Addressing hydrogen leakage will make green hydrogen an even better climate solution

2 February 2024
By Sam Bartlett

We all know that green hydrogen is vital to achieving net zero: we won’t be able to decarbonise key parts of our economy without it. This week we look at the importance of addressing hydrogen leakage in our own value chain to make the climate benefits even greater.

Hydrogen leakage and its climate impact is certainly an area that needs to be looked at more closely, and the updated Green Hydrogen Standard adopted at COP28 tackles the issue.

Hydrogen is not a greenhouse gas. However, it is a small, leak-prone molecule that can indirectly warm the climate through chemical reactions with greenhouse gases like methane, ozone, stratospheric water vapor and aerosols. In 2023, research led by Norway’s CICERO Centre for International Climate Research estimated the 100-year time-horizon Global Warming Potential (GWP100) of hydrogen emissions to be 12 times more than carbon dioxide emissions. Over 20 years it could be 37 times more. Welcoming the study, the Environmental Defense Fund noted that “these warming impacts are short-lived, both because hydrogen’s lifetime is short, and because its indirect effects through increasing GHG amounts only last a few decades.”    
The CICERO researchers’ conclusion is clear: “it will be important to keep hydrogen leakages at a minimum to accomplish the benefits of switching to a hydrogen economy”. In 2022, RMI concluded that Hydrogen Is Not a Significant Warming Risk, although this “depends on producing, storing, transporting, and consuming hydrogen in a way that minimizes emissions at each step. Every choice made in the hydrogen supply chain will be crucial in determining the ultimate emissions benefit achieved”.

The amount of hydrogen currently emitted from infrastructure is uncertain as emissions have not been consistently measured. Esquivel-Elizondo et al (2023) report that present and future value chain emission rate estimates vary widely (0.2% to 20%): “the largest ranges in estimated emissions rates are associated with liquefaction (0.15% to 10%), liquid hydrogen transporting and handling (2% to 20%), and liquid hydrogen refuelling (2% to 15%)”.

The impact of hydrogen emissions will be negligible in some cases, but potentially very significant where hydrogen emissions and leakage are not addressed.

Most hydrogen standards and certification schemes do not address this issue. The IPHE’s Methodology for Determining the Greenhouse Gas Emissions Associated with the Production of Hydrogen states: “The impacts of hydrogen as an indirect GHG have not been considered as part of this work given current focus on (direct) GHG emissions accounting” (page 57). It will be important to follow this issue as the ISO builds on its new methodology (based on IPHE’s) for assessing greenhouse gas emissions for hydrogen production and transport which is set to become a fully-fledged standard over the next year or so.
Hydrogen emissions are also not included in the EU’s methodology defining “renewable hydrogen” or in the United States’ GREET model which is used to determine the eligibility for large tax credits under the Inflation Reduction Act. The UK’s Low Carbon Hydrogen Standard is one of the only national standards to address the issue, including guidance on minimising fugitive hydrogen emissions.

GH2’s Green Hydrogen Standard was updated at COP28 in December 2023 to address this issue. GH2 accreditation and certification requires that the project operator:
(1) has evaluated the risks associated with hydrogen emissions associated with the project; (2) has developed a plan to minimize hydrogen emissions; and (3) has established a system to monitor and measure hydrogen emissions.

We believe this is a practical and proportionate first step. It establishes a clear expectation to address and mitigate these risks. A requirement to measure and reduce emissions is clearly not sufficient. A threshold is ultimately needed, aligned with net zero targets. GH2 has therefore committed to review accredited projects on an annual basis and to establish a maximum threshold for hydrogen leakage in accordance with emerging best practice.