It's been touted as a climate-friendly future alternative to fossil fuels - and now Kiwi scientists think they have a way to make so-called "green" hydrogen a viable reality.
A major new study, backed with an $8.4m grant from the Ministry of Business, Innovation and Employment, comes amid a major push by the Government to make green hydrogen a centrepiece of New Zealand's "just transition" away from oil and gas.
Currently, 95 per cent of hydrogen produced globally is "brown hydrogen" - or that produced from coal and natural gas - and was a driver of carbon dioxide emissions.
Green hydrogen, produced by splitting water into hydrogen and oxygen using electrolysis from renewable energy sources, has the benefit of being carbon neutral, yet remains expensive to make.
The project's leader, Dr John Kennedy of GNS Science, and his colleagues nonetheless see it playing a crucial role in New Zealand's low-carbon future.
They see the answer to making affordable, readily-viable green hydrogen in a system of water electrolysis called polymer exchange membrane, or PEM.
In contrast to the more commonly used alkaline electrolyser, PEM is better suited to working with the intermittent nature of renewable energy sources like wind and solar that could provide electricity for hydrogen production.
Just as importantly, it's readily adaptable to large-scale hydrogen production.
"However, PEM systems rely on catalysts based on noble metals that are rare, expensive and suffer from inefficiencies," Kennedy said.
"This drives up the cost of green hydrogen relative to fossil fuels."
Working with scientists across Canterbury, Auckland and Otago universities, along with other experts in Singapore, Germany, Australia and the US, Kennedy's team aims to overcome this barrier with new, high-performing materials.
"This entails working at the molecular level to design surfaces with specific properties that make them highly efficient as catalysts," he said.
"The research tackles challenges that are presently a barrier for large-scale hydrogen production. This includes fundamental physics, catalyst chemistry, and the design of electrocatalytic devices."
The project, running over five years, will also investigate what factors might drive public buy-in to green hydrogen, along with what economic benefits could be reaped from producing and exporting it here.
Some of the obvious applications for New Zealand were using it as an energy storage medium for dry hydro years, a fuel for heavy transport, and replacing fossil fuels for heating and industrial uses.
"It is also a potential export commodity, possibly in a transportable form such as ammonia."
New Zealand currently imported about 60 per cent of its energy in the form of oil and coal, and green hydrogen had the potential to make the country more self-sufficient in energy, he said.
"Hydrogen can replace fossil fuels for stationary power and transport industries that contribute 40 per cent of New Zealand's greenhouse gas emissions.
"This project has a goal of helping New Zealand meet its net carbon zero target by 2050."
The horizon-scanning H2 Taranaki Roadmap, produced by local agencies and formally launched last year by Prime Minister Jacinda Ardern, has already forecast that hydrogen will be increasingly produced using electricity to split water, with the only emission being oxygen.
The report found hydrogen could be utilised as a fuel, particularly for heavy vehicles, as a feedstock for products such as urea or methanol, or to store electrical energy for long periods of time from weeks to years.
A new network could include storage of hydrogen or synthetic natural gas in depleted gas fields, it said, and electricity generation using green hydrogen in Taranaki's gas-fired peaker plants.
But the oil and gas industry has questioned how much it would cost to produce, given the "enormous" amounts of electricity required.