IOGP comments to R. W. Howarth and M. Z. Jacobson (2021): How Green is Blue Hydrogen?

This document provides IOGP’s comments on Howarth and Jacobson’s publication (2021) 'How Green is Blue Hydrogen?'.


Robert W. Howarth and Mark Z. Jacobson (H&J) recently published a paper on the life-cycle GHG emissions for blue hydrogen, claiming that the GHG footprint of blue hydrogen is over 20% higher than burning natural gas for heat generation. Blue hydrogen is produced by the (steam) reforming of natural gas, while the associated CO2 emissions are captured and injected mostly back into reservoirs for safe underground storage. When used, blue hydrogen does not emit carbon. H&J analyse CO2 and methane emissions along the life-cycle of blue hydrogen from the production and transmission of natural gas to its use for hydrogen production in steam reforming processes, including the capture and storage of the CO2 emitted in that process.


H&J’s claim is the result of an aggregation of multiple extreme assumptions which create a misleading doubt about the important role blue hydrogen can have in cost-efficiently contributing to climate goals across the globe, including climate neutrality by 2050 in Europe:

  • Blue hydrogen can supply demand for hydrogen from hard-to-electrify segments of the industrial, transport and heating sectors
  • Blue hydrogen can support the timely development of the markets and infrastructure necessary to achieve the EU’s climate ambitions
  • Blue hydrogen is based on proven technologies which are available now at industrial scale and at significantly lower cost than green hydrogen, and for a long time with lower emissions than electrolysis-based hydrogen produced with average grid electricity

Key Comments

  • H&J assume unrealistically high methane leakage rates from the natural gas value chain
  • H&J use an extreme assumption regarding the Global Warming Potential (GWP) of methane over a 20-year horizon
  • H&J do not accurately reflect the current state or future technology advancements of carbon capture technologies
  • H&J do not recognise that both natural gas reforming and CO2 capture processes could rely on low-carbon energy
  • H&J does not consider that green hydrogen produced with grid-based electrolysis will for a significant amount of time generate higher emissions than blue hydrogen

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