@croselund @chrisnelder First of all, do take a few minutes of time and read the reviewer comments ("Interactive discussion") on the paper of the authors: https://acp.copernicus.org/articles/22/9349/2022/acp-22-9349-2022-discussion.html

The whole topic and the specific accounting is a bit disputed.

Where they are right: H2 leaking into the atmosphere will have some climate impact. It is best to prevent that.

@croselund @chrisnelder But there is a big difference between natural gas and H2 leaks: While NG is usually cheaply available and companies have not cared much about leakage (economic argument: If you get it basically for free, why spent money on detecting and fixing small leaks)? The IEA had a nice figure on abatement costs for CH4 leakages.

Abatement costs are estimated to be negative in some cases (sic!).

From here:
https://www.iea.org/reports/methane-tracker-2021/methane-abatement-and-regulation

@croselund @chrisnelder Coming back to H2: The economics are a bit different. A lot of investment and costs go into producing every single molecule of H2. It's much more precious than your average natural gas.
So there is an economic incentive to detect and reduce leakage.

In the paper by Ocko and Hamburg (2022) between 1-10% leakage of H2 is assumed. That. Is. A. Lot.

It also directly translates to H2 costs being 1-10% higher.

I doubt we'll see two digit leakage rates in the future.

@croselund @chrisnelder So my bottom line is:

* Improve monitoring and detection: Certainly
* More policy attention: Certainly (e.g. H2 emissions are not monitored like other Kyoto protocol gases)
* Stricter limits on H2 leakage: Yes

The more we electrify, push energy efficiency and reduce transport distance for H2, the less H2 leakage will become an issue.

Using derivatives of H2 instead of molecular H2 will also help.