Hydrogen, fuel of the future ?
An interview with Professor Jan Van Herle
Electric cars have been highly successful, and they don’t emit CO 2. So, what’s the use of exploring an alternative solution ? This was the naive question addressed to Jan Van Herle, an expert in electrolyses and fuel cells, researcher, and professor at the École polytechnique fédérale de Lausanne (Swiss Federal Institute of Technology Lausanne).
Professor Van Herle, aren’t electric cars sufficient for clean mobility ?
Jan Van Herle : Current electric batteries are not the perfect solution. Their repeated charging and discharging cycles negatively impact their durability. Besides, recharging takes too long, which is not practical for the users. Their weight increases proportionately with the required autonomy and so you quickly reach a limit : it is hardly efficient to embark battery weighing several hundreds of kilos, part of which will never be used. Moreover, lithium resources are limited and will end up lacking. The use of hydrogen would mitigate some of these problems.
By doing exactly what is already being done in hydrogen cars : replacing part of the heavy electric battery – storing electricity – with a fuel cell and a hydrogen tank – that will produce electricity. The cell is the main source of energy, the battery provides power – acceleration, and driving dynamics. A combination of the two provides a lighter solution with twice or three times as much autonomy, depending on the case. It also increases the battery’s lifespan since the fuel cell keeps it in a reasonable charge status – avoiding deep discharge. It’s a win-win solution.
What is the fuel cell/battery proportion ?
Manufacturers adapt the proportion according to their intentions. Typically, it is fifty-fifty. A Hyundai Nexo is an almost purely hydrogen car : it has a battery, but it is the 5 kg of H 2 on board that drives it over 500 km.
The solution is still in its early days, is it performing enough ?
Over the last few years, research and strong investment in the car industry have contributed to greatly enhancing their performance.
We can see the progress for example in their power density – the kilowatts produced in relation to the cell volume. In the beginning, it was around 0.5 kW/l. Then it reached 1 kW/l. Today, in mass production, the Toyota Mirai 2 is at 5 kW/l. Some companies have designed cells that provide 8 kW/l. So, cells have become highly compact, and their performance is rather impressive.
How about the price ? A hydrogen car is much more expensive than an electric car…
This is probably the main obstacle to their widespread adoption by the public. Some of the materials used in fuel cells are costly. Platinum, used as a catalyser is expensive, but it is used in smaller and smaller quantities. The polymer of the membrane is not cheap either. Bipolar plates are made of graphite, coated steel, or Titan.
The latter is expensive. Moreover, it needs to be protected against corrosion in an acid environment. However, all these costs depend on production volumes. Thermal engines, composed of thousands of components, are also costly to start with. But, since they are mass-produced in 70 million copies a year, the price goes down to 50 euros per kW. If the same tendency applies to PEM fuel cells, their price will also drop.
There is a strong increase in hydrogen vehicles. However, when we compare their numbers with all car categories, they are paltry : 60,000 on the road, 1,000 filling stations planned in Europe by 2030…
Clearly, we are only at the very beginning. Manufacturers invest with prudence, evaluate the demand, and move forward step by step. Infrastructure also needs to be developed.
… especially that it is not possible to charge one’s car “ at home ” like an electric car.
In theory, it should be possible. Nicolas Hayek, late CEO of the Swatch Group (and initiator of the Smart micro-car) imagined that houses could have an electrolyser powered by solar panels. It is technically possible, but too expensive and complicated from a safety point of view.
So, filling stations should be multiplied…
… which is also expensive. But again, unit prices will drop with increasing quantities. Note that the number of stations is not necessarily a limiting factor : there is no need to have that many to guarantee the rise of hydrogen cars. Once it starts, progress may be rapid.
Further upstream, there is the problem of the origin of the hydrogen used. Currently, 95% of its production comes from fossil energy, which ruins the very idea of “ clean vehicles ”…
For mobility, green hydrogen is a must, otherwise, it makes no sense. The proportion you mention can be explained by the current dominant use of hydrogen : heavy industry. It is used to produce ammonia (an essential component of fertilisers), to produce methanol, to remove sulphur from oil and to create value-added petroleum products. These are large-scale uses, and the hydrogen is derived from fossil fuels because they are the cheapest. By extracting it from natural gas, coal or, in the case of the petrol industry, from petrol itself, it costs 1-2 euros a kilo.
So how can green hydrogen be produced ?
By electrolysis of water using energy from renewable sources - pho-
tovoltaic, wind, hydro...
Is this feasible on a large scale ?
The world, and Europe in particular, is engaging huge resources in energy transition, of which solar and wind power are the pillars.
Hydrogen is part of this effort because it offers a solution to the problem of storing renewable energy.
For example ?
We can’t “ store ” the excess electricity produced by a 2 MW wind turbine in the electricity grid, but we can put an electrolyser at the foot of the wind turbine, which will use electricity to produce hydrogen, which can then be stored and used later. We still need to improve the various solutions for storing and transporting H2, which represents a heavy weight in the overall energy balance of this solution. However, scientists and politicians are pushing for large electrolysis capacities. Gigafactories of electrolysers are being considered to capture green energy and transform it into hydrogen...
.. which vehicles can then use.
Exactly. The development of (large) hydrogen-powered vehicles is part of the energy transition. They are benefiting from its progress and are being driven by it.
What is required to boost this development even further ? Technological innovation or policy ?
Both. A transition of this kind can’t happen without strong political will. Technologically speaking, nothing is ever finished : the combustion engine has been around for 150 years, and billions are still injected every year to improve it... For fuel cells, we need to find ways of reducing the use of platinum. Because it’s expensive, limited, polluting to extract and fragile to source (90% in South Africa, with Russia in the second place...).
In conclusion, what is your vision of the future of hydrogen-powered vehicles ? Will they become dominant ?
No, they won’t. They will coexist with various complementary solutions. Electric batteries seem to be the best solution for light vehicles - bicycles, motorbikes, cars, etc. Fuel cells for heavier vehicles - commercial vehicles, lorries, boats, trains, etc. For very heavy vehicles and for covering large distances (crossing an ocean, etc.), fuel cells pose a storage problem, so liquid fuels will be used because their energy density is better. Ammonia and methanol are being considered, and we need hydrogen to produce them ! Green mobility will need all these technologies.