Story by Charlie Singleton
We’d like to extend a warm welcome to “Charlie Singleton”, a scientist and auto enthusiast who will be sharing his unique perspective with our readers on a semi-frequent basis. No, that’s not his real name — jb
The hydrogen car, once a promising alternative fuel technology, died after a long, courageous struggle against logic and evidence in Washington DC on May 7, aged 43. It is survived by two brothers, the plug-in hybrid and the gasoline-electric hybrid, and by its father, the electric car.
Its death was announced by Dr. Stephen Chu, Secretary of Energy, in a dispassionate statement delivered after ceasing heroic life support measures. “We asked ourselves, ‘is it likely in the next 10 or 15, 20 years that we will convert to a hydrogen car economy?’ The answer, we felt, was ‘no.’”
So it goes.
The hydrogen fuel cell has seemed like a good idea ever since the GM Electrovan, the first fuel cell car prototype, in 1966. It burns hydrogen, the most plentiful element on earth (ooo!), the exhaust is pure water (wowie!), and it drives just like a regular car (gee!). Just the words “fuel cell” bring heady visions of a Jetsons future – like the jet pack, the hovercar, and the household robot to help Mother with the chores, it hearkens to the cleaner, cooler retrofuture we all dreamed of as kids after flipping through Popular Mechanics.
Dr. Chu pulled the plug on a patient that many of you, I’m sure, are surprised to hear was doing so poorly. After all, it was just last year that the Honda FCX Clarity was delivered to customers – the first hydrogen fuel cell car available for lease. Aside from the ’66 Electrovan, we’ve been bombarded with all sorts of fictional and real fuel cell vehicles – GM being a particularly strong proponent with its fuel cell concept cars such as the Sequel and HYmotion, and a few prototypes like the Equinox Fuel Cell. Ford, Toyota, and a raft of other makers signaled their interest in fuel cell technology with concept cars and converted production models. So why’d it kick the bucket, healthy as it looked?
The first, and least compelling reason, is that the car that’s wrapped around the fuel cell is a tenth the price of the fuel cell itself. If Honda sold the FCX Clarity, they’d have to ask for $600,000 just to clear costs. Inside that fuel cell are many layers of precision-engineered membranes and expensive platinum and rhodium catalysts (which speed up the reaction between hydrogen and oxygen, the energy released from which goes to generate electricity). A fuel cell capable of powering a 130hp traction motor is about as expensive as 12 pounds of good cocaine and hookers to do it with – especially at the low volumes automotive fuel cells are made at these days.
The second is the oft-beaten drum that hydrogen requires an expensive new storage and delivery infrastructure. Hydrogen is tricky because it’s a small, slippery, and very reactive molecule – it easily escapes through a microscopic crack in a tank or pipeline, it makes containers brittle, and it has to be chilled to negative 425°F to remain an energy-dense and transportable liquid. Construction of a nationwide system of hydrogen filling stations with on-site hydrogen generation from natural gas or water, would a cost 3-4 billion dollars, according to the Rocky Mountain Institute, an energy think tank.
Those are technical issues, however, and therefore surmountable. Research is ongoing on catalysts that are made from cheaper stuff like cobalt, for example. Fuel cells are really not terribly bad ideas considered alone – the energy output per cell volume for fuel cells has improved markedly, and their size and complexity has gone down. And they make very good use of the hydrogen they’re fed; much more energy makes it from the fuel cell to the road than is the case with the internal combustion engine.
Unfortunately, it’s getting the hydrogen to the fuel cell that presents the real problem. Fuel cell cars are quite efficient at turning energy in the tank into energy on the road – a metric called Tank-to-Wheel efficiency, not dissimilar in principle to miles per gallon. Getting that energy to the tank is a different story – a story told by ‘Well-to-Tank’ efficiency. Those two figures combined yield ‘Well-to-Wheel’ efficiency: the energy expended in the entire process of obtaining the energy, transporting it to the car in a usable medium, storing it, burning it, turning the wheels, and moving the car.
The wonks and geeks at Argonne National Laboratories published a report in 2001 that modeled well-to-tank energy expenditure for a variety of alternative fuels and drivetrains. Their estimates assumed that the vehicle’s characteristics aside from drivetrain were identical – that the only variable was the drivetrain and the fuel it used. They considered a wide range of conventional fuels for either regular cars or hybrids, as well as a variety of alternative fuels, methanol fuel cells, and fuel cells running on hydrogen derived from water and from natural gas. Their results are freely available here. I’ll hit on the big, take-home messages.
Argonne’s results were surprising – and damning. Normal gasoline vehicles use about 7000 BTU (a unit of energy) per mile from well to wheel . Diesels, owing to their more efficient burn of their energy-dense fuel, did better – around 6000 BTU/mile. Domestic natural gas came in slightly lower than gasoline. Hybrids burning gasoline did as well as diesel at 6000 BTU/mile, and diesel hybrids scored ~4800 BTU/mile. Fuel cells oxidizing hydrogen and methanol derived from natural gas were next up – a bit more efficient than hybrids at 5-6000 BTU/mile.
Hydrogen made by running electricity through water – a process called electrolysis, and touted as the ‘greenest’ way to make hydrogen to run through a fuel cell? That’ll run 10-12,000 BTU/mile.. Expressed more clearly, that means that hydrogen wastes roughly 85% of the energy you started off with before it ever reaches the fuel cell. Why? Electrolysis is only 50-70% efficient – you waste half to 1/3 the quantity of chemical energy you get out as usable hydrogen just making that very hydrogen. Then you’ve got to chill and compress it until it’s a liquid. Then you’ve got to keep it a liquid, in a very large tank, in your car. Then you use it.
Argonne didn’t study electric cars in relation to the other alternative fuels, but some Norwegians did. Now, please excuse the unit change, as their results were expressed as percentages of the total energy you mined or generated that actually went to move the car. Regular gassers? 10% efficient. Gasoline hybrids, 27% efficient. Fuel cell cars? 10-28% efficient. Electric cars? 28-80% efficient. My back of the envelope calculation suggests that means an electric car uses as little as 2000-2500 BTU/mile.
Greenhouse emissions are an issue too – politically and environmentally. There’s a big issue with carbon emissions from a traditional car which is why you have to tax your car according to it’s emissions. This means that there would be an advantage for hydrogen cars because surely a vehicle emitting nothing but steam can’t be bad for your carbon footprint, right? Except all that wasted energy – which, of course, has to come from a power plant – represents greenhouse emissions itself, from the coal or natural gas that was burned to generate it. So the greenhouse emissions of a fuel cell vehicle are almost identical to that of a Prius.
But what about renewable energy? Couldn’t that be used to create hydrogen? Sure. But it’s expensive. Few renewable sources are as cheap as coal and oil. Even nuclear, which is greenhouse emissions free, is energetically and financially staggering. You could create hydrogen renewably, at a tremendous cost – and renewable energy to fuel one hydrogen car could just as easily go to charge three vastly more efficient electric cars or plug-in hybrids.
Hydrogen cars use a fuel that, if it’s produced cleanly, from water, wastes nearly the energy required to run a Prius – energy that is either derived from fossil fuels or is prohibitively expensive. If it uses fuel that is dirty, cheap and accessible, it’s no more efficient than that Prius, but its platinum-loaded fuel cell would make it unavoidably more expensive. In every respect, a hybrid, a diesel, or any reasonably efficient standard car is cheaper to buy, fuel, and run – even now, when global warming and expensive fuel from places that hate us are facts of life. Which makes a balance of hybrids, natural gas, biofuels, electric cars, increased fleet efficiency, and mass transit a more sensible policy for the DOE to pursue.
From the standpoint of pure energy efficiency, electric cars are superior to hydrogen. If you stir in value and costs to the consumer, diesels and hybrids join in for the curb-stomping. No matter how you slice it, the hydrogen fuel cell offers no advantage over less costly, less complicated technologies that require less development and investment.
Which brings us to what killed the hydrogen car. It killed itself, because it ran on hopes, PR , gullibility, and flawed assumptions just as surely as it ran on hydrogen. Hydrogen has always been an economically and environmentally unsound fuel. But now that push is coming to shove, as we begin seriously looking for ways to manage our use of expensive energy while avoiding geopolitical and environmental traps, the luxury of throwing good money at bad ideas in the hope that they’ll turn out to not suck has become a thing of the past.