Underground Hydrogen Could Supply Power for 170 Millennia
Source： eepower
The demand for hydrogen is expected to increase sixfold over the next 25 years, rising from 90 million metric tons in 2022 to 540 million metric tons by 2050. Driving the surge is hydrogen’s role as a clean-burning fuel, making it a key solution for reducing carbon emissions from fuel sources. Unfortunately, producing hydrogen is not an inherently clean-burning process and currently contributes to about 2.4% of global carbon dioxide emissions, which limits its full potential as a solution for a net-zero emissions future.
Hydrogen can deliver large amounts of energy and is currently used in petroleum refining and fertilizer production, with its role rapidly expanding in the transportation and utility sectors. Developing completely fossil fuel-free methods of producing hydrogen is essential if it is to serve as a true replacement for fossil fuels.
Approaches using renewable energy sources like wind or solar are being explored, but these methods are not yet commercially viable. Meanwhile, a research team from the University of Oxford, Durham University, and the University of Toronto is promising a temporary solution in the utilization of natural hydrogen. They have found enough underground hydrogen stores to meet the world’s energy needs for the next 170,000 years.
Carbon-Free Fuel, Carbon-Full Production
Hydrogen is a clean-burning fuel that only produces water, making it an attractive option for replacing natural gas, which produces both water and carbon dioxide when burned. Several methods are currently used to produce hydrogen: thermal processes involving steam reforming of natural gas which emits carbon dioxide (grey hydrogen), extraction from natural gas but the carbon dioxide is captured and either stored or repurposed (blue hydrogen), and using renewable energy to power an electrolysis reaction of water with no carbon emissions produced (green hydrogen), among other less common methods.
Despite green hydrogen’s availability, the cost is at least twice as expensive as producing grey and blue hydrogen. While green hydrogen’s production costs are expected to decrease due to increases in volume output and technology efficiency, a more scalable solution is necessary to support industry decarbonization efforts.
Here is where natural hydrogen comes in.
Natural Hydrogen
Hydrogen is the most abundant chemical element on Earth, present in almost all living things, but is rarely found in its gaseous state. According to the England-based research team, naturally occurring hydrogen is generated in the Earth’s crust through chemical and radioactive processes. Enough natural hydrogen has accumulated over the last billion years to potentially meet the equivalent of 170,000 years’ of current global oil consumption.
Expectations that accumulations of natural hydrogen could be widespread were sparked following reports of high-purity (over 97 percent) hydrogen found in the Bourakebougou gas fields in Mali in 2018. However, a lack of consistent sampling and measurement makes it difficult to fully understand how much hydrogen exists and where it is located.
The global distribution of hydrogen-potential terranes. Black circles indicate an example of each terrane type with known notable hydrogen accumulations. Image used courtesy of Ballentine et al.
Extracting natural hydrogen stores is expected to have a low carbon footprint. While the exact cost will depend on factors like gas purity, flow rates, and the gas field sizes, viable natural hydrogen reserves could provide a low-carbon, commercially competitive hydrogen source to support the global energy transition.
However, natural hydrogen is not a renewable resource, as its regeneration occurs over tens to hundreds of years. It is intended to help bridge the supply gap while green hydrogen remains too expensive, rather than serve as a long-term solution.
Exploration Recipe to Locate Hydrogen Stores
Hydrogen accumulates across the Earth’s crust in a range of tectono-stratigraphic settings, but finding these accumulations depends on using the right ingredients, measurements, timing, and temperature. Otherwise, the result will fall short. The research team is devising an “exploration recipe” that can be used to locate natural hydrogen stores.
With the right “recipe,” the team hopes to develop a repeatable process, with the potential to reliably identify hydrogen stores that are economically viable to extract.
The team believes that through this process, finding large sources of hydrogen is possible, but high concentrations like the one found in Mali are likely to be rare.
The Future of Hydrogen
Ultimately, discovering a cost-effective and scalable way to produce hydrogen is essential for it to play a major role in the global energy transition. If natural hydrogen can be extracted at scale, it could serve as a valuable interim solution while green hydrogen becomes more affordable.
Hydrogen has potential uses across a wide range of industries, including steel production, transportation, aviation, and power generation, but the challenges of high production costs, infrastructure, and related carbon emissions still need to be addressed in order to truly have an impact.