Earth Day 2006 has come and gone, but the familiar arguments over energy and where to get it will remain. A couple of days ago, CNN carried an article about President Bush and his love of hydrogen. It's the "fuel of the future" according to the Pres. Friday night, our local PBS station featured a panel discussion about hydrogen, with panelists from various South Carolina universities and businesses. They all spoke in favor of it, without skepticism. These were highly educated professional men and women, not politicians or businessmen with obvious conflicts of interest (though I suppose that the prospect of research grants may be enticing for the university folk). Senator Lindsay Graham made a pre-recorded appearance in which he gushed over the virtues of hydrogen and announced his intention for South Carolina to become "the Detroit of Hydrogen". (Which may be prophetic, depending on which characteristic Detroit you're talking about.)
Hydrogen is the kind of thing that sounds great at first, but becomes progressively worse the more you learn about it. It is in fact a terrible idea, completely unsound both economically and environmentally. And yet we find ourselves with the government, industry, and many (most?) environmentalists calling for the coming "hydrogen economy" with complete enthusiasm, in many cases at the expense of backing more effective policies. Let me explain why this is insane.
First of all, to state what should be obvious but for most people apparently isn't, hydrogen is not a source of energy. It is at best merely a delivery mechanism for energy produced by other means. You don't find molecular hydrogen sitting around on Earth in any significant quantity, so you have to make it. And thanks to a little thing called the second law of thermodynamics, any method you use to produce hydrogen will always require more energy than you can get out of it. Hydrogen is therefore fundamentally incapable of meeting our energy demands or reducing our addiction to fossil fuels.
Speaking of fossil fuels, for the foreseeable future, that's where most of the hydrogen would be coming from. There are basically two methods of making hydrogen. The first is to reform fossil fuels, the idea being that, rather than burning hydrocarbons directly, you extract the hydrogen out and dump the resulting CO2 (which incidentally will go where all of our carbon currently goes -- into the atmosphere. Global warming is yet another problem that hydrogen promises to exacerbate rather than solve.) The problem with this is that you lose a large chunk of the energy. Using methane (CH4), aka natural gas, you lose about 30% of the energy by converting it to hydrogen. Since methane is the most hydrogen-rich fuel, the losses would be far greater if you were to use oil or coal. What exactly is to be gained by this? Natural gas can be burned to make electricity with efficiencies approaching that of hydrogen fuel cells. Converting it to hydrogen first would result in a net loss of energy. Even better, the gas can be burned directly for cooking or heating, which makes a lot more sense than converting it first into electricity.
The other method of making hydrogen is electrolysis. You stick two electrodes in water, run an electric current between them, and the water will be "cracked" into molecular hydrogen and oxygen. Obviously, you can't do this without a source of electricity. So you are basically using electricity to make hydrogen, which will then be used to make electricity. In the process, you lose somewhere between 40% and 60% of the energy, depending on your set-up. Why even bother? Just use the electricity directly and cut out the middle-man. Hydrogen does have an advantage in that it can be used as a method of storing electricity. But there are already lots of storage options (e.g. batteries, flywheels, pumping water uphill) that are far more efficient and less expensive.
And where does the electricity to make hydrogen come from? For the time being it would come mainly from coal, because that's where most of our electricity already comes from. Sadly enough, unless we get serious about alternatives, coal will be our main electricity source for the foreseeable the future. If we were to effectively switch our entire transportation sector over to coal, with at least half of the energy being wasted, it would be an environmental nightmare. That's why hydrogen advocates talk about making hydrogen using nuclear or renewables such as wind and solar. But nuclear is stalled thanks largely to environmentalist objections, and renewables are currently not cost-effective enough to capture any significant market share. Any talk of making hydrogen from these sources is foolish until such a time when they can stand on their own. And last I checked, while President Bush is pushing hydrogen, he is not pushing renewables. Even assuming that renewables come down drastically in price or that the nuclear industry experiences a rebirth (both of which I would like to see), hydrogen is not what that electricity should be used for. From an environmental standpoint, we are better off phasing out coal and letting our cars continue to burn gasoline. Only when we have a surplus of clean energy (in which case most of our air pollution and global warming problems will have been solved), then it might make sense to consider turning the surplus into hydrogen. But if and when we ever get to that point, the smartest thing to do would be to switch our auto fleet over to battery power, not hydrogen.
So the biggest problem with hydrogen is, you know, where to actually get it. It's really hard to believe that this supposed "fuel of the future" doesn't actually exist and can't be made without putting more energy into it than you get out of it. If that were the only problem with hydrogen, it would be enough to dismiss the whole thing as little more than an interesting but not particularly effective means of moving energy around. Unfortunately, things get worse.
Hydrogen has a lot of energy per unit mass, but it has very little energy per unit volume. When you hear PhDs talk about the "storage problem" on a PBS show, you get the impression that this is a little technical glitch that we'll soon work out. The reality is, the storage problem is intractable, and renders hydrogen completely useless for cars until someone invents a magical new technology that does everything short of violating the laws of physics.
As things stand today, there are two options for storing hydrogen onboard a vehicle. The first is to liquefy it and put it in a cryogenic tank. This means cooling the hydrogen down to just over absolute zero. Having something that cold on board presents all manner of technical problems. You have to have specially designed seals and pipes to keep them from cracking. And since there's no such thing as a perfect insulator, a certain percentage of the hydrogen will boil off each day, leaving you with an empty tank (and wasting precious, precious energy) if you leave your car parked for too long. Refueling presents a problem as well. I once saw a pitch for hydrogen that actually bragged about the fact that in a hydrogen economy, robots will refuel your car. To reverse a popular saying, this is not a feature, it's a bug. You don't want untrained humans getting anywhere near liquid hydrogen in case they splash a little on themselves and cause permanent tissue damage. And even after liquefying the hydrogen, it still takes up 4 times as much space as a gas tank with comparable amount of energy. But by far the worst problem with liquid hydrogen is that you waste about half of the energy during the cooling process. Whatever you had to pay for the hydrogen, whatever environmental damage was caused by its production, take that and double it. That's what you get from using liquid hydrogen.
The other method of storing hydrogen is simply to compress it as a gas. If you compress it down to about 10,000 psi, you "only" need a tank about 10 times the size of an average gas tank to get you as far. During compression, you also waste about 15% of the energy. And whatever you do, try to stay out of accidents. You really don't want a 10,000 psi tank filled with a highly combustible gas to rupture. Imagine the Hindenburg disaster concentrated into something the size of a gas tank sitting right under you.
So the storage issue really, really sucks. Because our current means of storage simply won't work, there are other, more exotic means of storing hydrogen that are on the drawing board. These include storage in the form of metal hydrides, or super absorbent materials that could hold lots of hydrogen. I won't go into detail about them, but suffice it to say that none of these purported solutions are currently feasible. And they may never be.
The storage problem unfortunately impacts every part of the so-called hydrogen economy. Being the smallest molecule in the universe means that hydrogen leaks out of anything you try to stick it in. The metal within pipelines is made brittle by the formation of metal hydrides, so you need super thick pipes that add considerably to cost and weight. This is why almost all hydrogen used for industrial purposes is produced on-site. Moving it around or trying to store it for any length of time is a major problem. And please note, the fact that hydrogen can store electricity is really the only thing it has going for it. When a technology's biggest advantage is really a disadvantage, that's not a good sign.
I'm going to leave things there for now. I could mention lots of other problems, each one damning in its own right. For example, there is the fact that PEM fuel cells are hideously expensive and don't last long. Then there is the fact that we have no infrastructure for distributing hydrogen and would need to invest hundreds of billions of dollars just get us to where we are now with gasoline. And it just keeps going. There are so many problems with hydrogen that it's hard just to remember them all. What I find both baffling and seriously disturbing is that there are a lot of people, many of them very intelligent (like our dear, sweet President), who are trying to push the hydrogen economy forward, and planning on spending a lot of tax dollars to do it. It deserves instead to be tossed on the scrap-heap of failed ideas. I hope we don't get in too deep before it becomes obvious to everyone else.
