Nova Scotia researchers helping to fill in pieces of green-hydrogen puzzle

In a laboratory tucked away on the fourth floor of the chemistry building at Dalhousie University, associate professor Mita Dasog points to an illuminated tube containing a brown liquid, which researchers hope will help shift society off fossil fuels.

The tube represents one part of the lab's work on producing green hydrogen through artificial photosynthesis.

 "We're essentially trying to mimic what plants do," Dasog says. 

It's part of a range of research the lab is undertaking that also includes investigating ways to bring costs down, as well as working with "alternative technologies." 

Both the provincial and federal governments have set ambitious targets for green hydrogen production. The federal government plans to start shipments of green hydrogen to Germany by 2025. Nova Scotia aims to begin granting leases in 2030 for offshore wind that would support green hydrogen production. 

But even as interest in green hydrogen grows, advocates and researchers say there are still barriers to overcome before the promise of supporting the energy transition can be fulfilled.

The cost problem

Nearly all of the hydrogen currently produced in Canada comes from fossil fuels — so-called "grey" and "black" hydrogen — which contributes to greenhouse gas emissions. 

But it can also be made from water, using electricity to split the molecules into hydrogen and oxygen through a process called electrolysis. When that electricity comes from renewable sources, the result is known as green hydrogen. 

But producing it is expensive, Dasog says. The cost is roughly three times as much as grey hydrogen, in part because precious and rare metals like platinum and iridium are used in electrolysis. So Dasog's lab is investigating materials that have the same properties but are more abundant, which would bring down the cost. 

After screening "hundreds and hundreds of materials," Dasog says, they've found a less expensive alternative that works as well as platinum. 

But the lab's work focusing on artificial photosynthesis could reduce costs in another way – by removing the need for electricity altogether.

This approach uses what's called a photocatalyst. In Dasog's lab, they're using materials made of silicon that are thinner than a billionth of a metre across and absorb sunlight the way plants' leaves do. These tiny photocatalysts can be suspended in water, or painted or printed on a surface, and react with the surrounding liquid.

"We can directly use the sunlight just like plants do to split water to make that hydrogen," she says. "So we remove the capital costs associated with electricity generation."

Sarrah Putwa is a graduate student in Dasog's lab who is working on improving the longevity of the nanoparticles, which would make the technology more versatile. 

"We could have water running over a bed of these photocatalysts, and there would be hydrogen being produced," she says. 

Putwa is from Tanzania, an East African country highly vulnerable to the effects of climate change, and says she's motivated by the technology's potential. 

"Working on a project that allows for the production in a sustainable fashion, I get that it won't solve the energy crisis, but it definitely plays an important role in alleviating it."

While a similar approach has been used in a pilot project in Japan, artificial photosynthesis doesn't exist yet at the commercial level. Part of the problem, Dasog says, is that there has been a lack of investment in the field, a challenge that was also identified in the federal government's hydrogen strategy. 

"Now there's a sudden interest and people want these mature technologies that unfortunately don't exist," she says, "they have not been able to go from lab to market because we haven't had the funding mechanisms to do so."

Renewables 'should be a priority'

Some advocates say the federal and provincial focus on developing green hydrogen for export also ignores another part of the energy transition: the use of renewables to power the grid directly.

Brenna Walsh, energy co-ordinator with the Halifax-based Ecology Action Centre, says green hydrogen could help address the intermittency of renewables. For example, by using wind power to generate hydrogen when excess power is being produced, that energy could be stored for when the wind isn't blowing.

But producing green hydrogen is a less efficient use of renewable energy than simply directing that energy to the grid, Walsh says.  

"We currently have a grid that's 50 per cent [fuelled by] coal. And so if we can have this renewable that directly displaces fossil fuels, that is something that should be prioritized," she says. 

"Focusing on kind of the incumbent renewables — wind and solar — and how we can move those onto the grid in ways that are effective, should be, I would think, a higher focus."

Nonetheless, Walsh says there is still a long-term role for hydrogen in hard-to-decarbonize sectors, such as fertilizers, aviation, marine transportation and long-distance trucking. 

Storage, transportation challenges

Some of the research underway in Dasog's lab could be applied in those contexts. One example is a project to make hydrogen from a powder that has received funding from Innovacorp to build up to commercial scale. 

This could make hydrogen easier to transport and store. 

Because hydrogen is a gas, it occupies a large volume. Export projects have been proposed in Nova Scotia to convert it to ammonia or to compress it, but both of those processes require energy.

Companies have also taken out licenses to explore using Nova Scotia's salt caverns for storage, and the province recently amended the Underground Hydrocarbons Storage Act to include hydrogen.

The research at Dasog's lab offers a different kind of storage solution — using powdered silicon to generate hydrogen through a chemical reaction as needed.

"This is hydrogen, but in a different form," says Sarah Martell, a PhD student in the Dasog lab who is researching on-demand hydrogen. "It's easier to carry around a jar of this brown powder compared to lugging around a gas tank, for example. So paired with a portable fuel cell, you could get electricity whenever you need it."

Martell says they've tested the process to show that it works as well with water from the Halifax harbour as with tap water. 

The silicon itself could be made from a variety of sources — such as sand, recycled packaging or grain husks — which would allow it to be adjusted to the local context. 

"We don't want any region to have monopoly over this material," says Dasog.

It could be used to power lightweight vehicles, as a power source in remote areas, or in emergency situations. 

With this and other ways of producing green hydrogen, Dasog says it's important to remember it's not only a fuel, but a way to help other sectors decarbonize.

"It's going to have an impact on many different sectors, and I think it's important to highlight that, because the scope is quite broad and the opportunities are quite broad." 

And while green hydrogen alone won't solve the energy crisis, Dasog says, the innovations her lab is working on could be part of the puzzle. 

"We really need multiple solutions."