back to article Brits rattle tin for 'revolutionary' hydrogen-powered car

UK hydrogen-powered car outfit Riversimple is inviting investors to open their wallets and buy into what it considers to be the future of four-wheeled transport: the "revolutionary" gas-driven Rasa. A side view of the Rasa The Wales-based company unveiled its prototype Rasa (as in "tabula rasa") back in February. It claims …

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ero emissions?

And exactly how are they generating the hydrogen, transporting it, storing it etc. with 'zero emissions'?

Also, how is the hydrogen stored in the car?

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(Written by Reg staff) Gold badge

Re: ero emissions?

In the car, in a fuel cell. As for the rest of it, that's not so clear.

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Anonymous Coward

Re: zero emissions?

Have a curry just before you set off?

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Re: ero emissions?

The fuel cell is where the hydrogen is reacted, not where it is stored, unless standard terminology has deviated radically in recent times. The hydrogen will be stored in a tank.

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Re: ero emissions?

'The hydrogen will be stored in a tank.'

Well that won't help the fuel economy, Sherman or Churchill?

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Re: ero emissions?

"The hydrogen will be stored in a tank."

And that's the part which is most problematic.

The car and powertrain part are relatively easy. Storing and transporting hydrogen at extreme cyclic pressures - reliably and safely - in such a way that the equipment will last at least a decade is a not-fully-solved materials science problem.

The liabilities (and PR damage) when a hydrogen tank inevitably ruptures are such that I'm pretty sure insurers will be hesitant to provide manufacturer cover.

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Re: ero emissions?

> And exactly how are they generating the hydrogen, transporting it, storing it etc. with 'zero emissions'?

They claim "c.40gCO2/km Well-to-Wheel – even if the hydrogen comes from natural gas"

> Also, how is the hydrogen stored in the car?

There's a helpful arrow on the diagram. :-)

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Re: ero emissions?

"And that's the part which is most problematic."

No, not really. First off, the tank pressure is said to be lower than usual, around 350bar. Second, scuba tanks are routinely pressurised at similar pressure and have a life of hunderds of thousands of cycles. Third, yes I do understand that air / nitrogen / helium etc. is not the same thing as hydrogen and specific care has to be taken in the choice and engineering of the material used, but declaring that "problematic" sounds a bit loaded.

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Boffin

Re: ero emissions?

Has there even been an engineering challenge that wasn't 'problematic'?

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Re: ero emissions?

"Has there even been an engineering challenge that wasn't 'problematic'?"

Not an interesting one, no.

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Go

Re: ero emissions? DropBear

The big difference between Hydrogen and the gases normally used for diving is that hydrogen under pressure reacts chemically with the tank, causing embrittlement and rupture.

Another problem is that hydrogen has a very low calorific value compared with hydrocarbons. That means either a B****y big cylinder of gas (bulky and heavy) or store the fuel as liquid with all the fuel costs of liquifaction and allow it to slowly (over a few days) boil away. **Don't store the car in a garage at home or anywhere enclosed near me if you go down this route.**

So, with a low pressure cylinder, the range will be exactly what?

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Re: ero emissions? DropBear

"

So, with a low pressure cylinder, the range will be exactly what?

"

It states the range in the article. Not that it is likely to be any more "exact" than it is with an internal combustion engine car.

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Anonymous Coward

Re: ero emissions?

Does anyone remember the Ford Pinto and its exciting new exploding gas tank?

What do this Rasa and the Pinto have in common? Could it be fuel tanks located in the trunk area of the vehicle? Hydrogen also causes embrittlement of various metals making that "tank" anything but safe in a reaer end collision.

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Re: zero emissions?

Have a curry just before you set off?

No, that's for the methane version which won't be introduced until 2018.

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Re: ero emissions?

"Third, yes I do understand that air / nitrogen / helium etc. is not the same thing as hydrogen and specific care has to be taken in the choice and engineering of the material used, but declaring that "problematic" sounds a bit loaded."

Air/nitrogen/helium at any pressure don't cause hydrogen embrittlement (very similiar to neutron embrittlement in the nuke industry). It's bad enough in the CNG industry and the hydrogen there is generally bonded to 4 carbon atoms already (If you've ever seen a CNG tank burst you'll know how dangerous that can be - cars generally get shredded when it happens)

"Problematic" is actually an understatement and the cyclic nature of the pressurisation along with low mass requirement for transportation add an order of magnitude of complexity to the problem. https://en.wikipedia.org/wiki/Hydrogen_embrittlement

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Vic
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Re: ero emissions?

Second, scuba tanks are routinely pressurised at similar pressure and have a life of hunderds of thousands of cycles.

No, not really.

Most scuba cylinders in the UK have a working pressure of 232bar; these are pressurised to a test pressure of 348bar once every 5 years. A 30-year-old cylinder has only experienced this sort of pressure a handful of times...

There are a range of 300-bar cylinders in use; these have their own problems (not least that the gases are very much non-ideal at those pressures, so you don't get nearly as much as you thought you might[1]), Weight does become an issue...

And all this is before we get to the problems of hydrogen - others have mentioned embrittlement, I'll mention leakage...

Vic.

[1] I've just done a quick calculation using an online Van der Waal's calculator. I used a 20l cylinder blown to 350bar at 300K, which gave me 204mol H2. That much gas at 1bar gives 5100l, rather than the 7000l one might naively expect...

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Anonymous Coward

I had one of those

It came free in a box of cereal. Oh! You mean that's a real car!

Lets hope they spend some money on the design rather than use the drawings someone's 5year old produced when asked to design the car of the future - back in 1950...

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same as a family hatchback my a****

hmm, so same cost as a family hatchback but with no back seat!! what a great family car that will be

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WTF?

Company wordsmith?

WTF? Seriously WTF?

And as for it looks like a "superstar's car" I think I may have a different idea of what that may look like.

So where does the hydrogen come from? Magic? It will not eliminate pollution from personal transport so long as we are dependant on coal or hydrocarbon fired power stations.

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Re: Company wordsmith?

And as for it looks like a "superstar's car" I think I may have a different idea of what that may look like.

I'm not sure there - a lot of superstars would rush out to buy one based on the environmental stuff regardless of what it looks like - look how many Hollywood types were reported as having rushed to buy a Prius when they launched.

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Facepalm

Re: Company wordsmith?

It looks very much like a superstar's car to me.

Unfortunately the one that it brings to mind is Homer Simpson and his self-designed car, The Homer...

D'oh!

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Re: Company wordsmith?

looks like a "superstar's car"

Unfortunately, the superstar in this case is Virgil Tracey.

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Anonymous Coward

frak me

has it got uglier?

Crank up those Nu-clear plants I'm the one with £1000 hole in my bank account where the Tesla model 3 deposit used to be.

Don't get me wrong - I suspect hydrogen is actually a better long term solution - but frak me have they got a long way to go on this evidence. At least the Toyata Mirai looks like an Alpha if you kinda squint.

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Re: frak me

" I suspect hydrogen is actually a better long term solution "

Hydrogen plus nuclear plus a few spare carbon atoms makes for a transportable energy storage system which would work well in vehicles.

If you have the abundant nuclear energy to make hydrogen fuel then you have enough energy to turn it into (at least) propane/butane/octane to make it safer for such operations.

Of course it'd be ironic if future nuke plants were making methane for the gas reticulation system instead of electricity.

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Facepalm

Re: frak me

Exactly. Are they designing a new car or are they designing a new power train?

At least Tesla & Nissan appear to know the answer to this and have kept the car bit of their EVs sensibly standard.

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Stop

Re: frak me @ 2+2=5

No. Add some inflation to your handle.

They've just cadged 2m urox from the EU and an unspecified sum from what I presume are a couple of my money spaffing quangos I've never heard of.

Whalesong, environmentally friendly jostick vape, another round of funding please, look, we've made it super fugly, it MUST be green ...

Trebles all round.

Cynical? Me?

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8.5kW and 0-60 in 10 seconds?

8.5kW is roughly what a 125cc learner motorcycle produces. Those top out at around 60mph. Unless I'm missing something or the article is, something smells here. Even with all that streamlining, acceleration is more about mass than wind resistance, certainly up to around 60mph, and I find it hard to believe this thing is only as heavy as a little Honda.

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Re: 8.5kW and 0-60 in 10 seconds?

I was thinking along the same lines, but the qoted power output is for the fuel cell alone. Presumable the acceleration figures factor in the super capacitors too.

-A.

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Re: 8.5kW and 0-60 in 10 seconds?

You missed the whole section about the fuel cell being for cruising only and the capacitors providing the thump.

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(Written by Reg staff) Gold badge

Re: Re: 8.5kW and 0-60 in 10 seconds?

Indeed - the capacitors are vital in providing the acceleration va-va-voom.

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Joke

Re: 8.5kW and 0-60 in 10 seconds?

They'll probably say it's so light as it gets lift from all the hydrogen...

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Anonymous Coward

Re: 8.5kW and 0-60 in 10 seconds?

Now if it had a flux capacitor I might be interested but then again it's never getting to 88mph even downhill with the wind behind you. Might get there in front of a train if the weight of the train didn't crush it first.

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Re: 8.5kW and 0-60 in 10 seconds?

Torque?

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Re: 8.5kW and 0-60 in 10 seconds?

Acceleration requires capacitor charge generated by braking from a speed achieved by accelerating.

I hope the capacitors don't discharge overnight.

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Boffin

Re: 8.5kW and 0-60 in 10 seconds?

Thanks Cap'n, NOW I understand.

You've got to STOP before you can GO. Simples.

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Mushroom

Re: 8.5kW and 0-60 in 10 seconds?

If the fuel tank ruptures you're almost certain to experience 0-60 faster than the quoted 10 seconds.

See Icon for further details ->

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Re: 8.5kW and 0-60 in 10 seconds?

"

Acceleration requires capacitor charge generated by braking from a speed achieved by accelerating.

"

While the article doesn't say, I would imagine that the system allows for providing charge to the capacitors from the fuel cell if the capacitors are discharged and the car is below a certain speed.

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Re: 8.5kW and 0-60 in 10 seconds?

"Torque?"

Probably quite a lot from the electric driving motors

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Re: 8.5kW and 0-60 in 10 seconds?

"You missed the whole section about the fuel cell being for cruising only and the capacitors providing the thump."

Let's take a punt on the mass being around 300kg with driver. 60mph = about 27M/s, so the ke at that speed is about 150 * 272, 75kJ in round terms. 8.5kW will deliver that in around 10 seconds, though we have to allow for energy loss in the electronics, the motors, and rolling resistance. So I guess everybody else is right and I am wrong, the numbers do just about add up if you add in the supercapacitors. Of course, if the vehicle mass is significantly greater than my assumed 200-220kg, they won't. What started this train of thought was that my old Velo long ago had roughly the same mass as I'm guessing this thing has, and that at something over 20kW it was distinctly underpowered for modern roads.

You can't argue with physics, so I withdraw as gracefully as my perpetual grumpiness can manage.

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Re: 8.5kW and 0-60 in 10 seconds?

From their website: "Our car is very light – the engineering prototype weighs 580 kg."

So your assumed 200-220kg is indeed a bit on the low side, unless the production model will have a significant amount of weight loss.

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Re: 8.5kW and 0-60 in 10 seconds?

> Acceleration requires capacitor charge generated by braking from a speed achieved by accelerating.

So if you pull away from lights at the bottom of a hill, you're buggered?

It would probably have to stop for a (overnight) breather half way up Birdlip hill.

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Re: 8.5kW and 0-60 in 10 seconds?

"the engineering prototype weighs 580 kg"

to put it into context, thats about the same as an original 1958/9 Mini Minor (~12 cwt) - with slide windows, minimal padding on the seats and none of the later safety features added - which pushed the weight up. 850cc engine producing 34 bhp (~25kW) and around 75mph top speed (downhill,,,,,,,with a following wind)

This thing is going to be seriously underpowered.

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Vic
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Re: 8.5kW and 0-60 in 10 seconds?

This thing is going to be seriously underpowered.

Probably.

It does rather depend on the capacity of the supercapacitors; it looks like they're trying to produce something with a low mean power use, but with plenty of zip on tap for acceleration. So on the test-drive, you'll give it a couple of seconds of full-power, and it will seem quite nippy. But you pay for that energy expenditure later...

Vic.

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WTF?

Boy....

..is that ugly.

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Re: Boy....

Yes. If you're not building a Supercar it's probably best not to try to take the styling cues from one. "Noddy's first Ferrari" springs to mind somehow.

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Re: Boy....

Incredibly ugly and impractical, with aerodynamics that only matter past 80mph.

This is like the adams probe 16 (which was a pocket ferrari powered by an anemic austin lump) when a more practical (and saleable) fuelcell vehicle would be more like a Kei van - something with a form factor like the Suzuki Wagon R.

Rationale for that statement: small output, regenerative braking with supercaps (which are very limited in their energy storage), low pollution -> an ideal stop-start city transporter, not an open road cruiser.

A final thought for that design: the hydrogen tank is _very_ exposed to a rear end collision. Not a good thing when it will be operating at ~ 40MPa

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Mushroom

Re: Boy....

the hydrogen tank is _very_ exposed to a rear end collision.

Ah, the Pinto 2.0

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Did they really mean for it to look like that?

I mean TVR used to get the company dog to help out designing cars and theirs were pretty nice.

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Super capacitors are a good touch

Most energy from regenerative breaking lands up getting thrown away otherwise: batteries simply can't take the charge as fast as a vehicle under braking generates it, so horrendous proportions of the energy are lost. A combination of batteries and super capacitors is better yet: the capacitors will be full well before the vehicle finishes breaking; they can offload that slowly to a battery so as to have room for the next time the vehicle breaks (say vehicle goes 60mph -> 40, coast, 40-20, coast, 20->0. obviously if you accelerate hard in between the advantage is negated.) Exactly this fuel cell \ capacitor \ battery malarkey is used in a random research project from Birmingham uni: http://www.birmingham.ac.uk/alumni/news/items/2012/10/Oct-University-builds-the-countrys-first-hydrogen-powered-train.aspx

Don't get me wrong, a car with a top speed of 60 and no luggage space is as much use to me as an umbrella on a submarine, but still I like the idea.

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Re: Super capacitors are a good touch

@theModge

I think you need to understand the difference between breaks and brakes - although transposing the one for the other does lead to some interesting sentences :)

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