(Re)Defining Clean Hydrogen: From Colors to Emissions

In the last few years, hydrogen has been elevated to a new position as the key player in the decarbonization efforts in line with the commitments to reduce emissions of greenhouse gases (GHGs), achieve carbon-neutrality by 2050, and reach the Paris Agreement targets to limit global warming to 1.5 degrees C, compared to pre-industrial levels.(1-4) The potential of hydrogen in the transition to clean energy was discussed in detail in the Winter 2021 issue of Interface, which was entirely dedicated to the multisectoral use of hydrogen produced from diverse pathways in a wide range of key sectors. I contributed to that issue with a Chalkboard article, Colors of Hydrogen, that discussed the status of the current and emerging hydrogen production pathways (Fig. 1) by presenting an updated view of the hydrogen colors paradigm based on a survey of many hydrogen reports and roadmaps.(5) Most reports have since then continued to highlight, with growing emphasis, the pivotal role of hydrogen in helping the world achieve carbon neutrality and transform the clean energy sector,(2-4,6-15) including the recently announced Clean Hydrogen Production Standard by the US Department of Energy and Global Hydrogen Review by the International Energy Agency (IEA).(4)

Automated summary

In recent years, hydrogen has gained importance as a key player in decarbonization efforts. It has significant potential in the transition to clean energy and various sectors, and numerous reports highlight its pivotal role in achieving carbon neutrality and transforming the clean energy sector.