If you were paying attention for the last couple of years, the European car makers have shifted their focus to making diesel cars for the North American market. Smaller four-cylinder cars will be getting upwards of 50 mpg on the highway while producing similar or even less emissions than a comparable gasoline engine. The beauty of diesel is that the infrastructure is already here. Diesel may not be quite as common as gasoline, but it is still readily available and widely produced.
Honda, however, has a different idea. The Japanese automotive giant wants the future to be here now and has launched a hydrogen fuel cell vehicle for public consumption. The idea of the fuel cell has been around for over 160 years. The concept is simple: Take the energy available from chemical reactions and translate it into work. Still sounds like gasoline doesn’t it? The difference is a fuel cell generates electrical power that then powers an electric motor to create the work. It is important to point out now that a fuel cell is not a battery.
A battery stores power and releases it; a fuel cell generates it with consumable materials. The most common form of fuel cell is the hydrogen variety. As you have hopefully seen, by placing two electrodes in water you can separate the hydrogen from the oxygen and create two separate gases. Well, if you reverse the reaction to create the water, the electricity flows out. So if you can fill a car with the two gases, a fuel cell and an electric motor, you suddenly have a powertrain. The real beauty is that the only byproduct belching out of the tailpipe is water. Unfortunately, with current conditions, the only real purpose a hydrogen fuel cell vehicle is going to serve is making your neighbor with a Prius feel like they’re driving a 16-cylinder musclecar upholstered in baby seal.
Currently, the cheapest and easiest way to get hydrogen is by refining it out of fossil fuels. Yeah fossil fuels, the same stuff they make gasoline and diesel out of. Even better, it takes more energy to get the amount of hydrogen that would have the equal amount of potential energy of diesel. The cleanest way to get hydrogen is through electolysis, the two-electrode method mentioned earlier. Unfortunately, it requires a huge amount of electricity. If that electricity is produced by a nuclear plant or even better, wind or solar, then the net energy equation actually is cleaner than a gas or diesel car. However, most of our power is from fossil fuel, which makes it dirtier than a clean-burning car.
If you consider that the hydrogen production process is only about 50 percent energy efficient you are losing half your energy there, but we aren’t done. You still have to get the energy to produce that hydrogen. As stated already, if you can do it with a form of clean energy you are good, but combustion fueled powerplants are only about 40 percent efficient. Now you have to get the fuel to the people. Hydrogen may be more efficient by weight than fossil fuels, but not by volume. A gallon of gasoline weighs roughly 6 pounds and contains 125,400 Btu, a gallon of diesel weighs just over 7 pounds and contains 139,200 Btu of energy, a gallon of liquid hydrogen weighs just 0.567 pounds but only has 34,643 Btu. The hydrogen fuel tank is also substantially heavier because liquid hydrogen has to be kept below minus 253 degrees C or else it needs to be vented since it turns back into gaseous hydrogen.
After all of this you would think I am completely against hydrogen but I’m actually a big fan. Hydrogen is one of my favorite gases, right behind helium and argon. My problem is the same as it is with electric cars. We aren’t really solving any problems, just moving them around. We have to figure out how to make hydrogen easier, cheaper, and cleaner to produce. Right now, estimates for the cost of an equivalent amount of hydrogen compared to gasoline would be between $6-$10 per gallon. Estimates put the cost of developing the United States infrastructure for hydrogen anywhere from $500 billion to a cool $1 trillion. This sounds like a lot but we are never going to get there if we don’t start. In the short term, diesel is going to make a lot more sense, but I applaud Honda for trying something new. The technology has to be developed somewhere and the infrastructure won’t be developed until there is demand. My next car will likely be diesel, but who knows, less than 10 years from now, we may very well be carving canyons in my own personal water factory.
