Skoltech researchers have found a way to produce hydrogen from natural gas with 45% efficiency right in the gas field by injecting steam and a catalyst into a well and adding oxygen to ignite the gas. Catalyst-assisted combustion produces a mixture of carbon monoxide and hydrogen, from which the latter can be easily extracted. This technology will help accelerate the transition from fossil fuels to clean hydrogen power. The study was published in Fuel.
I mean, all that methane coming out would probably be at least as bad, and the cavity had previously been filled with methane.
It’ll be a cavern deep under a lot of rock. If it can contain methane for zillions of years, I imagine that it can contain carbon dioxide.