A new life-cycle analysis of potentially low-greenhouse-gas options for producing hydrogen in Europe finds that only hydrogen produced using renewable electricity can be effectively zero-emission, and that hydrogen pathways involving fossil fuels, even with carbon capture and storage, have greenhouse-gas (GHG) intensity high enough to make it unlikely they can contribute to meeting the European Union's climate targets. The study, from the International Council on Clean Transportation (ICCT), also found that waste-based biomethane production pathways generally have negative GHG intensity, but are subject to significant uncertainties.
source https://techxplore.com/news/2021-10-life-cycle-greenhouse-gas-emissions-biomethane.html
