Step away from the hydrogen

There's one thing about Top Gear that irritates me. No, not that - I actually enjoy all those things that usually irritate people about Top Gear. Even Jeremy Clarkson. What gets on my nerves is something that the show shares with Arnold Schwarzenegger when he was Governor of California. They think that using hydrogen to power cars is a good thing.

I have always found this extremely dubious - and I am glad to say my view is backed up by the interesting and authoritative book I've just reviewed, Project Sunshine.

On a shallow level (come on - Top Gear, Arnie??) hydrogen fuelled cars make sense. Hydrogen is an effective fuel and when it burns all you get is water. No nasty carbon dioxide. But hydrogen is also a real nightmare to handle.

Firstly, as a gas it takes up a lot more room than petrol. Around six times as much at a practical compression. So for any particular tank size, you will have 1/6th the range. It is also wildly inflammable, would need to be stored at high compression (so thick, heavy walls required for the tank, industrial scale connectors)... and despite being obtainable from water, it is quite expensive to make and transport - everything about it screams 'avoid me like the plague'.

Bizarrely, Project Sunshine suggests a much more likely fuel than hydrogen (or batteries) is methanol. The stuff they run some racing cars on - you would have thought a much more natural affiliation for the Top Gear petrol heads. Although this does give off carbon dioxide it is cleaner than petrol and can be made from the carbon in the air, making it carbon neutral. The interesting point the book makes is that storing energy in chemical bonds - in a fuel like methanol - is likely to always be significantly more efficient than batteries. So strangely even the electric car may turn out to be a relatively short term blip in the future of driving. Bring on the methanol.

This has been a green heretic production