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Toyota Mirai FCV Concept

Toyota Mirai FCV Concept

Elon Musk is famous for referring to fuel cells as fool cells, as that name suggests he doesn’t think much of the technology, at least not for cars. But is he right or is he just naturally trying to bolster the position of EVs, something he is heavily invested in through Tesla?

Fuel cells have been referred to as the future of automotive technology for as long as I can remember, but they seem to be taking a long time to become a reality on our roads. In the next few years however Toyota and a number of other auto manufacturers are going to start selling and leasing fuel cell powered vehicles to members of the public. Does this mean that hydrogen vehicles powered by fuel cells are about to finally fulfil the promise of emission free driving in a way that electric vehicles have to yet to achieve?

I seriously doubt it! Let’s look at some of the facts behind fuel cells and how they compare to battery electric vehicles.

Firstly filling time, this has to be the one single biggest problem that people see with EVs at the moment, even more so than limited range. Batteries take time to charge, there is no way round it. Although a modern EV can charge hundreds of miles worth of range in an hour, it can’t put in that range in a few minutes and probably never will be able to, the amounts of power are simply too huge. For example, in order to fill a Tesla Model S battery to 90% in five minutes it would require a power feed of approximately 1 MW, that’s enough power to run an entire village, just to refill a single car! Fuel cell vehicles however can be filled with hydrogen in 5-10 minutes, depending on who you ask (and what pressure the hydrogen is delivered). So that’s a clear win for fuel cells then isn’t?

Well it is not quite that simple. An EV will start every day with a full battery, so for average errand/commutting days there should be no need to charge at all away from home. This means that the infrastructure for recharging EVs can be concentrated out of town on motorways and other major trunk routes. These rapid chargers are also considerably cheaper to install than a hydrogen filling station. On the other hand the fuel cell car is going to need to make a dedicated stop to refill with hydrogen every few days, that means that the hydrogen filling stations will need to be fairly close to home for those drivers, after all how would you feel about driving 40 miles just to refill your car?

Then we come to range, that at least is a win for fuel cells isn’t?

Again, it’s not quite that simple. Yes most current generation EVs have a range of around 100 miles, certainly a lot less that the 200 to 350 mile range for fuel cell cars (Toyota claim a 400 mile range for the Mirai, but then Nissan claim 124 miles for the Leaf and on the same test cycle the Model S 85 claims 310 miles, none of these figures are achievable in the real world). However that is just current generation EVs and not all of them at that. The Tesla Model S with the 85kW battery has a range that is not far off the Toyota Mirai fuel cell car that goes on sale later this year in California. The price is not particularly different between these two cars either.

The probem with range is that lithium based batteries are still nowhere near their theoretical capacity limit. It is entirely possible to cram enough energy (and lithium) into a battery the same size and weight as the one in the Model S, to drive 1,000+ miles on a charge. Obviously we are not there yet and may never get there, but 500 miles is probably achievable in relatively short order.

Hydrogen on the other hand has a problem. The stuff has very low density, high energy yes, low weight yes, but very low density. So in order to put a sensible amount into a car you need to compress it to huge pressures. The Toyota Mirai stores its hydrogen at 10,000 PSI! Why’s that a problem you ask? Well you can’t just keep on compressing things, material limitations come into play fairly quickly. If we could produce hydrogen tanks that fit in cars and can store hydrogen at 100,000 PSI, then we’d also be able to make bullet proof tissue paper!

So EVs are likely to outstrip fuel cells in range in the not too distant future, that’s my prediction.

Probably the biggest economic hurdle for fuel cells is that of infrastructure. Here the problem is that a hydrogen filling pump costs 10x the cost of an EV quick charger, but as we’ve discussed earlier you’d need far more of them, because poeple would need them out on the open road as well as close to their home. This means that the investment required to get a hydrogen refilling infrastructure off the ground would be enormous compared the bargin basement setup of EV quick chargers.

The last problem with fuel cells is the fuel itself. It takes roughly twice to three times as much energy to drive the same distance down the road in a fuel cell car as it does in an EV (because electrolysis used to produce hydrogen is very inefficient). This means that when all the funky subsidies and introductory offers from manufacturers are over, you’ll have to pay twice as much for fuel as you would have had to in an EV. Yes I know 98% of hydrogen at the moment comes from natural gas reformation, but that is a fossil fuel and producing hydrogen from it creates CO2, so that’s not going to help much in the long term. Oh did I mention that hydrogen leaks slowly out of anything and burns with an invisible flame? Sounds safe doesn’t it!

In conclusion I wouldn’t hold my breath for fuel cell propelled vehicles any time soon. If you want to drive a fast, responsive, smooth, zero emission vehicle, get an EV and if you really want to help the environment put solar panels on your roof to power it.

  
        
          

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