Green hydrogen does not offer economically viable and scalable solutions to meet greenhouse gas (GHG) reduction goals for the buildings sector and has limited potential for the power sector, according to a new US study.

The US Infrastructure Investment and Jobs Act last year allocated $8bn to support regional hydrogen demonstration hubs, including at least two to explore the fuel’s use for heating and power generation.

But the idea that natural gas infrastructure can be repurposed to carry hydrogen is a false premise, with heating better suited to electrification, according to the peer-reviewed study by energy thinktank Energy Innovation, titled Assessing the Viability of Hydrogen Proposals.

“The existing body of research suggests blending hydrogen with natural gas for use in buildings or for power generation is highly inefficient and does little to reduce GHG emissions,” says the report. “Instead, it might thwart more viable decarbonisation pathways while increasing consumer costs, exacerbating air pollution, and imposing safety risks.”

The study argues green hydrogen would be better used for applications that have no alternative decarbonisation pathways—such as heavy industry.

Pilots underway

Since 2020, utilities have proposed at least 26 hydrogen pilot projects across more than 12 US states. Many of these proposals involve blending blue or green hydrogen with natural gas to reduce the carbon intensity of the fuel for use in buildings and power generation.

But blending at 20pc—the highest level possible without infrastructure modifications—offers only limited emissions reductions, according to the paper.

“Energy-efficient electric equipment and appliances hold an insurmountable advantage over their hydrogen counterparts” Energy Innovation

“Because hydrogen molecules produce less energy than methane when burned, a 20pc hydrogen blend would provide only 6-7pc of the mixture’s energy content,” it says.

To achieve greater emissions reductions than this, utilities will need to invest more in infrastructure to accommodate hydrogen blends above 20pc. Some utilities are keen for regulators to approve this because it would mean they could upgrade pipeline infrastructure using public grants.

Household appliances would also need to be upgraded, but these appliances are far better suited to electrification, according to the study.

“When comparing green hydrogen for use as a heating source versus direct electrification, energy-efficient electric equipment and appliances hold an insurmountable advantage over their hydrogen counterparts,” it says.

Electric heat pumps are 2-4 times more energy-efficient than natural gas-burning furnaces, while induction stoves outperform gas stoves by a factor of about three to one.

And due to the greater efficiency of electric appliances, a building decarbonisation pathway heavily dependent on the use of green hydrogen would require the buildout of substantially more renewable generation capacity relative to that required for electrification.

Furthermore, green hydrogen prices would have to fall to $0.50/kg not to add to consumer heating bills—even at a 20pc blend. This is half of the Biden administration’s target of $1/kg by 2030 for green hydrogen production.

“Hydrogen blending investments risk wasting time and ratepayer money en route to achieving minimal GHG emission reductions, only to face daunting financial and logistical roadblocks to achieving higher blends or a 100pc green hydrogen fuel network,” the study says.

Blending in gas turbines

Several US utilities are also proposing new investments in natural gas-fired power generators. But hydrogen achieves relatively low CO₂ emission reductions at lower blends in gas turbines while significantly increasing NOx emissions, driving up local air pollution levels, the study finds.

26 – Hydrogen projects proposed by US utilities

Hydrogen’s higher flame temperature means a 50/50 blend with natural gas would result in 35pc higher NOx emissions relative to burning 100pc natural gas. As a result, future regulations may require project owners install larger or more efficient NOx controls.

“Building new natural gas power plants based on the premise of utilities eventually transitioning them to burn 100pc green hydrogen may risk these assets being stranded, with such costs flowing to ratepayers or harming utilities’ financial position,” the report concludes.

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Author: Tom Young