It is very challenging to know how much hydrogen (H2) is released from the value chain since insufficient and, when available, no standardized data can be found in the literature. However, it is essential to cover this knowledge gap to perform any credible and scientifically validated research regarding the H2 value chain impact on the climate change.

The literature is full of studies investigating and calculating the risk of H2 leakages in case of failures, accidents, and emergencies. But significant knowledge gaps exist about the amount of anthropogenic H2 (in the atmosphere) from the H2 value chain. The research community needs to address this by improving the capability to quantify small and large releases, delivering validated methodologies and techniques for measuring or calculating them. A universally accepted and open-access inventory is needed as soon as possible. Likewise, an open access and comprehensible tool that is easy to be used is also asked by the stakeholders to better quantify the leaks from the whole in H2 value chain while the momentum is fast gathering to upscale H2 energy applications.