My last post with this title dealt with the impossibility of fueling China on petroleum. If China's population problem is the Iron Denominator, than I suppose globally we could speak of the Steel Denominator - or Tungsten, Titanium, or Molybdenum. Fueling one billion people will seem relatively easy compared to the problem of feeding, clothing, and educating all of the Earth's predicted 9 billion by 2050. Also, even today China may be the biggest single country, but there's still five billion more of us here outside of the Middle Kingdom. At the end of that post, I said that the world needed to find other options, and fast.
On that note, the Popular Science this month has a piece titled "Hydrogen Fuel Cell Myths", in which it purports to debunk many of the claims made about the future of a Hydrogen Economy. Now, I've gone from being a fuel-cell evangelical to being a fuel cell skeptic several times in the last few years, but the more I read (and I don't pretend to have any expertise more than any other layman) the less optimistic I am about fuel cells in general, and hydrogen in particular.
Most of the problems associated with hydrogen as a fuel source are well known. Hard to make, harder to store, and posessing of an unfairly negative reputation when it comes to explosions, hydrogen's main attraction seems to come from the fact that most people are under the impression that we can switch over to hydrogen and presto! Problem solved! Cars are nothing but good, for ever and ever! Of course, this isn't the case. In the case of the United States, making hydrogen renewably from water would require adding dozens, if not hundreds of large-scale power plants (or their equivalent in solar or wind) and would require increasing the United States' water use by 10%, or 4 trillion gallons a year.
Now, biofuels look better when it comes to storage and useability. Ethanol and Methanol both have been touted as possible alternatives to a pure-hydrogen economy. The problem here is that even covering the entire continental US in fuel crops still isn't enough. Or rather, it would be in short order because most drivers would starve, presumably taking their cars off the road.
Then there's a more basic problem. Even if we can make the hydrogen cheaply and widely availble, there's still the question of efficiency. Assuming you start with water and electricity to make the hydrogen, there is no way you can physically recover as much energy as you put in to making the hydrogen with fuel cells. It makes almost no sense to generate electricity for hydrogen production, simply to reconvert the hydrogen to electricity. This is physics, not economics or engineering.
An thus far, our engineering is way behind the physics. It is still, from the point of view of mileage, better to drive a battery-powered car than a hydrogen car. In a recent competition, battery-electric cars ran a race through Los Angeles, doing 100 miles of track. As a showpiece, a hydrogen powered car was included in the race - it had to be refueled twice, and lost the race by a wide margin.
So simply switching technologies is not going to be enough. We are going to have to become radically more efficient (something Bucky Fuller, patron saint of this blog, advocated in the 1960s - way before it was cool) and change our lifestyles, too. I can't imagine anyone owning an SUV in 20 years. At least, not if they're sane.
One of the biggest advocates of fuel-cell cars has been Amory Lovins of the Rocky Mountain Institute. The RMI has a great book out, Natural Capitalism. (You can download the book here.) I would definitely reccomend it to anyone really interested in this stuff, but I think a lot of hydrogen evangelists suffer from serious optmism-overloads. I've read a lot of arguments that, with new lithium-ion batteries, electric cars may soon have ranges of 1000+ miles on a single charge. Of course, even without lithium-ion batteries, current cars can go 200 miles. Considering your average gas-guzzling American commutes less than 50 miles every day, there's already a serious possibility here.
All battery talk aside, the world is still going to need renewable hydrogen in the future - chemical fertilizers are currently made by combining fossil-fuel hydrogen with atmospheric nitrogen to make ammonia, and with that nitrate fertilizers. When oil and natural gas run out, either we go all-organic or we find new hydrogen for fertilizer. It might be preferable to go organic, but this might not be an option when the world's population is stretching 10 billion. So again, the world will need new options.