We don’t hear it as much now in the media, but we still hear it informally. When we bring up the Triple Threat with people, they ask, won’t the hydrogen economy help us move to a sustainable future? Let’s look at why it’s so exciting to talk about hydrogen, how a hydrogen economy would work, and why hydrogen is unlikely to be a genuine solution.
What Makes Hydrogen Such Fun To Talk About
Hydrogen is abundant throughout the world. By one measure, it accounts for about 90% of the atoms in the universe.
Fuel cells can convert hydrogen to electricity to power vehicles in a quiet, clean, relatively safe process from which the only by-product is water. And making hydrogen is actually a simple process. You can even do it at home. Viewed optimistically, the prospect of the hydrogen economy is one of virtually unlimited energy, low in weight, with no greenhouse gases, no fossil fuel consumption, and no dependence on foreign countries. It’s the energy trifecta.
Advocates envision a complete energy makeover, in which hydrogen, the “forever fuel,” cheap, clean, and easily transported and stored, would become so simple, so ubiquitous, and so sensible, that it would become the energy coinage for all of society, powering not only its vehicles but also its factories, its schools, its churches, mosques and synagogues, even its airplanes and spacecraft. And doing so at a price so low it wipes out poverty. This is heady stuff.
The U.S. President and the Congress became convinced in 2003-04 that hydrogen would be the answer to our energy needs and committed billions of dollars to research on the hydrogen economy. As you’ll read below, this probably reflects a society that pays more attention to economists and politicians than to the voice of science.
How the Hydrogen Economy Would Work
The hydrogen economy is mainly about transportation and agricultural traction (tractors and combines). For other purposes, for example industrial plants, residential power, and commercial power, simple electricity works better. The reason hydrogen is so interesting for transportation is that it can be transported from where we make it to where we need to produce power with it.
The hydrogen economy would consist of a new fleet of vehicles equipped to carry on board a significant quantity of hydrogen. These vehicles would be equipped with fuel cells that would convert the hydrogen to electricity as and when needed to drive an electric motor for the vehicle, as well as to power accessories like radios, lights, etc.
Part and parcel of the hydrogen economy is an infrastructure to support it. This would include hydrogen filling stations at dependable intervals on roadways and multiple generation plants to produce the hydrogen and deliver it to the filling stations.
Why It’s Unlikely To Work
With all the promise of a hydrogen economy, you’d think we would be advocating a full-scale conversion effort. We would, if it weren’t for several pesky problems and one deal-killer. Let’s take them in order. First the pesky problems.
You Still Need Energy
Understand that hydrogen is not an energy source. it’s an energy storage technique. Hydrogen does not occur naturally in the atmosphere, so the only way to get hydrogen is to invest energy to isolate it. To be tacky, to wax rhapsodic about hydrogen is logically equivalent to getting misty-eyed and saying “gas tanks!”
Hydrogen is Hard To Store
Hydrogen is not at all dense. Just for grins, know that if you carried enough hydrogen at normal pressure to drive an automobile 300 miles, it would take a tank about the size of seven cars to hold it.
Pure hydrogen in gas form is highly corrosive and will not stay in a sealed container. It’s too slippery. Individual hydrogen atoms are so small they will pass through steel and sometimes remain inside it. When one hydrogen atom meets another and bonds to it, they become a larger molecule that gets stuck inside the metal, forming a blister that can split the metal. Sometimes the hydrogen atom bonds with carbon and forms methane and breaks down the strength of the steel. This process is called “hydrogen embrittlement” or “hydrogen attack.” Makes you nostalgic for good old gasoline, doesn’t it?
The usual approach to hydrogen storage is to place it under high pressure, which requires large amounts of energy just for the storage. A great deal of the expensive research the U.S. government is financing into the hydrogen economy is focused on the difficulties of hydrogen storage and handling, and various ideas for making them manageable. Among the ideas that seem to have the most promise are to store hydrogen in hydride form, in an ethylene covering, as an ammonia tablet, or in an organic polymer. No one has developed a storage mechanism for hydrogen, however, that does not involve prodigious expense, high levels of energy invested, or both.
For safety reasons, some of the hydrogen in a tank must be allowed to evaporate slowly. This means that, over a period of two weeks, a stationary tank of hydrogen would need to be depleted by half, even if the vehicle isn’t driven at all.
Hydrogen becomes more stable as a liquid, but that requires lowering the temperature to minus 423 degrees Fahrenheit (again, more energy). And at this temperature, the substance is so dangerous no human can get anywhere close to it. It must be thoroughly insulated and handled remotely.
Hydrogen is Explosive
We all know that gasoline is flammable, but it’s actually pretty stable compared to hydrogen. Hydrogen in the tank of a fuel cell vehicle is usually under intense pressure, so it’s vulnerable to a rupture in a high-speed accident. The rapid combination of large quantities of hydrogen with oxygen from the air in the presence of any heat source like a spark or a glowing cigarette could create a truly scary conflagration. Think the Hindenburg. Or think the Challenger space shuttle in 1986, when hydrogen slipped through a seal on the fuel tank into the flame from the jet, igniting the spacecraft in a disastrous explosion that those of our age will remember as long as we live. We’re not yet aware of a high-speed accident involving a hydrogen-powered land vehicle, but know that it won’t take many such accidents before the culture knows all about the hazard.
Hydrogen is Low in Weight but High in Volume
Even under pressure, hydrogen takes up a great deal of space for the energy it contains when compared to gasoline. As we design hydrogen vehicles, we would need to devote more space to storage tanks or settle for shorter cruising ranges. Research is underway to encapsulate tiny quantities of hydrogen in crystals that would hold the chemical until it’s needed. They enable higher densities of energy storage, but they also require significant additional energy.
Another challenge from hydrogen’s low density is one of infrastructure, getting usable hydrogen distributed to that network of filling stations in a safe, reliable manner. Present technology is to store it in massive tanks in liquid form at the station (remember, minus 423 degrees Fahrenheit – more energy). Notice how we conveniently skipped right over the task of getting the liquid hydrogen to the station in the first place. Soon before the customer calls for it (call ahead to place your order for 250 miles’ worth), the station pumps the liquid hydrogen into equally massive warming towers where the liquid hydrogen is allowed to boil and form a gas (this one will soak up heat – can we at least tap the cold air for the station’s drink machines?). Then, the gas is pressurized to 5,000 psi and pumped into individual storage tanks that, typically, would be loaded onto the vehicle (more energy, but this time presumably human). And these are no featherweights. The hydrogen may be too light, but the metal (or more likely, polymer) tank to contain it isn’t. Scientists’ best guess is that a hydrogen vehicle with no fuel will weigh almost as much as one that’s fully-loaded with fuel.
Fuel Cells Are Expensive
Getting hydrogen to the vehicle doesn’t make the wheels go round and round. To do that, you need to convert the hydrogen to electricity in some kind of controlled way, using a fuel cell. A fuel cell combines hydrogen and oxygen to form water, and the process gives off electricity that the vehicle can use to power the electric motor used to drive the vehicle.
The industry is reluctant to talk about the cost of fuel cells. The only available data puts the cost of a production fuel cell, with the full benefit of economies of scale, at about $70/kw, or about $5,000 for enough to generate 100 horsepower. And that’s only to produce the electricity; you still need to pay for the electric motor to do the actual driving. The fuel cells promise to have a relatively long life, but only if they are never exposed to impurities in the hydrogen used to power them. Any impurity (virtually a certainty now in the gasoline supply) would shorten the life of the fuel cell dramatically.
And Now the Deal Killer
Basically, the physics don’t work. No matter how you slice it, except for rare circumstances like space travel, it just doesn’t make sense to invest the energy needed to take perfectly useful electricity, use it to isolate hydrogen, pressurize or liquefy the hydrogen, transport and store the hydrogen, use the hydrogen to power a fuel cell, and then use the resulting electricity to propel a vehicle. It’s always simpler to just store the electricity in a battery and use it. If you don’t believe us, believe the guy who understands energy economics, Ulf Bossel. You can read his paper entitled Does a Hydrogen Economy Make Sense? and decide for yourself.
Here’s a great graphic showing why the “hydrogen economy” just doesn’t seem to stack up to the “electron economy.” What it tells us is that by the time you use electricity to isolate and compress hydrogen and then use a fuel cell to convert the hydrogen back to electricity to drive an automobile, you’ve lost all but 25% of the energy with which you started. An electric car, on the other hand, involves fewer energy migrations and can deliver “grid-to-motor efficiency” of more than 80%.
And this essential principle holds regardless of what energy source you use to separate the hydrogen, whether you use natural gas, or biomass, solar, wind, or hydro. it doesn’t matter. It will always make more sense to use electricity to charge a battery to power an electric vehicle than it will to divert the energy to the isolation of hydrogen and the operation of an inefficient fuel cell.
And if it’s crucial to you to spend the money to have a new infrastructure like the one that would be needed to power the hydrogen economy, use it instead to distribute replacement batteries that travelers can swap out on the road, or better still, develop ways they can leave the battery in place and just refresh the electrolyte in it.
At some point, the culture will figure this out and give up on the “hydrogen economy,” but not before we waste billions more on research trying to make this doomed technology do what we can already do now with electricity. And if we put 1/10 of the money we’re investing in hydrogen research into making a better battery, we might someday be glad we ran out of cheap petroleum.
And while we’re on the subject of what we should be doing instead, let us get in a plug for the ideal post-petroleum vehicle. Somebody smart is going to wake up soon and realize that this is where the money is in the years ahead.