Hydrogen as Automotive Fuel

Many of us have been told, and have figured out that about the only fuel that doesn’t give off carbon dioxide as it burns is hydrogen. So it would make a great fuel for a motor vehicle, right? Well, as with everything, it is a good news/bad news story.

Hydrogen does indeed burn nicely, giving off water vapour and heat. Most current internal combustion engines can burn hydrogen with relatively minor modifications to the carburetor, and there would be no need for a catalytic converter. However, there are two big issues about hydrogen: how do you make it, and how do you store it?

Almost all industrial-scale hydrogen is currently made from natural gas, or methane. This process generates carbon dioxide as well as hydrogen. If we are thinking about hydrogen as a motor fuel, we will need more methane than is currently available, and we will generate a lot of carbon dioxide. So… how else can you make hydrogen? You can pass electricity through water, and you get hydrogen and oxygen, lots of both. But you had better have your own generating plant, because you will need a lot of really cheap electricity. You don’t really want to burn anything to make your electricity, such as coal, oil, or natural gas, as you will make more carbon dioxide, so you are stuck with hydro and nuclear, our current favourites, or perhaps wind, solar, or tidal electricity, none of which gives enough power, at current generation efficiencies, to do the job. Fusion power is several years in the future at least. Seeing as we have dammed most of the rivers that are suitable, we are looking at nuclear – generated electricity as the most practical option. I know nuclear – generated electricity is like a red flag to a bull to many members of our community, but let cool heads prevail and let’s discuss it in reasonable terms (in another column).

After you have made your hydrogen you need to be able to carry enough in your vehicle to give about 400 – 500 km. driving. The current methods include a large high pressure (200 to 350 atmospheres, an atmosphere is about 15 psi) tank, weighing up to hundreds of kilograms, or a lower pressure tank (10 to 100 atmospheres) containing metal hydrides, which store hydrogen like a sponge, and give it up with gentle heating. GM, Toyota and Honda are all researching various promising hydride technologies. Both of these storage systems are going to fill the trunk of a standard car or mini-van. Another method of hydrogen storage is as a cryogenic (very very cold) liquid. This gives a greater energy density, but at the expense of having to cool and compress the hydrogen to begin with, then having to insulate the tank, which would be at about -250°C. Another issue would be filling your tank, not simply a matter of sticking a nozzle in a trapdoor in your rear fender as we are accustomed to doing. As technologies emerge, the infrastructure will need to be put in place to make hydrogen motor fuel available in the right form, requiring huge investments by supplying companies. Governor Schwarzenegger of California and Premier Campbell of British Columbia have just committed to a “hydrogen highway” from Los Angeles to Vancouver, with hydrogen fuel available along the Pacific Coast. There is also the huge psychological obstacle I’ll call the Hindenburg Factor – remember the German dirigible which crashed and burned spectacularly in 1937 (or the movie of the same name in 1975) and many people will say “No way!”. Having said that, the hydrogen industry as it exists today has an excellent safety record.

Despite these rather daunting technical challenges, several automobile manufacturers are going ahead with hydrogen-fuelled vehicles. BMW plans to introduce the Hydrogen 7, which will incorporate an internal combustion engine capable of running on gasoline for 500 km., or hydrogen for 200 km. Ford is marketing the “Edge”, a crossover SUV that is powered by plug-in hybrid fuel cell system that runs on hydrogen in a high pressure tank and goes 325 km between fill-ups. Not sure where they will fill it up in Brockville for a while yet.

One of the more promising areas where hydrogen-fuelled vehicles will be the right choice is urban transit. Buses work in a clearly-defined radius, they return to a central location where specialised fuelling can be set up, they work in cities where air quality can be a serious issue, and they are large enough to have room for special storage tanks.

So where does all this leave us? It is easy to say that hydrogen is the fuel of the future, and is pollution-free, and indeed it looks great on the surface. But as we can see, there are many issues and technological hurdles to be overcome before we can bid the gasoline and diesel internal combustion engines goodbye.