Tech Insights

The Future of Hydrogen Could Be Found Underground

December 13, 2023 by Kevin Clemens

Deep below the Earth’s surface may lie vast amounts of naturally occurring hydrogen that could fuel power plants of the future. Harvesting this “white hydrogen” could mitigate some problems in current hydrogen production.

Many people view hydrogen as a viable replacement for fossil fuels. It can be pumped into a vehicle or used in a power plant to generate energy without producing carbon dioxide and other pollutants. In June 2023, the U.S. Department of Energy published a strategic framework for exploring opportunities for hydrogen to become a critical part of energy, transportation, and industry.

 

Forsterite, an iron-rich olivine mineral, interacts with underground groundwater to produce naturally occurring hydrogen.

Forsterite, an iron-rich olivine mineral, interacts with underground groundwater to produce naturally occurring hydrogen. Image used courtesy of Smithsonian National Museum of Natural History 

 

However, most current methods of producing hydrogen still involve using fossil fuels or result in carbon emissions. In the search for a better source of hydrogen, producers are now looking within the earth for a naturally occurring source of hydrogen called white hydrogen.

 

Making Hydrogen: Gray, Blue, and Green

The most common way hydrogen is produced is by using steam to separate it from carbon atoms in natural gas or through coal gasification—the method by which more than 90 percent of commercially available hydrogen is produced. This is called gray hydrogen, which releases vast quantities of carbon dioxide into the atmosphere. 

Theoretically, it is possible to capture carbon dioxide formed during hydrogen production from steam reforming and store it underground. This is called blue hydrogen. Oil companies are pushing this process to continue using fossil fuels in transportation even after refined petroleum products like gasoline and diesel fuel reach their endpoint. 

 

Types of hydrogen.

Types of hydrogen. Image used courtesy of the University of Calgary

 

The cleanest way to produce hydrogen is to use excess renewable energy from wind or solar. The process, called electrolysis, takes water and splits hydrogen from oxygen to create green hydrogen. The process, which does not produce greenhouse gas emissions, is pointed at by enthusiasts as the way forward, even if only a small percentage of hydrogen is currently made this way. 

 

Finding White Hydrogen

There is another way to obtain hydrogen gas. In the 1970s, oceanographic researchers discovered natural hydrogen gas seeping out near hydrothermal vents in mid-oceanic ridges. Oil drillers have been known to hit occasional pockets of natural hydrogen gas when searching for oil or natural gas, but they were thought of as a nuisance more than a source of hydrogen. In any case, the oil companies produced hydrogen by steam reformation

Recently, subterranean natural hydrogen has been getting much more attention. The U.S. Geological Survey (USGS) recently published information about the existence of natural hydrogen. It turns out that such hydrogen, now called white hydrogen, has been detected in parts of the United States, Australia, Africa, Russia, France, and other places in Europe. 

 

White hydrogen forms underground.

White hydrogen forms underground. Image used courtesy of USGS

 

Within the Earth’s crust, hot water occasionally interacts with iron-rich minerals like olivine. The oxygen in the water bonds to the iron, releasing the hydrogen that escapes to the surrounding rocks. Often, this hydrogen travels upward toward the surface and encounters microbes that feed upon it and produce methane (natural gas) as a byproduct. For this reason, it is unusual to find naturally occurring hydrogen in areas where natural gas is found. 

Some hydrogen formed is trapped where the rocks above form a seal to hold it in place. Over time, large amounts of the gas can accumulate and can be accessed by more or less the same drilling technology used to produce oil and natural gas. 

 

U.S. Sources of White Hydrogen

In the U.S., geologists have determined that two primary regions favor white hydrogen generation. Deep below the Atlantic Ocean are bands of iron that were deposited as the Atlantic basin formed. Surveys have confirmed that these iron deposits have interacted with water deep under the ocean floor to produce hydrogen, which, over time, has migrated along sedimentary layers toward the U.S. shoreline. It is predicted that accumulations of natural hydrogen will be found in pockets along the East Coast of the U.S. 

The central area of the U.S. is also of interest to geologists. The Midcontinental Rift formed about 1.1 billion years ago and ranges from Lake Superior to Iowa. The rift brought large amounts of iron-rich minerals toward the Earth’s surface, and those minerals interact with groundwater to create white hydrogen. A Colorado company called Koloma is searching for such hydrogen deposits in the U.S. Midwest. 

 

Midcontinent rift.

Midcontinent rift. Image used courtesy of USGS

 

Some geologists have suggested looking for places where hydrogen has accumulated might not be necessary. By injecting water into iron-rich rocks deep below the surface, it could generate hydrogen and pipe it back to the surface. The technology is similar to what is currently used to enhance geothermal energy production. 

 

Uses for White Hydrogen Production

Hydrogen gas can produce energy in several ways. In transportation, it can be used directly in an internal combustion engine to replace gasoline, but this does result in emissions of some pollutants like nitrides of oxygen that can create unhealthy smog. It’s also possible to combine hydrogen with oxygen in a fuel cell to produce water vapor and electricity that can be used to power an electric vehicle. Transportation applications require an effective way to store hydrogen onboard and a hydrogen distribution infrastructure for vehicles to refuel. 

A more feasible use for white hydrogen is to burn it in a base-load thermal power plant instead of natural gas. Such plants could be collocated above the subterranean hydrogen resource and provide nearly zero-emission electricity to the power grid. In the U.S., the location of potential hydrogen accumulations near East Coast population centers and in the industrial Midwest makes such plans attractive. 

Whether white hydrogen will reach its potential will largely depend on cost. At present, green hydrogen costs about $5 per kilogram to produce. This is more than twice the cost of gray hydrogen. Worldwide, governments are spending billions of dollars to try to bring down the cost of blue and green hydrogen and to create a viable hydrogen infrastructure. The U.S. Department of Energy (DOE) set a goal to bring hydrogen costs below $1 per kilogram by 2030, yet no money is currently being allocated to white hydrogen.  The hope is that by 2027 or 2028, the extent of naturally occurring hydrogen reserves will be better defined and that the feasibility of white hydrogen as a zero-emission energy source will become clearer.