'Hydrogen plays an exciting role in decarbonisation'

Recent years have witnessed a heightened interest in harnessing hydrogen's potential as a clean-energy source, largely driven by energy price dynamics. However, Dr Nigel P. Brandon's interest in hydrogen and fuel cell research predates this by over 30 years. Brandon is Professor of Sustainable Development in Energy at the Department of Earth Science and Engineering, at Imperial College London; Chair of the Sustainable Gas Institute; a Fellow of the Royal Academy of Engineering; and a Fellow of the Royal Society. He was additionally Director of The Hydrogen and Fuel Cell Research Hub. Brandon co-founded two start-ups: Ceres Power, which develops fuel cell and electrolyser technology based on a unique metal-supported solid oxide cell technology; and RFC Power, which develops a liquid-gas flow battery to store renewable power. Excerpts from an interview in which he offers a realistic appraisal of the possibility of channelling hydrogen for decarbonisation.

What are the most exciting developments in the field of hydrogen and hydrogen fuel cell vehicles (FCVs)?

There have been waves of enthusiasm for hydrogen before, but at the time, the world didn't really need a low-carbon energy carrier like hydrogen. The difference now is that the world needs a low-carbon molecule to support low-carbon electricity. The most exciting thing is the important role hydrogen and its carriers will play in decarbonisation. It won't be a 'hydrogen economy', but it will be 'hydrogen in the economy'.

On hydrogen fuel cell vehicles, the exciting opportunities today are not in light-duty vehicles – battery-electric is rather good at that – but in heavy-duty vehicles, and in non-road transport applications – for maritime interests, aircraft, hydrogen trains. In Europe, we're trying to replace diesel-electric with hydrogen fuel cell electric on non-electrified lines. There is a large segment of the transport sector where hydrogen or its carriers could play an important role, where battery-electric will find it difficult.

But hydrogen is more expensive than traditional fuels...

Today, we produce hydrogen from natural gas and coal. It has a high carbon footprint. We're talking about producing hydrogen with a low to zero carbon footprint: 'blue hydrogen', made from natural gas with carbon capture. That will always be more expensive. We have to recognise its benefits and incentivise that, like many low-carbon technologies were incentivised in their early days.

The other major area of interest is green hydrogen, made from renewable power (solar or wind, typically), with electrolysis. I was very interested to read about the new Indian hydrogen strategy. Since the efficiency of currently mature technology for an electrolyser is about 65-70%, hydrogen per unit of energy costs more than electricity. High-temperature electrolysers can approach 100% efficiency, but these are not mature currently.

If you can use electricity, you should: it'll be cheaper. If you can't use electricity... you need to make a molecule, and the simplest molecule to make is hydrogen.

The cost of electricity makes up 60-80% of the cost of green hydrogen today. To lower the cost, you need cheap renewable power or more efficient electrolysers. High-temperature electrolysis is over 90% efficient. There are technologies being evolved, which use an alkaline membrane electrolyser, but these are not yet commercially mature. There is potential for lowering the cost of the electrolysis, but it's always going to be dominated by the electricity cost.

How soon will these technologies be widely adopted?

If we're talking about the emergent technologies of high-temperature solid oxide electrolysis or alkaline membrane, companies are making units at a demonstration stage today. So, if things go well, let's say five years away for both of these technologies.

Can hydrogen FCVs operate in very hot regions like India and very cold places like northern Europe?

There's been a lot of work done, mainly from vehicle manufacturers Hyundai and Toyota, and light-duty vehicles can work across the full temperature range: from 40^°C to –30^°C. That's been done through some clever system engineering. These vehicles use polymer electrolyte membrane (PEM) fuel cells, and they were freezing in very cold temperatures. But some nice work was done on ensuring that water is not retained when they shut down so it doesn't freeze.

The challenge at high temperatures relates to how you ensure that everything is humidified and cooled when your external temperatures are 40^°C and your internal temperatures are 100^°C. Again, system design fixed it with radiators and a heat exchanger.

What would be the environmental impact of the production, storage and use of blue and green hydrogen?

Hydrogen itself has a global warming potential, about a third of that of methane. Also, it has safety implications because hydrogen is highly flammable. We also need to be aware of the materials used to manufacture components. In a classical PEM electrolyser, platinum and iridium are used. Iridium is very rare. You need to ensure that there is a circular economy around the materials for all the components of making, storing, and using hydrogen.

Blue hydrogen is made from natural gas, and there is an environmental footprint in the production and distribution of the natural gas as well as a residual carbon emission associated with the hydrogen itself. You're perhaps recovering 96-98% of the CO₂. Blue hydrogen is not zero carbon; it is low carbon.

There are environmental and material impacts relevant to all devices, but these technologies are quite clean. The benefit of fuel cells running on hydrogen is that they don't produce any emissions like particulates or nitrous oxides.

There have been instances of battery-electric scooters catching fire. How safe is hydrogen storage at the end-user level?

Hydrogen vehicles have been on the roads for some time now, so it is possible to create safe systems that are crash-resistant.

If a hydrogen tank is ruptured, hydrogen – which is lighter than air – will disperse as long as you're outdoors. Whereas if a gasoline tank is punctured, the gasoline forms a liquid pool, which then leads to a vapour explosion. The bigger hazard for hydrogen is in an indoor environment. The hydrogen will rise and gather in the roof void and risk forming an explosive mixture. So, in an indoor garage or in tunnels, you'd need to create ventilation for hydrogen to get out and limit explosive risk. The most expensive part of a hydrogen fuel cell car today is the hydrogen tank: an aerospace-grade tank in an automotive setting.

How best can a sustainable hydrogen economy be developed?

We're still in relatively early days. The lithium-ion battery is made at a global scale and we've seen the cost-benefit of that. While things are commercially available, none of the (hydrogen) technologies we're talking about is yet made at a global scale. So, there's a manufacturing opportunity there. Markets are global as well. At the research level, there is pre-competitive research and development across institutions. We also need to create a trained workforce at all levels to service this industry. We're a long way from having a mature sector, and will need significant investment.

What areas are important for pre-competitive research related to hydrogen and FCVs?

We need to look at the whole value chain: how we produce hydrogen, how we move it around, how we store it, and how we use it. There are pre-competitive questions right across that landscape.

Hydrogen is a small molecule that can get inside metals and create mechanical challenges. So, we need to better understand the impact of hydrogen on the materials that are used to contain and store it; and we need to continue to search for replacements for precious metal catalysts.

The other type of work would be around trying to develop models to understand how hydrogen can be used most effectively alongside low-carbon electricity. The tools and methods would be pre-competitive at the application stage because these answer national questions. An answer in India would not be the same as an answer in the U.K., but the tools we use might be the same.

Skills training is pretty pre-competitive from an educational dimension, both at the highest level and at the more vocational level with technicians, maintenance engineers and so on.

What potential do you see for investors and entrepreneurs in this space?

I've founded two companies in the hydrogen space; they're both spin-offs from the university. They're both examples that innovation and research can create new ideas that open up the possibility of building new businesses.

There are also opportunities for companies interested in the integration of technologies. If hydrogen is to become a meaningful contributor to the energy transition, that's going to be a very significant market. And opportunities for entrepreneurs who can spot the right gap, and opportunities for organisations and companies to take advantage of that.

This whole space needs investment in manufacturing. So, it's not just around the innovation and the technology, but the ability to develop devices at scale and manufacture at volume. We need that to develop a credible supply chain.

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