanted into the subsurface," Abate says.
The cross-disciplinary project is also tapping the expertise of Yang Shao-Horn, of MIT's Department of Mechanical Engineering and DMSE, for computational analysis of the catalyst, and Esteban Gazel, a Cornell University scientist who will lend his expertise in geology and geochemistry. He'll focus on understanding the iron-rich ultramafic rock formations across the United States and the globe and how they react with water.
For Wicks at ARPA-E, the questions Abate and the other grant recipients are asking are just the first, critical steps in uncharted energy territory.
"If we can understand how to stimulate these rocks into generating hydrogen, safely getting it up, it really unleashes the potential energy source," he says. Then the emerging industry will look to oil and gas for the drilling, piping, and gas extraction know-how. "As I like to say, this is enabling technology that we hope to, in a very short term, enable us to say, 'Is there really something there?'"
