In a perfect world, all energy would come from electricity and hydrogen. Wind, solar, tidal, geothermal, and other renewable energy sources would provide enough electricity to power everything except air transportation. The “conventional” answer to transportation in the future was the hydrogen fuel cell. It doesn’t get any better than that. The fuel cell burns hydrogen and powers cars, trucks, and any other transportation vehicle. The hydrogen combines with oxygen to form water vapor. No other gases or pollutants are released.
The hydrogen fuel cell is an efficient generator of electricity, but it has one major problem: It needs hydrogen. So where does it get it? Therein lies the hydrogen myth. On Earth, there’s no hydrogen to mine. You have to make it, and that requires wasting energy. You could conceivably mine hydrogen from the sun or Jupiter, but even Al Gore would probably agree that that would be tough to accomplish.
Last month, the Department of Energy (DOE) finally conceded that hydrogen won’t be a part of the near-term solution to global warming, the peak oil crisis, or anything else you can think of. They’re cutting back funding dramatically on hydrogen research. This is a triumph of physics over policy. In the long run, physics will always win, but we have way too many policy wonks in Washington without a clue about how the physical world works.
Even if hydrogen could be produced cheaply, it has another problem that makes it impractical as a fuel for transportation. Even when highly compressed, the energy density per liter or gallon is very low compared to gasoline or diesel fuel. Think about the size of the fuel tanks on the trucks that deliver gasoline to a station compared to the size of the tank on the truck. The ratio is about 90 to 1. That’s an efficient delivery system. If a hydrogen delivery truck had to burn hydrogen, the size of the fuel tank for the engine would be about one-quarter of the size of the delivery tank! Energy density or transportation problems didn’t kill hydrogen. What killed it is the deliverable amount of energy to the wheels of a vehicle compared to a battery solution. This is why we won’t be seeing hydrogen-powered cars from Toyota (TM), Honda (HMC), or Ford (F).
The table below needs a little explanation. It starts with 100 kilowatts of electricity from renewable sources — solar or wind for example. It then compares the steps required to get the electrical energy stored on a vehicle as either hydrogen or batteries. During each step, energy is lost — generally as heat — until electric power is driving the electric motors on a hydrogen fuel cell vehicle or a battery-powered vehicle. Each step shows the percentage efficiency and the remaining energy left after each step.
This table used data from an article published by Ulf Bossel entitled, “Does a Hydrogen Economy Make Sense?” in Proceedings of the IEEE, Vol. 94, No. 10, October 2006. You can argue all you want about the exact percentages used in each step, but the result won’t be much different. A battery-powered vehicle will be close to 3 times as efficient as a hydrogen- powered fuel cell vehicle.
The DOE got it right.
If the one word back in the 1967 movie The Graduate was “plastics,” the word for the future will be “batteries,” with the possible addition of “ultracaps.” I’ll discuss batteries and a potential “ultracap play” in a follow-up article.
This post originally appeared on Minyanville. See other Minyanville stories on this topic:
- 10 cars that sunk Detroit
- Electric cars: Be careful what you wish for
- Pimp my hybrid
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