Hydrogen strategies that promote blue as well as green varieties of the fuel carry significant risks and could lead to greater greenhouse gas emissions, according to new research from the Australian National University (ANU).

Many countries’ hydrogen strategies typically define ‘clean hydrogen’ as including both green and blue versions. While green hydrogen has no emissions, the emissions from blue hydrogen production can vary widely depending on carbon-capture rates and upstream fugitive methane emissions.

“At the moment, discussions about clean hydrogen lead to a lot of uncertainty about emissions intensity of what a future hydrogen industry would be,” says Thomas Longden, an energy economist at ANU.

“Our key concern is the misconception that blue hydrogen is classified as clean, and that is not necessarily the case.”

$22/t – Minimum CO₂ price needed to make blue hydrogen competitive with grey

Widely discussed research from Cornell and Stanford universities in August found that production of blue hydrogen may harm the climate more than burning fossil fuels. The research was disputed by the blue hydrogen industry.

The ANU research differs from the Cornell and Stanford’s in that it evaluates different national hydrogen strategies as well as the cost of carbon capture and storage (CCS) with low and high rates of emissions capture. The research also says a carbon price somewhere between $22-46/t CO₂ is needed to make blue hydrogen cost-competitive with grey.

Fugitive methane emissions   

The ANU researchers argue energy intensity calculations for blue hydrogen do not usually account for fugitive methane emissions, which escape when natural gas is extracted and processed. And fracked gas, which is becoming increasingly common, tends to produce more fugitive emissions than non-fracked gas, adds Longden.

The waste CO₂ from the production of blue hydrogen must be stored, and this is both expensive and comes with the possibility of leakage if the site is not well chosen, he adds. Longden argues that steam methane reforming with CCS—the most common way of producing blue hydrogen—actually uses more natural gas than the production of grey hydrogen.

Longden adds that, while CCS for hydrogen may be well understood, it has yet to be widely deployed. "Mature CCS technologies could avoid 50-90pc of emissions, but they are expensive, and become more expensive as the capture rate increases," he says. 

"CCS is an expensive option for emissions reduction, with most estimates for the cost of carbon-capture being above $59/t CO₂. These estimates increase to about $78/t CO₂ for high capture rates.”

Cost estimates also typically underestimate CO₂ transport and storage, and generally do not include monitoring and verification, he notes.

Strategic variations

National hydrogen strategies vary in how they treat climate emissions. Only Chile, France, Portugal, New Zealand and Spain prioritise green hydrogen alone, say the authors. The EU and Germany prioritise green hydrogen, with blue hydrogen discussed as a transitional or bridge measure.

Of the other countries that promote blue hydrogen, only Australia and Canada provide detail of expected carbon-capture rates for blue hydrogen to be considered ‘clean’. These rates are given as at or over 90pc and are therefore “highly optimistic”, according to the researchers.

“Discussions about clean hydrogen lead to a lot of uncertainty about emissions intensity” Longden, ANU

Additionally, potential large hydrogen importers such as Japan and South Korea have little or no incentive to buy green hydrogen rather than blue because any process emissions will be accounted for in the producer country, Longden notes.

Advocates of blue hydrogen argue that questions about the environmental credibility of blue hydrogen could be dealt with by clear and enforceable standards for all low-carbon forms of the fuel.

A ten-year tax credit for hydrogen production currently proceeding through the US legislative process has a sliding scale of compensation based on the emissions intensity of the hydrogen being produced.

Many in the US and elsewhere have argued that blue hydrogen is a necessary stepping stone to green as it is faster and cheaper to deploy and can help build out demand infrastructure ahead of a global transition from blue to green hydrogen after 2030.

---

Author: Ros Davidson