Blue hydrogen could produce more emissions than burning natural gas, academic study finds

Scientists are warning that 'blue' hydrogen, which is produced by splitting natural gas and capturing process emissions, could generate 20% more emissions over its life-cycle than burning the natural gas in the first instance.

Pictured: One of Shell's hydrogen production facilities. Image: Shell

Pictured: One of Shell's hydrogen production facilities. Image: Shell

The figure is a headline conclusion of a new study published in the journal Energy Science & Engineering today (12 August) by a team of researchers at Cornell University, New York, and Stanford University, California.

While proponents of blue hydrogen often claim that more than 90% of the emissions resulting from the production process can be addressed using onsite carbon capture and storage (CCS) or carbon capture and utilisation (CCU) arrays, the study states that the capture rate varies from 15% to 90% for facilities currently in commercial operation. The scientists use a base rate in which 85% of emissions are captured.

Moreover, these capture rates are only associated with the carbon dioxide released by the steam methane reforming (SMR) part of the process – the process of heating the methane component of natural gas with steam to produce a mix of carbon monoxide and hydrogen. Methane released in the extraction of natural gas will remain.

“Several non-peer-reviewed reports suggest that it may be possible to reduce carbon dioxide emissions for blue hydrogen by 56% (when only the SMR process is treated) to 90% (when exhaust flue gases are also treated) relative to grey hydrogen,” the report states. “However, no data have been presented to support these estimates, and they apparently do not include emissions associated with the energy needed to drive carbon capture. Our results using a full life-cycle assessment show [these] assumptions are too optimistic.”

The study also points to the ways in which using blue hydrogen is inefficient; it takes many tonnes of natural gas to produce a single tonne of blue hydrogen.  

The co-author of the study, Cornell University’s professor of ecology and environmental biology Robert Howarth, said: "Politicians around the world, from the UK and Canada to Australia and Japan, are placing expensive bets on blue hydrogen as a leading solution in the energy transition.

"Our research is the first in a peer-reviewed journal to lay out the significant life-cycle emissions intensity of blue hydrogen. This is a warning signal to governments that the only 'clean' hydrogen they should invest public funds in is truly net-zero, green hydrogen made from wind and solar energy."

On the UK policy piece, the Ten-Point Plan committed £500m of Government funding to hydrogen generation, in the hopes of the nation hosting 5GW of “low-carbon” generation capacity by 2030.

The term “low-carbon” is used as an umbrella for both blue and green hydrogen production, the latter of which involves splitting water using electrolysers powered with 100% renewable energy. Ministers have stated that the Government is taking a “dual-track” approach but, by some calculations, 75% of the low-carbon hydrogen funding it has provided to date has gone to the blue hydrogen sector.

Responding to the new study, the University of Cambridge’s professor of mechanical engineering David Cebon said: “This landmark paper sheds light on the key unknown in the UK’s hydrogen debate: the greenhouse gas footprint of blue hydrogen. The calculation method is rigorous, the assumptions are all solid and the results are stark.

“Blue hydrogen cannot be considered ‘low-carbon’ or a ‘clean’ solution.”

The publication of the study comes as the Department for Business, Energy and Industrial Strategy (BEIS) is planning to publish the Hydrogen Strategy, which should add longer-term clarity to the Ten-Point Plan funding commitment. The Strategy had been due ahead of the start of Parliament’s summer recess on 22 July.

Several large businesses are betting on the UK Government continuing to support blue hydrogen. BP recently named a string of corporate buyers for its proposed blue hydrogen production facility in Teesside, for example, while Equinor has outlined plans to develop 1.8GW of blue and green hydrogen production capacity in the UK by 2030.

International relations

In related news, researchers at the University of Sussex have this week published a paper outlining how nations that currently have “significant geopolitical influence”, such as Saudi Arabia and Russia, will likely strive to maintain their positions as the world transitions away from grey hydrogen (purely fossil-fuel derived with no CCS or CCU).

The authors of the study, published in the journal Energy Research & Social Science, predict a struggle in the coming years between countries strongly oriented toward green hydrogen adoption, such as EU member states, and those hoping to benefit from export of blue hydrogen.

Co-author Morgan D Bazilian said: “In the shift away from fossil fuels to a low-carbon economy, the focus of geopolitical issues will likely change from a primacy of where these energy sources are found, to where the technology development centres and sources of critical materials are located.”

The study is entitled: ‘Industrial Decarbonisation via Hydrogen: A Critical and Systematic Review of Developments, Socio-technical Systems and Policy Options’.

Sarah George



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