Tuesday, February 17, 2009

Hydrogen fueled cars

On the Register today they're talking the LA Times talking about the Honda FX Clarity, (also on wikipedia and Top Gear's site) the first commercially available (albeit only in Southern California) hydrogen fuel cell driven car.

Top Gear did a great piece on this car just before Christmas. James May loved it, he waxed lyrical about it, they even got Jay Leno to say how much he loved it too - though his comments focused more on how it was going to save his beloved petrol-drinking race cars by allowing the petrol to last longer.

Now Dan Neil (who?) writing for the LA Times writes off the hydrogen fuel cell idea as a cul-de-sac in development. Just because there's no network of hydrogen filling stations outside of Southern California. I beg to differ mate. There's a massive, coordinated, reasonably resilient network of filling stations already out there. All we need to do is persuade them to carry one more product: liquid hydrogen. I'll come back to this later.

Ok, let's step back one moment and look at why we would want to use hydrogen over batteries first of all. The only car remotely comparable to the FCX Clarity is the Tesla Roadster. Fast, good looking (based on the Lotus Elise), and run on batteries. Tesla claim a range of 220 miles on a full charge, as opposed to Honda's claim of 270 miles on a full tank of hydrogen. The Tesla is a two-seater; the Honda a family saloon (Dan Neil says, "Lincoln-Town-Car huge, and the trunk is a spacious 11 cubic feet."). The Tesla has a huge composite battery made of 6,831 lithium cells (essentially laptop batteries!). Yes six thousand, eight hundred and thirty one of them. Imagine how much that must weigh (actually, it's 450kg). No wonder there's no room for passengers!

Top Gear's analysis basically went along the lines of, the Honda is going to succeed because it is so much like what it replaces ... the normal, standard, family saloon of today. No big leap in behaviour for the motorist, no big change in the experience of car travel, just an enormous change in the type of fuel and emissions.

Finally, on the cars themselves. The Honda is made by ... Honda. One of the world's largest (if not the largest) car companies. The other by Tesla Motors... who? Even if they are backed by Elon Musk, co-founder of Paypal, that's an awfully long way from the scale of Honda.

Now, back to the choice of fuel. It is clear that producing liquid hydrogen takes about four times more energy than the Tesla needs for the same range:
  • Tesla: 53kWh for 220 miles
  • Honda: 240kWh for 270 miles worth of hydrogen, (or 195kWh for 220 miles to match the Tesla's maximum range)
But the big difference is in the behaviour required to support the difference. With the Honda you go to the fueling station and fill up the 4kg tank when you run low. It takes a couple of minutes, just like a conventional petrol tank. With the Tesla, you plug it in every time it runs low ... for three and a half hours (!) at 240v (great if you're on 120v in the USA). So where do I plug it in if I have no garage, or if my parking space is some distance from my home? 

See what I mean about changes of behaviour?

Finally, back to Dan Neil's biggest complaint; that there is no network of hydrogen fuel stations. This could be solved reasonably simply by the simple expedient of mandating any new fuel station must install and maintain at least one hydrogen pump, similarly any existing station wanting planning permission for changes must install and maintain a pump, and every other existing station has two years to install at least one, with increasing penalties for every quarter thereafter when they don't have one.

By that simple change, the suppliers have a distribution network, where the cost is widely distributed (maybe the local or federal/national government can give a subsidy to sweeten the deal if they install more than one at a station), and the car manufacturers have the opportunity to sell new cars all over the place. Consumers would finally have a real choice that makes the possibility of switching away from oil a real, practical and most of all normal change. Just change the pump you visit on the forecourt - just like going unleaded or diesel.

With a company the scale of Honda behind the FCX Clarity, they could easily ramp up production to meet demand were the pumps available, and that demand would just as easily justify the investment in the pumps and infrastructure. Not just a win-win, but a win-win-win-win: car manufacturers, fuel distributors, consumers and the global environment.

Update: a number of commenters on the original Register article have been talking about using replaceable batteries, rather than charging up your own battery. Given the sheer size of the Tesla battery (which seems to be what you need to get a sensible range out of an electric car) and weight of it (450kg), the idea of a filling station (or equivalent) storing hundreds (possibly thousands) or batteries fully charged, and transporting said heavy objects around the place every day (or charging them on site - imagine the electricity supply required to do that - 70 amps for 3.5 hours per battery), doesn't strike me as being in the least bit practical. And how do you propose a driver in poor health, or not built like Arnold Schwartzenegger is going to handle swapping over batteries like that? You might as well suggest that the hydrogen fuel tank of the FCX Clarity is swapped out every time, instead of filling it with liquid hydrogen.

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