a column praising California Governor Arnold Schwarzenegger for filling
up a hydrogen-powered Hummer (figure 20.25). Nature’s article lauded
Arnold’s vision of hydrogen-powered cars replacing “polluting models”
with the quote “the governor is a real-life climate action hero.” But the
critical question that needs to be asked when such hydrogen heroism is
on display is “where is the energy to come from to make the hydrogen?”
Moreover, converting energy to and from hydrogen can only be done inef-
ficiently – at least, with today’s technology.

Here are some numbers.

If our task were “please stop using fossil fuels for transport, allowing your-
self the assumption that infinite quantities of green electricity are available
for free,” then of course an energy-profligate transport solution like hy-
drogen might be a contender (though hydrogen faces other problems).
But green electricity is not free. Indeed, getting green electricity on the scale
of our current consumption is going to be very challenging. The fossil
fuel challenge is an energy challenge. The climate-change problem is an
energy problem. We need to focus on solutions that use less energy, not
“solutions” that use more! I know of no form of land transport whose energy
consumption is worse than this hydrogen car
. (The only transport methods I
know that are worse are jet-skis – using about 500 kWh per 100 km – and
the Earthrace biodiesel-powered speed-boat, absurdly called an eco-boat,
which uses 800 kWh per 100 p-km.)

Hydrogen advocates may say “the BMW Hydrogen 7 is just an early
prototype, and it’s a luxury car with lots of muscle – the technology is
going to get more efficient.” Well, I hope so, because it has a lot of catching
up to do. The Tesla Roadster (figure 20.22) is an early prototype too, and
it’s also a luxury car with lots of muscle. And it’s more than ten times
more energy-efficient than the Hydrogen 7! Feel free to put your money
on the hydrogen horse if you want, and if it wins in the end, fine. But it
seems daft to back the horse that’s so far behind in the race. Just look at
figure 20.23 – if I hadn’t squished the top of the vertical axis, the hydrogen
car would not have fitted on the page!

Yes, the Honda fuel-cell car, the FCX Clarity, does better – it rolls
in at 69 kWh per 100 km – but my prediction is that after all the “zero-
emissions” trumpeting is over, we’ll find that hydrogen cars use just as
much energy as the average fossil car of today.

Figure 20.26. BMW Hydrogen 7. Energy consumption: 254 kWh per 100 km. Photo from BMW.
Figure 20.27. The Earthrace “eco-boat.” Photo by David Castor.
Figure 20.28. The Honda FCX Clarity hydrogen-powered fuel-cell sedan, with a Jamie Lee Curtis for scale. Photo courtesy of automobiles.honda.com.