Many time in the past decade we have heard how hydrogen (H2) could be used in transportation to bring about clean transportation with great performances. It often comes back in the press through news of advances realised on storage. Advances that are supposedly going to save the whole idea and bring about a revolution in motoring within the next few years (latest example as of 2011).
Here at CityVolt, we considered the question long and hard, but unfortunately we realised there is little to this claim, even if it has made a very strong impression in the public’s mind. Here is why we does not believe in hydrogen as a public solution for mass transportation.
To begin with, it must be made clear that when we talk about hydrogen, it is as a medium to store power for use in a fuel cell to produce electricity (more later). When used directly as a fuel source in thermal engines (internal combustion engines), it has a poor power output. BMW is famous for having tried to develop this solution for a long time, and their results were plainly bad. Not only the costs per vehicle were high (the whole apparatus was awfully complex) but the results were also poor: 180hp out of a 4.2L V8, or 260hp out of a 6L V12!
For hydrogen to have even a standing chance in transportation, it needs to be used through a fuel cell to produce electricity fed into an electric motor. The whole oxydation process that leads in hydrogen being transformed in water and oxygen is well explained on wikipedia.
While this idea has advantages similar to traditional fuels that still eludes full-electric car, such as longer autonomy and refuelling speed, it suffers from systemic issues that cripples it in reality.
First and foremost, how to produce hydrogen? There are chemical reactions that can produce hydrogen, but these reactions use fossil fuels and their by-products are almost as polluting as burning traditional fuels. The only way out of this is to produce H2 by electrolysis. That is decomposing water in its two base elements, O2 and H2, by running an electric current between two electrodes (to put it simply).
While electrolysis makes sense from a practical point of view, it requires large amount of electrical power to be achieved. And during this process a large share of that energy is wasted in heat (30 to 50% in laboratory conditions, probably more in real conditions). To rephrase this more simply: You’re already losing 50% of your power in producing H2 by electrolysis.
If we were however to do away with this issues and consider hydrogen as a practical solution, we would need centralised production facilities, for reasons of efficiency, scale and cost.
This raises a second issue: How to transport hydrogen?
This would call for a complete redesign of our fuel infrastructure, and as every EV stakeholders has painfully learned, infrastructure usually means “large expenditure”. Obviously, an hydrogen infrastructure cannot be done on the cheap since a catastrophe “Hindenburg Style” would sign the death warrant of the industry. There has been different estimates floated since the idea encompasses a head-turning number of parameters and actors, but the number often quoted for a small network in the US is 500 billions USD (research done by the Argonne National Laboratory). However wilder figures going into the trillions of USD have also been suggested to convert the entire petrol infrastructure in North America. The numbers are staggering and calling for a simple question: Is this worth it?
Proponents of H2 often do away with this issue by urging people to act in the face of global warming, considering that the only alternative to fossil fuels is H2 fuel cells. But it is not, and we believe clean transportation can be done cheaper and simpler.
Further to this infrastructure issue comes the problem of efficiency at compression. To transport H2, you need to compress it. Indeed hydrogen atoms are so small in size, that they can go through most materials, thus making the gas unfit to be pipped in traditional pipeline at normal pressure (it leaks out of the steel). To compress and liquefy it you need to spend a large amount of power that is mostly wasted in heat (it’s also why your bicycle pump becomes warm as you inflate your tires).
Storing hydrogen cheaply and conveniently in a car is also yet undone. Hydrogen as a gas at normal density has a lower power density when compared to gasoline. This means you need to compress it to store several kilos of it in a tank to get enough autonomy in a vehicle. But because of its physical properties, hydrogen can leak through most materials. This means tanks need to be made of special materials, and are thus both bulky and expensive. It is likely however that this issue will be solved at some point in the near future, thanks to relentless R&D done on the topic around the world.
Beyond these issues comes the simple transformation of H2 into water and electricity in the vehicle. Fuel cells requires precious materials such as platinum (1500USD of it alone for a cell big enough to power a car) and while research is being done to improve both cost, performance, and size, fuel cells still a far cry away from being ready to be implanted in a car.
According to our conversations with the leader of the team working on the Formoto, a hydrogen fuel cell scooter from the Formosun Advanced Power Research Center at the National Taiwan University, the technology of the fuel cell is still 20 to 30 years away from being ready for mass production.
This lead to several other questions of integration on an industrial level: Will car makers accept to gamble on a unproven technology? How will H2 be stored in cars? What about the fuel cell? How will this impact the design of vehicles?
This is obviously a difficult call for an industry as conservative as the car industry when retail prices risk being far higher than usual.
To develop these practical considerations in other terms, let’s consider the suggestions often floated by H2 supporters as the “Graal of hydrogen design” that would solve all problems: That of wind turbines producing directly H2 for transportation use. Following their argument this would mean abundant and clean energy from a free resource. However this idea is plagued with several issues:
- The wind blows in one place, the consumer wants to fill his tank somewhere else (Infrastructure)
- The wind blows… or not. Consumer still want to use his vehicle (Production)
- What is being done with the hydrogen produced onsite (Storage)
- Will consumer buy a 50 000USD Camry “just because it’s cleaner”? (Retail Price)
To conclude, the most damning problem of H2 in transportation is that of the poor overall efficiency. From the plant to the wheel, using H2 for propulsion has an efficiency of 17 to 22%. This compares to 76% for an electric car. A car that would actually retail for cheaper.
So here is the big question about hydrogen: Can we really afford to waste 4 times more energy, and pay twice as much for cars, just to feed our tanks with “something that sounds cool” ?