This is the second in a short series of articles that will culminate on Halloween, in which we present four zombie technologies that display zombie characteristics
We’ve all seen it: great new technologies with huge potential from a central promise to revolutionize what we do. However, each comes with a challenging list of problems that — when viewed objectively — relegate the technology to prototype form with limited commercial value. These problems could include available technology, cost, business model, and in some cases, the basic laws of physics.
However, these problems aren’t enough to stop hardy groups of individuals from continuing their development and promotion, fuelled by the promise of fulfilling those technologies’ potential.
Zombie Technology 2: Hydrogen fuel cell cars
Emissions-free driving, using a fuel made from water using excess solar and wind electricity. We refuel in minutes at a “gas station” just like we do today, with a range per fill about the same as a typical gas engine car. What’s not to like?
How it works
The H2 (hydrogen molecule) dream being pitched is that we soon will make renewable electricity in abundance — way more of it during parts of the day than we need. We could use that excess to generate hydrogen from water at a fuelling station. The hydrogen will be stored onboard the vehicle as a high-pressure gas, which is fed to a fuel cell — a type of flow battery where hydrogen reacts with oxygen from the air, with the resulting flow of electrons being used to run an electric motor.
Why it should die (or how it could live)
The idea is a seductive one and has received a great deal of support from Asian OEMs such as Toyota, Honda and Hyundai. But sadly, the devil is in the details.
Today, hydrogen is used in massive quantities around the world as an industrial gas, and 96% of it is made from fossil fuels, with consequent CO2 and other emissions entering the atmosphere. The hydrogen process involves three steps: making hydrogen, storing and distributing it, then producing electricity again in a fuel cell. Each step loses energy — and not just a little. Best-case efficiencies are approximately 70% for electrolysis (separating water into hydrogen and oxygen), 90% for high-pressure storage, and 60% for the fuel cell. For every kWh fed to the electrolyzer, just 0.37 kWh (or less) comes back out of the fuel cell. Thus, through this process, most of the energy is lost. In contrast, a lithium ion vehicle battery gives back about 90% of the electricity it is fed. Those H2 limits are mostly thermodynamic, or natural laws of physics, so we’re unlikely to see significant improvements with new inventions. Energy is never free, and always comes with an environmental impact. Hydrogen’s inefficiency makes it a very expensive fuel in terms of both cost and the environment.
Hydrogen also takes up a lot of space. Even at 10,000 psig (pounds per square inch, gauge) — 700 times the pressure of the atmosphere — hydrogen is still only 42 kg/m3. That low density makes it hard and expensive to store and distribute. The hazards of a flammable, high pressure gas mean that refuelling must be tightly controlled, eliminating any ability to refuel at home, like you would for an electric vehicle.
Then there’s the vehicle. A fuel-cell car contains every part that an EV contains — including a smaller EV battery — plus the fuel cell and hydrogen systems.
The problems with hydrogen as a vehicle fuel become most stark when you compare two cars you can buy today: the Toyota Mirai FCEV and the Tesla Model 3 long range BEV. While both cars have roughly a 300-mile (500 kilometre) range, the Mirai is heavier, more expensive, much slower, uses 3.2 times as much energy per mile and costs at least 5.4 times as much per mile driven. This calculation is done where the hydrogen used is only one-third renewable and two-thirds cheaper fossil-sourced hydrogen. That’s a very hefty price to pay for faster refuelling — assuming there’s a hydrogen station along your route (a very big “if”).
Clearly H2’s potential for vehicles and most land-based transportation is limited. However, due to hydrogen’s energy density advantages over lithium ion batteries when used for long distances, there may be potential for usage in long range transportation, such as trains, shipping and possibly ultra-long-haul trucking.
Today, less than 1% of hydrogen is made from renewable resources, and the excess renewable hydrogen that people think we’ll be fuelling their cars with, just doesn’t exist — and will not exist until a significant and sustained carbon tax is applied. Even if we do see lots of hydrogen being generated one day from renewable electricity, directly using that electricity in an EV instead will still have a huge cost advantage. That advantage arises from basic physics and chemistry, which is why the H2 dream will continue to struggle.
Our Halloween conclusion
H2 has some potential narrow use cases for long-distance transportation, but it’s a waste of time for your car.
In this series
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Paul Martin is a chemical engineer, and lifelong environmentalist. He’s a passionate advocate for electric vehicles (he built one himself), and a renewable energy advocate. He has spent 23 years at Zeton Inc. designing and building pilot and demonstration plants for the chemical process industry, helping clients bring new chemical process technology to market.