Methane electrolysis for producing hydrogen

(Story reproduced with kind permission from Energy News)

Methane electrolysis may be a cost-effective method for New Zealand hydrogen production, Worley vice president for onshore upstream and midstream Peter Cox says.

The process uses up to five times less electricity than water electrolysis – splitting hydrogen from water molecules – which could have important benefits for lowering emissions from industrial gas users in the transition to a net-zero economy.

The process does not release CO2 and has a negative carbon intensity when biomethane is the base ingredient, Cox says. 

“You’re effectively taking carbon out of the atmosphere.”

Methane electrolysis splits hydrogen and solid carbon from the methane molecule – CH4. 

In addition to producing hydrogen, the carbon is released as solid-state carbon black rather than CO2. That means gas used in the process does not release greenhouse gas emissions, Cox says.

“Methane electrolysis combined with other existing technologies represents a credible opportunity for the gas industry to move towards net zero emissions across the whole value chain,” he says.

Methane is commonly used to produce hydrogen globally, through steam methane reforming. That technology reacts the methane with steam under pressure in the presence of a catalyst.

It produces hydrogen and carbon dioxide in a two-stage process. Cox says this is a mature technology, but it requires carbon capture and storage to reduce emissions and is “often technically challenging in some regions”. 

Also, not all carbon is captured and stored during that process.

He says that while there is a public perception that to decarbonise the economy the “hydrocarbons industry has to be completely turned off as soon as possible”, methane electrolysis means it is “plausible to move towards a zero-emissions gas industry going forward”.

“There’s actually many different pathways to achieve decarbonisation.”

The solid carbon produced can also be sold, improving the economics of the technology even further, Cox says.

Carbon black is a globally traded commodity used in tyres amongst other applications. Other applications are being developed including for use in cement, fertilisers, batteries, and building products.

He also sees potential for its use in green steel and lower carbon aluminium production.

Methane electrolysis – sometimes referred to as methane pyrolysis – is still a young technology and not widely understood.

Cox says industries tend to be conservative about adopting new technology and while there are a number of plants operating globally from different manufacturers, “they’re virtually all pilot plants”.

However, there is strong interest in Europe and the US where there are incentives to decarbonise gas usage.

Worley has been doing a lot of work on low-emission and ‘green’ hydrogen. But that is more expensive than current hydrogen produced globally.

“There’s that price gap we have been trying to address,” Cox says. “This is where methane electrolysis has got our attention.”

Worley New Zealand energy transition manager Nick Stonier says the technology could be beneficial for the transition here.

Using up to five-times less electricity than water electrolysis equates to reductions in investment requirements for transmission and distribution network upgrades to power it, Stonier says. 

"One of the main benefits of this pathway is that, from the gas side, a large part of the infrastructure required already exists, reducing the capital investment required.”