Hydrogen fuel cell vehicles: 10 Popular Questions Answered
Published: 11 Jan 2013
As hydrogen fuelled cars move from concept to reality, more and more people want to know more about what’s being seen by many as the ‘vehicle of the future’. Here are answers to some of the most popular questions.
Q1 When will hydrogen fuel cell vehicles be available for general purchase?
With a number of major car manufacturers already well into the development phase of hydrogen powered models, we should start seeing them on our roads within a decade.
Q2 Are hydrogen fuel cell cars better than their battery powered electric equivalents?
The key advantages of fuel cell electric vehicles (FCEV) over battery electric vehicles (BEVs) are that they can travel further and they take less time to refuel. Another advantage is that they don’t have to carry the batteries that add more weight to BEVs, which would reduce their efficiency.
Q3 Is it more efficient to use electricity to charge a BEV than electrolyse water to produce hydrogen for fuel?
No. The process of electrolysis of water is 75 per cent efficient compared to producing electricity from natural gas which is 49 per cent efficient.
Q4 Is there room for both BEVs and FCEVs on our roads? Shouldn’t we just focus on one technology?
The two can happily exist together because BEVs are great for short-range use, while FCEVs are the green and practical solution for driving longer distances.
Q5 From a ‘well to wheel’ emission standpoint, how do FCEVs compare with diesel cars?
Assuming that the diesel is from refined oil, a direct injection internal combustion engine (ICE) is used, and that the hydrogen is created by hot steam reforming (the most usual process for producing hydrogen), then the FCEV would reduce CO2 equivalent emissions by approximately 30%. If the hydrogen came from electrolysis that was powered by renewable electricity, the reduction would be over 90%.
Q6 Micro beads that capture hydrogen have been suggested as a potential fuel source, would they work?
There are a number of current issues such as how quickly hydrogen can be absorbed and released from micro beads, as well as logistical issues of transporting charged beads to where they’re needed and then the discharged beads to where they can be recharged. Therefore it is unlikely that they will displace gaseous hydrogen storage in the medium-term.
Q7 If a hydrogen distribution infrastructure was in place, could it be used to fuel traditional internal combustion engines as well?
Some manufacturers have converted internal combustion engines (ICE) to run on hydrogen, but with the costs of the various technologies converging, little would be gained by doing so.
Q8 Metals become brittle after exposure to hydrogen, isn’t this a problem for manufacturers?
Such ‘hydrogen embrittlement’ affects certain metals, most particularly high strength steels at high pressure, so the simple solution to this problem is to use suitable materials that aren’t affected in the high pressure sections of the system.
Q9 From a safety perspective isn’t it better to carry water in the car that can then be electrolysed to produce hydrogen rather than storing hydrogen itself on board?
The main practical problem with in-car electrolysis is that it would be difficult to incorporate the volume and weight of hydrogen generation equipment needed into a car in the first place.
Q10 Are there safety issues when a car carrying hydrogen is involved in an accident?
Hydrogen is safer to store in a car than either petrol or diesel for three reasons. Firstly, the hydrogen storage tank is much more robust than one for conventional fuels and is therefore less likely to rupture in the event of an accident. Secondly, hydrogen is a gaseous fuel which means that no combustible mixing of fuel and air ever occurs. And thirdly, should hydrogen escape it rises, unlike petrol or diesel which can leak and pool beneath a vehicle.
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