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The fuel cell technology available today is a solution to a problem we don't have: an abundance of free hydrogen. The reaction between hydrogen and oxygen is potent enough to put the space shuttle in orbit. And water is the only exhaust (an exhaust that traps ten times the heat of CO2). However, hydrogen isn't easy to come by. The way we get it now is by processing natural gas from underground. The process is comprised of and uses fossil fuels. Hydrogen could be made using solar power electrolysis. For the sake of this page, we'll pretend the hydrogen used for the hydrogen electric vehicle comes from solar energy. Just play along with this optimistic scenario. Since this website is aimed at cars, that's what we'll focus on. I'm not going into detail about infrastructure shortcomings supporting a hydrogen fuel cell car (not here anyway). Like the electric and gas powered cars, I'll focus just on the efficiency of the hydrogen powered car. That is to say that we want to know how much of the stored energy is turned into kinetic motion. A comparison of efficiency between a hydrogen car, an electric car and a gas engine car shows the efficiency of energy conversion. For instance, a typical gas engine turns about 20% of the gasoline energy into motion. So a gas engine is 20% efficient. The efficiency of a battery is calculated by dividing how much energy comes out of the battery by how much energy was used to charge it (power out / power in). Batteries in use for this application may typically see a charging efficiency of 75% (power in), and a discharge efficiency of 80% (power out). The product of these efficiencies is 60% (75% x 80% = 60%). This means that 60% of the energy used to charge the battery is used to power the motor. For the sake of this exercise I'll assume the electric motors in the examples are like that of the Tesla Roadster. The motor in the Tesla Roadster is about 95% efficient. That's insane!
The hydrogen electric vehicle is similar to an electric car. Instead of storing electricity in a battery, it is stored in tanks of hydrogen and oxygen. Electricity "charges the battery" by electrically separating water into hydrogen and oxygen. This process is called electrolysis. At best, the process is about 50% efficient. And converting the hydrogen and oxygen back into electricity is also about 50% efficient. The end result is a vehicle that isn't any more efficient than a gasoline powered car. Who cares if its 24% efficient?! It'll be powered by renewable energy! The problem is that efficiency will be even more important in a renewable energy system. The source of energy (sunlight, wind and water) may be free, but the dams, solar panels and wind turbines that convert that energy to something useful will cost millions to trillions of dollars. Remember what I said on the home page: "Energy is free. Gasoline is cheap." There will be about 1/100 of the available energy from renewables that we are using today from fossil fuels. There will be a very large demand and very little supply in infrastructural renewables. Renewable energy is more scarce than oil. A renewable energy system cannot afford inefficiencies.
The simple battery powered electric vehicle is more than twice as
efficient as a hydrogen electric vehicle. This means that the electric
car will travel twice as far as the hydrogen car on the same amount
of energy. It also means that the hydrogen car owner will pay twice
as much for their car to go the same distance as an electric car. I'd rather use the hydrogen and pump it through a
gasoline engine than send it through a fuel cell. Bringing a piston
engine to life with a hydrogen conversion sounds like it would be
a lot more fun.
Converting a conventional gasoline car to run on hydrogen would be much cheaper than buying a hydrogen electric car made of expensive exotic materials.
What about the Honda FCX? It has a hydrogen fuel cell! If Honda is putting a lot of money into hydrogen fuel cells there might be something to it. Let's look at the data to see what's going on here. The website can be quoted "In gasoline-powered
vehicles, fuel (gasoline) is used to heat and expand air, which
then drives the engine’s pistons and crankshaft. Fuel cell
vehicles, on the other hand, are much more efficient, because the
conversion of fuel (hydrogen) to electricity, used to power the
electric drive motor, is a more direct electrochemical process.
Water is a by-product. This doesn't tell us anything. The specifications make no mention of stored energy in KWh. So the website brags about efficiency without letting anyone know what the real efficiency is. The Tesla Roadster website is very blatant about spelling out energy usage in specific quantities. The "Home Energy Station" presented on the website uses natural gas (fossil fuel) to create hydrogen. Okay, so we're already using fossil fuels to create solar panels, wind farms, and hydroelectric; why not hydrogen? Because the efficiency is like that of biofuels (corn as fuel). There's not really any appreciable return on the energy invested.
The Honda FCX Clarity uses a lithium Ion battery pack to capture lost energy and supplement the power generated through the fuel cell. The fuel cell is a bottleneck of energy flow. In order to accelerate, a conventional battery and/or capacitor must be used. This was not included in the comparison above because the amount of assist cannot be quantified. If the assist is 10% of the time with an efficiency of 50%, then that might bring the vehicle efficiency up from 24% to 26%. And that's only because the electrical assist system would be more efficient than the hydrogen system. There's no list price of the Honda FCX Clarity. It's just listed as a $600/mo lease. I think it's safe to assume that the price on FCX Clarity is north of $60 grand. That's not an economically friendly number. If something costs that much to make, then it consumed about that much value in resources which leads me to believe its not exactly as earth friendly as we would like to see. The Efficient-Mileage Rating given for the Honda FCX Clarity is an educated guess. I chose a number just a bit over average as a result of my arithmetic shown above. The number is seemingly arbitrary because Honda does not publish information relevant to the FCX's energy usage.
What is the Future of Hydrogen Fuel Cells? If improvements can be made in the efficiency of electrolysis (say 75% conversion efficiency) so that the fuel cell is as efficient as a battery, then the fuel cell will have a bright future. Batteries tend to be toxic or short-lived. Batteries and fuel cells will probably always be expensive. However, fuel cells are much cleaner than batteries and require less maintenance. The price needs to come down by finding an alternative catalyst to platinum and the electrolysis process needs to be improved. Hydrogen doesn't make any sense whatsoever if it is derived from fossil fuels. The public needs to understand that hydrogen is not an energy source. It is a way to store energy for short periods of time. Hydrogen leaks profusely through everything because it is so small. Using hydrogen for home appliances is wastefully innefficient because of the energy conversion. Home appliances will need to be efficient electric devices because it will be electricity that comes from solar cells, wind farms and dams. This means hydrogen could only be practical for transportation . . that is if it can rival the ye old battery for efficiency.
Editor's Note This wasn't exactly easy for me to write. Even though my heart is in American cars, I like Hondas. I think they're designed and built very well and even enjoyable to drive. My only complaint is that they gear their transmissions too low. Honda is a company seriously interested in helping the environment from the execs on down. The Honda FCX is a large investment made toward that end. But I feel the technology is on the medium-rare side. Maybe just a bit underdeveloped to be competitive. Maybe the FCX Beta program will be enough feedback to make the technology viable in round two. This may be a result of a common struggle within a company. Execs often want to shove new stuff out the door quickly to sell while the engineers would rather toil away perfecting their art. However I think Honda's Home Energy Station idea is completely misguided. I think the hydrogen car should carry its own electrolyzer so it won't have to depend on hydrogen stations. It could use the same wall sockets and water everything else uses. There would be no infrastructure to set up.
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