The proton.energy website is very optimistic, maybe a bit too much. I see a number of (potential) problems:
- The technology uses "hydrocarbon reservoirs" which is a different word for existing oil and gas fields, so that makes the resulting fuel non-renewable.
- The exact process is not clear to me, but the paper they link to talks about water being injected and that may not be readily available in some situations (e.g. middle east deserts). On the other hand this page doesn't say anything about water, so perhaps they are using a different process?
- It's not clear to me how they are preventing other gases to escape when they pump up the hydrogen. Current oil extraction also involves capturing or flaring natural gas, which contributes to rising CO2 levels
- Hydrogen can be transported in current gas pipelines as the website claims, but some minor modifications are needed and the "without hardware changes" claimed by the website does not seem entirely incorrect1
This is not to say that (some of) these problems cannot be solved, but at the moment I'm still a bit skeptical. I don't think it will be as easy as the website suggests and I do wonder how close to carbon-neutral the resulting fuel will be.
1) Hydrogen makes metal brittle and despite all the reports that say current gas pipelines can be used with only small modifications, so far I haven't seen a good solution for this. Then again, this is outside of my knowledge area so perhaps there is a good solution.