Saturday, December 20, 2008

The FCX Clarity from Honda

Honda FCX Clarity

On this week's Top Gear, James May called the FCX Clarity "the most important car for 100 years".
[Photo courtesy of] It runs on hydrogen, which "will never run out", because it is "the most abundant element in the universe". And the only emissions are water.
What twaddle!
The programme took the time to point out that the electricity to power a Tesla electric car in Britain is produced at a fossil fuel power station. Why didn't they also discuss where the hydrogen comes from?
Top Gear loves to quantify accelerations, lap times, car prices, top speeds - why couldn't they quantify the energy requirements to run "the car of the future", the FCX Clarity? And compare it with the Tesla?
Here's the answers, according to chapter 20 of Sustainable Energy - without the hot air.
Energy consumption (in kWh per 100 person-km) versus typical speed
The energy consumption of the FCX Clarity is 69 kWh per 100 km. (Very similar to the consumption of an ordinary fossil fuel car.) That's assuming the hydrogen is produced in the standard way, using lots of methane and a bit of electricity, and counting one unit of chemical energy as having the same energy content as one unit of electricity. Meanwhile, the energy consumption of the Tesla (according to its manufacturers) is 15 kWh per 100 km. (Of electrical energy.) Even if we penalize electricity, saying "every 1 kWh of electricity costs 2.5 kWh of fossil fuels", the Tesla is still much better than the fuel-cell car, and better than the average fossil fuel car. (And in the future, we won't be getting electricity from fossil fuels, hopefully!)
So the hydrogen car is NOT a "solution" to our problem, if our fundamental problem is an energy problem.


Unknown said...

You should maybe write to the BBC Trust and point out that 'balance' would be a fine thing on a program that doesn't advertise itself as satire or lobbying...



Unknown said...

Whilst it was not fair and balanced of the BBC to point out the environmental drawbacks of using the national grid for power supply to the Tesla but not for the Honda FCX Clarity, James May DID point out that the major environmental issue with using Hydrogen cars was indeed the production of Hydrogen.

This particular episode wasn't focussed on being "environmental" as much as contrasting the two alternative non-fossil fuel technologies for the future powering of cars. Given that hydrogen cars can be feasibly filled up in 2-3 minutes this makes the technology, in principal, the way forward.

What we need to do now is to invest in the research and development of reliable, clean and efficient hydrogen production. We already have reliable and efficient energy "production" through careful use of Nuclear power plants... As Top Gear presented, we already drill for oil beneath the oceans - a vast technological achievement in its own right.. perhaps Hydrogen fuel cells really are the way forward for portable, clean energy.

David MacKay FRS said...

Yes, James May did say (after praising Hydrogen 5000 times) that the only small problem is the production of the hydrogen. But making an analogy with "getting oil out of the ground" is really stupid. When you get oil out of the ground (difficult achievement, yes), the energy in the oil more than covers the cost of getting the oil out. This will never be the case for hydrogen. Making hydrogen requires energy (and more than you ever get back from using the hydrogen). So it's not a small problem. It is THE problem.

Unknown said...

Dear Mike,

I think it can be established that hydrogen is a very bad idea from an energy efficiency point of view. If you need more convincing (other than David MacKay's book), try to get hold of a paper called "Does a Hydrogen Economy Make Sense" by Bossel, IEEE Proceedings Vol 94 Num 10 pp. 1826 onwards, 2006.

To quote from this paper: "Fundamental laws of physics expose the weakness of a hydrogen economy. Hydrogen, the artificial energy carrier, can never compete with its own energy source, electricity, in a sustainable future. The discussion about a hydrogen economy is adding irritation to the energy debate. We need to focus our attention
on sustainable energy solutions. It seems that the establishment of an efficient electron economy should become the common goal."

And by the way, the author is an expert on fuel cells.

Your sole argument (and Top Gear's) for hydrogen against EVs is that you can fill a hydrogen vehicle quickly. This is a good point, but it is not an insurmountable obstacle for electric vehicles: (1) 'filling stations' with higher power connections (eg 3 phase) could be established (2) battery swap facilities could be established and so on. Sorting this out will be so much less challenging than drilling for oil!

Hydrogen may have a small place as a range extender for long journeys but otherwise I think the physics does not add up and it is a shame that James May, who normally thinks through things a bit more, did not realise this.

Dave Howey

Joe said...

Hi - I wonder if you have any comments about the discussion stemming from the Guardian about the emissions from fast trains (and sleeper trains) compared to air transport. They apparently think the former can be as bad as the latter.

Beast Of Bodmin said...

"Given that hydrogen cars can be feasibly filled up in 2-3 minutes this makes the technology, in principal, the way forward."

Just because of the fill-up time? What about the not-very-attractive EROI for hydrogen?

In any case, A123 systems will sell you a LiFePO4 battery that can also recharge inminutes. These batteries have other advantages over other battery types.

Neil said...

You mean the UK doesn't have Wind generators or Nuclear power?
You are kidding me! :)

Unknown said...


Michael said...

The approach those three have to electric cars is similar to The Simpsons' view that nuclear power makes three-eyed fish and trees which glow in the dark.

Hydrogen would be ideal as an energy storage system from renewable energy when operating and nuclear at non peak times, like pumped storage, but I don't see the need to develop it for transport.

I especially don't see the need for Top Gear to extol the virtues of hydrogen whilst ridiculing electric cars! There is no hydrogen economy! There's no hydrogen infrastructure, whereas there is an electric infrastructure: the grid.

That said, if we figure out fusion and energy stops being a problem, then maybe hydrogen would make sense! I hear fifty years is a safe bet...

Anyway, I absolutely loved the book! I'm going to promote it to the fullest extent on my website. Perhaps this is my shiny new physics degree talking, but I found it the most useful book on the subject I've read yet.

And not once did you tell me to stop using plastic bags...