April 11, 2024 [Interesting Engineering]- Researchers at Sandia National Laboratories are exploring a novel solution for storing hydrogen, a clean-burning fuel with the potential to revolutionize the energy sector. Their sights are set on a familiar target: depleted oil and natural gas reservoirs.
Hydrogen: A clean energy champion with storage challenges
Hydrogen offers a compelling proposition. It can be generated from renewable sources like solar and wind power through electrolysis, splitting water molecules into hydrogen and oxygen. This clean fuel can then be used to generate electricity, power heavy industries, and fuel vehicles equipped with hydrogen fuel cells – all without releasing harmful greenhouse gasses during operation.
One significant hurdle, however, lies in storing hydrogen. Due to its low energy density by volume compared to traditional fuels, storing large quantities of hydrogen in surface tanks proves impractical.
Subterranean solutions: Exploring depleted reservoirs
Sandia’s research team, led by chemical engineer Tuan Ho, is investigating the feasibility of utilizing depleted oil and gas reservoirs for hydrogen storage. These underground formations boast several advantages. They possess the necessary capacity to hold vast amounts of hydrogen, and the surrounding rock often acts as a natural seal, preventing leakage.
However, questions remain about hydrogen’s behavior within these reservoirs. Will it become trapped within the rock formations, leak out, or become contaminated by residual oil or gas?
Delving into the rock: Hydrogen’s interaction with sandstone and shale
Ho’s team conducted a two-pronged approach, utilizing both experiments and computer simulations, to understand how hydrogen interacts with the rock formations present in these depleted reservoirs. Sandstone, a common rock type, is composed of sand-sized mineral grains with ample space for fluids. Shale, on the other hand, is formed from compressed mud and features much smaller clay particles, making it denser and less permeable.
The research revealed that while hydrogen doesn’t stay put within sandstone after extraction, a promising finding emerged with shale. Up to 10% of the injected hydrogen became adsorbed within the shale sample, indicating its potential for storage.
Further simulations by Ho focused on a specific type of clay prevalent in shale surrounding oil and gas reservoirs – montmorillonite. The simulations suggested minimal hydrogen absorption or migration within the water-filled gaps between the clay layers. This translates to minimal hydrogen loss due to interactions with the clay, a positive indicator for underground storage.
Additional experiments are underway at collaborating institutions to validate these simulation results.
Potential contamination: Residual gas and leftover oil
While the initial findings regarding hydrogen interaction with rock formations are encouraging, another concern arises from contamination. Experiments and simulations conducted by Ho’s team suggest that residual natural gas in depleted reservoirs can be released into the injected hydrogen. This means the extracted hydrogen might contain trace amounts of natural gas, releasing small quantities of carbon dioxide when burned.
Ho’s team is currently delving deeper into this issue, investigating the potential contamination of hydrogen by leftover oil in depleted oil reservoirs using a combination of experiments and simulations.
Field tests and long-term considerations
The findings from this research will play a crucial role in guiding large-scale field tests planned by the Department of Energy’s Subsurface Hydrogen Assessment, Storage, and Technology Acceleration (SHASTA) project. These tests aim to demonstrate the viability of depleted oil and gas reservoirs for hydrogen storage.
Further research is necessary to understand how other factors like microorganisms and chemicals in depleted petroleum reservoirs might interact with stored hydrogen.
“If we want to create a hydrogen economy, we really need widely distributed means of storing large quantities of hydrogen,” says Don Conley, manager for Sandia’s portion of the SHASTA project. “Storage in salt caverns is excellent where it exists, but it can’t be the sole option. Depleted oil and gas reservoirs and aquifers offer a more geologically widespread solution for storing large volumes of hydrogen. This research is all part of the effort to decarbonize the energy sector,” he concludes.
Free Trial: Access 13,300 Tank Terminal and Production Facilities
13,300 tank storage and production facilities as per the date of this article. Click on the button and register to get instant access to actionable tank storage industry data
