Jan 6
Hydrogen fuel cells in transport
Cars and beyond
What is a hydrogen fuel cell?
The simplest explanation: Hydrogen Fuel cells are boxes where hydrogen converts into electric energy and water as a waste product. And when I say boxes, I mean it. See figure 1:
Why are hydrogen fuel cells so boxy?
Because fuel cells are straightforward devices in their making, stacking a few plates and proceeding to box them (figure 2).
How do fuel cells compare to a battery in performance?
It depends on what kind of performance you measure and need. Figure 3 compares the energy and power density of different energy storage technologies, including fuel cells.
Energy density means how much energy it can store. In a car, that would equate roughly to drive range. Power density means how fast it can release energy. In a car context, this would be useful in acceleration and torque.
Fuel cells display great energy density and lower power density compared to batteries.
If fuel cells work for cars, why are so few hydrogen cars?
If you ask most experts, they will tell you that fuel cell hydrogen cars and trucks are doomed. At best, there may be fuel-cell ships and airplanes. They will point to how few hydrogen cars exist on the streets, how few models of hydrogen cars are available, and how there is a lack of hydrogen refilling stations.
They will add that most hydrogen is grey hydrogen, thus carbon emitting and dependent on natural gas when there is a drive for supply chain security.
Fuel cells work, and there will be more hydrogen cars
Several sources of green hydrogen are already available, some at competitive prices. Its price will further decline as demand for green hydrogen and renewable energy cost continues to decrease.
Hydrogen fuel cell cars perform much better in cold conditions and display large drive ranges and quick fill times. The lack of hydrogen fuel stations that hold fuel cell car adoption is rolling back.
Lithium is scarce and depends too much on China
On the other hand, critics can point out problems with lithium supply, including future lack of it. Lithium deposits are much more concentrated than hydrogen.
Furthermore, lithium refining concentrates in China at a scale much more extensive than any fossil fuel. And will remain so in the following years.
Hydrogen production is more supply-chain friendly.
We can always make hydrogen from water via electrolyzers. It does have to be drinkable water: seawater or brackish water will do.
Electrolyzers are also a simpler technology to decentralize compared with refining lithium. You can make electrolyzers at different capacities, from the kW to the MW.
Finally, if you use seawater or brackish water, you can even mine lithium while treating the water for electrolysis.
Hydrogen production fits renewable generation.
Future hydrogen will be green-sourced with renewable energy at periods of excess energy production, reducing energy curtailment.
Fast refilling favors hydrogen in work vehicles.
One sector embracing hydrogen is work vehicles. Toyota sells hydrogen forklifts amongst other companies. Walmart has used hydrogen forklifts since 2012.
Walmarts supplier, Plug Power, leveraged their ten years of partnership in 2022 to also supply green hydrogen.
At the same time, Plug power is expanding its partnerships with Amazon, Home Depot, South Korean SK Group, and car companies like Stellantis and Renault.
Fuel cell technology also allows for retrofitting from fossil fuel, turning diesel excavators into hydrogen-powered ones.
Cargo range favors hydrogen trucks
Fuel cell hydrogen trucks display an advantage over battery-electric trucks on the cargo drive range. See figure 4
This advantage propels several investments in fuel-cell trucks:
- US companies like Cummins, Kenworth Trucks, and upstarts like Nikola and Hyzon Motors;
- European joint ventures like Cellcentric (Daimler and Volvo) and Symbio (initially, Faurecia and Michelin, with Stellantis negotiating to buy in);
- Japanese offshoot Hino Trucks a Toyota company;
- South Korea Hyundai
- Several Chinese companies like Beiqi Foton and Foshan Feichi Bus, although the main focus targets buses, Foshan Feichi recently announced a heavy-duty fuel cell autonomous truck.
A North American Council for Freight Efficiency report, fuel cell hydrogen competitiveness will increase due to more investment and research. Similar studies in Europe and China predict fuel cell trucks will be competitive by 2030, heavily influenced by the cost of hydrogen.
Oh, but what about future battery technology?
Apparently, hydrogen still outperforms batteries for long haul cargo (figure 5).
Hydrogen drive trains to drive trains
Regular hydrogen train service started in Germany in 2022. India plans to begin services at the end of 2023. Regional lines, with low traffic at lower speeds and no electrification, are the target for hydrogen trains replacing diesel trains.
Shipping is turning to hydrogen for decarbonization
In ships, hydrogen fuel cells provide the best fit, with battery-powered ships relegated to niche applications in short periods and high-power cases.
A small demonstration ship equipped with fuel cells sails worldwide since 2017. Norway recently approved MF Hydra, a fuel cell ferry, for operation.
There are already several options for hydrogen fuel cell systems for boats, but they are still expensive. Hydrogen availability still needs to be improved, but generation can happen on the spot.
Airplanes flying on hydrogen
The European airplane manufacturer Airbus sees hydrogen as one of the means to achieve a zero-emission fight. The ZEROe concept presents different future implementations of hydrogen on planes.
Hydrogen fuels all three concepts. Planes without jet engines use only fuel cells to power propellers with electric motors. Planes with turbofans use fuel cells for the fans and hydrogen directly as fuel for the jet engines.
Meanwhile, experimental planes make flights to test and improve the technology.
Does hydrogen versus batteries make sense?
Finally, this may prove a false dichotomy in the future. Current electric lithium ion cars still sport a little led acid battery. Similarly, hydrogen vehicles contain a lithium battery.
Seemingly competing technologies can and should turn out complimentary. And since there are doubts about lithium availability and its refining concentration in China, hydrogen can help on both counts.
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