Scientists at Sandia National Laboratories are conducting research to determine whether depleted oil and natural gas reservoirs can be used for storing hydrogen, a carbon-free fuel. Hydrogen is a clean fuel that can be produced using renewable energy sources and has various applications, including electricity generation, powering heavy industry, and fueling vehicles with fuel-cell technology. Storing hydrogen is crucial for its long-term and seasonal use, especially when energy needs exceed the supply from renewable sources.
While hydrogen has a lower energy density compared to carbon-based fuels, making it challenging to store in large volumes on the surface, underground storage presents a promising solution. The research team at Sandia is investigating whether hydrogen stored in depleted oil and gas reservoirs will remain trapped in the rock or leak out. They conducted experiments and computer simulations to study the interaction of hydrogen with sandstone and shale, which form the body and seal around reservoirs.
The results showed that hydrogen does not stay inside sandstone after it is pumped out, but up to 10% of the adsorbed gas remains trapped in shale. Computer simulations confirmed these findings. Additionally, the team found that hydrogen does not preferentially enter the watery gaps between mineral layers of clay commonly found in shale, indicating minimal loss of hydrogen in clay.
The research also addressed the risk of contamination when hydrogen is injected into depleted natural gas reservoirs. It was found that residual natural gas can be released into the hydrogen, resulting in a small amount of carbon dioxide when the hydrogen is burned. Further studies are being conducted to understand the interaction between hydrogen and leftover oil in depleted oil reservoirs.
The findings from this research will inform large field-scale tests of underground hydrogen storage, with the goal of demonstrating the feasibility of using depleted oil and natural gas reservoirs for hydrogen storage. This research contributes to the development of widely distributed means of storing large quantities of hydrogen, which is essential for creating a hydrogen economy and decarbonizing the energy sector.
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