ENERGY SECURITYSubterranean Storage of Hydrogen
Hydrogen is an important clean fuel: It can be made by splitting water using solar or wind power, it can be used to generate electricity and to power heavy industry, and it could be used to energize fuel-cell-based vehicles. Sandia scientists are using computer simulations and laboratory experiments to see if depleted oil and natural gas reservoirs can be used for storing this carbon-free fuel.
Imagine a vast volume of porous sandstone reservoir, once full of oil and natural gas, now full of a different, carbon-free fuel — hydrogen.
Sandia scientists are using computer simulations and laboratory experiments to see if depleted oil and natural gas reservoirs can be used for storing this carbon-free fuel. Hydrogen is an important clean fuel: It can be made by splitting water using solar or wind power, it can be used to generate electricity and to power heavy industry, and it could be used to energize fuel-cell-based vehicles. Additionally, hydrogen could be stored for months and used when energy needs outpace the supply delivered by renewable energy sources.
“Hydrogen would be good for seasonal and long-term storage,” said Sandia chemical engineer Tuan Ho, who is leading the research. “If you think of solar energy, in the summer you can produce a lot of electricity, but you don’t need a lot for heating. The excess can be turned into hydrogen and stored until winter.”
However, hydrogen contains much less “bang” in a set volume than carbon-based fuels such as natural gas or propane and is much more difficult to compress, Tuan said. This means storing huge amounts of hydrogen in metal tanks on the surface is just not feasible, he added.
Hydrogen can be stored underground in salt caverns, but salt deposits are not widespread across the U.S., said Don Conley, the manager for Sandia’s underground hydrogen storage work. Therefore, Tuan’s team is studying if hydrogen stored in depleted oil and gas reservoirs will get stuck in the rock, leak out or get contaminated.
Tuan’s team recently shared their findings in a paper published in the International Journal of Hydrogen Energy.
Leaky rocks or secure storage?
First, Tuan’s team studied if hydrogen would get stuck in the sandstone or shale that forms the body and seal around many oil and gas reservoirs, or if the gas would leak out. Sandstone is composed of sand-sized grains of minerals and rocks that have been compressed over eons; sandstone has a lot of gaps between particles and thus can store water in aquifers or form oil and gas reservoirs. Shale is mud compressed into rock and is made up of much smaller particles of clay-rich minerals. Thus, shale can form a seal around sandstone, trapping oil and natural gas.
