Far from being low-carbon, greenhouse gas emissions from the production of blue hydrogen are “quite high”, concludes a study by Robert W. Howarth and Mark Z. Jacobson, researchers at Cornell University and Stanford University, respectively, published 12 August in the scientific journal Energy, Science and Engineering.
While blue hydrogen is often presented as low-carbon because it is coupled with CO2 capture and storage (CCS) technologies, the two researchers examined the life-cycle greenhouse gas emissions of blue hydrogen, taking into account not only CO2 emissions but also unburned methane leakage.
Their conclusion: total CO2 equivalent emissions for blue hydrogen are only 9-12% lower than for grey hydrogen, i.e. hydrogen produced by steam reforming of methane in natural gas (without CCS technologies).
Although carbon dioxide emissions are lower for blue hydrogen, fugitive methane emissions are higher than for grey hydrogen because of the increased use of natural gas to power carbon capture, the two researchers explain.
Furthermore, they estimate that the greenhouse gas footprint of this type of hydrogen is over 20% higher than that of burning natural gas or coal for heating and some 60% higher than that of burning diesel for heating.
For them, the use of blue hydrogen to fight climate change seems “difficult to justify”. Especially since their results are based on the “optimistic and unproven” assumption that captured carbon dioxide can be stored indefinitely.
On the part of the European Commission, the development of “low carbon” hydrogen - defined in the ‘hydrogen strategy’ as hydrogen from fossil fuels with carbon capture and hydrogen produced by electricity, with significantly reduced life-cycle greenhouse gas emissions compared to current hydrogen production (see EUROPE 12523/1) - is seen as a necessary transitional step pending sufficient development of renewable hydrogen (produced by electrolysers powered by electricity from renewable energy sources).
See the study: https://bit.ly/3gWHSWj (Original version in French by Damien Genicot)