Technological developments across a range of established and experimental production methods could rapidly reduce the cost of green hydrogen to the point it is competitive with grey hydrogen, a panel of industry experts agreed yesterday at CeraWeek.

Despite electrolyser technology being established for decades, green hydrogen has been slow to take a significant share of the hydrogen market because costs have remained stubbornly high relative to supply sourced from natural gas.

Nel Hydrogen in January announced a target of $1.5/kg for green hydrogen by 2025, which would put it in a competitive position with grey hydrogen. There are “many things that come into play for that roadmap”, says Everett Anderson, vice president, advanced product development, Nel Hydrogen US.

“From just a capex perspective, we feel we can certainly drive costs down to well below 50¢/kg” Anderson, Nel Hydrogen

Anderson says the “price has come down significantly” already due to a range of factors including “new players into the market… [that have] broadened the supply chain, with established companies”.

There has also “certainly been innovation”, he says. “Design improvements have led to more efficient use of materials. There has been performance improvements with new materials that have increased the efficiency of electrolysers. And, in addition to that, there has been innovation on the manufacturing side… adding in automation, adding in continuous manufacturing processes, has driven down costs.”

The most important factor in achieving $1.5/kg is the continuing fall of renewable energy costs, which would reduce opex, while improvements to electrolysers are also reducing the capex component. “From just a capex perspective, we feel we can certainly drive costs down to well below 50¢/kg,” says Anderson.

Petronas plan

Malaysian NOC Petronas has created a strategy to make cost-competitive green hydrogen that is underpinned by a combination of technological improvements and falling renewable energy costs

 “Green hydrogen is something that requires a little bit of transformational technology, shifting just a little bit,” says Mahpuzah Abai, CEO of Petronas Technology Ventures.

“We are moving towards competitive green hydrogen production... This is very much aligned to the great potential of renewable energy in Malaysia, namely in solar and hydro.

“As we embark into our own hydrogen programme, we are developing an advanced electrolysis technology. It is now being demonstrated. The cost of hydrogen we are looking into is around $1-2/kg, definitely. We are looking into how best we can improve these technologies so that they become more efficient in producing hydrogen.”

"We are looking into how best we can improve these technologies so that they become more efficient in producing hydrogen" Abai, Petronas Technology Ventures

Nel is unusually a developer and marketer of both alkaline and proton exchange membrane (PEM) electrolysers, the two commercial low-temperature electrolysis technologies. “In general, it is too early to make a choice of one versus the other… in the energy transition both have unique characteristics that apply to to different market opportunities,” says Anderson.

Alkaline technology has been around for almost a century. “From a developer perspective, alkaline today is lower cost than PEM technology. It has a track record and has been demonstrated at scale. So, from a development risk perspective, if that is a driver for a particular project, it may be more interesting than the newer technology.”

Nel is continuing to invest in alkaline technology and Anderson says costs will further decrease as it builds scale. “We are building a gigafactory that will be online this year that will have five times the capacity of worldwide electrolyser production  in 2019. Things are changing very rapidly.”

On the PEM technology side, another cost-reducing dynamic is in play. “One of the advantages of the PEM technology is that it is very synergistic with the PEM fuel cell technology that is being used widely now in various mobility applications. You can leverage somewhat the developing supply chain on the fuel cell side with the PEM electrolysis side... the opportunity cost curve is steeper than for alkaline.”

Future technologies

Beyond the established low-temperature electrolyser technologies, there are technologies at the development stage involving high-temperature electrolysis—such as solid oxide electrolysis—that could make a big contribution to achieving net-zero on a 2050 timescale.

“The value proposition of high-temperature electrolysis systems is that electrical energy requirements are reduced in lieu of thermal energy input into the process,” says Dharik Mallapragada, research scientist, MIT Energy Initiative.

“If you think about applications, particularly in the context of hydrogen use for industry, you may have some synergies with certain high-temperature processing applications.”

Hydrogen has been suggested as a zero-carbon solution for hard-to-abate applications such as steelmaking that necessarily involve high temperatures, which could be fed back into the electrolysis process.

“High-temperature electrolysis systems are challenged today by reliability issues” including sealing systems at “those types of pressures and conditions”, he says. “But we are seeing development of materials.”

The other high-temperature technology that has received a lot of interest over the last year is methane pyrolysis, which produces hydrogen from natural gas without the byproduct of carbon dioxide that would otherwise need to be captured and stored.  

“You could think about it as basically decomposing methane at high temperatures to produce solid carbon instead of carbon dioxide, says Mallapragada. “This has some downsides, but potentially some upsides as well.”

“High-temperature electrolysis systems are challenged today by reliability issues” Mallapragada, MIT Energy Initiative

The downside is that you would produce less hydrogen from the same feed of methane, by volume. “The advantage is that you may be able to produce solid carbon, which might, if the structure and morphology of that solid carbon is optimised, have some significant structural properties that could make it valuable and hence reduce the cost of the hydrogen that you are producing.”

This technology is still at a fairly early stage. “But we are seeing a lot of venture and federal research dollars being directed towards its development,” he says.

Another key advantage is that natural gas could continue to be transported through the high-pressure pipeline system. Modular methane pyrolysis units could be installed at the head of the pipeline close to where the hydrogen is consumed, which means hydrogen could be delivered to the end user with lesser demands on infrastructure.

“The main challenge is around the solid-gas separation that is inherently involved in these types of systems,” he adds.

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Author: Alastair O’Dell<BR>Senior Editor