Hydrogen Oblivion

With the recent run-ups in gasoline prices, there has been much talk about hydrogen-fueled vehicles along with other alternatives. Popular opinion seems to believe hydrogen is a substance that can somehow defy the laws of physics and provide everyone in the world with an unlimited supply of cheap energy produced by pollution-free renewable energy sources.

While I certainly believe that we can provide more energy than we should ever need through renewable resources, converting it all to hydrogen is probably not the way to go. Thermodynamically, it doesn't make much sense.

My car runs on water!

When we talk about "running cars on water", there is concern to be raised. I say "You can't run a car on water, because water doesn't burn and doesn't have any energy potential in it!". They then state that "Yes, but they use water to make hydrogen, and hydrogen can power vehicles!"

It is certainly possible to run a vehicle on hydrogen, but breaking water into its basic elements is a process which requires a large input of energy. There's no "free lunch" by running the vehicle on hydrogen, it is simply another way to get the required energy into the vehicle. Hydrogen is a storage medium, like a battery. We "charge it up" by creating hydrogen from water, and then we discharge and use the energy by oxidizing the hydrogen back to water. So in order to turn water into hydrogen, you have to put energy in the form of electricity or very high-grade heat into the water in order to split the oxygen and hydrogen atoms apart. Once they are split, most of the energy that you put into the water is now stored up as chemical potential in the hydrogen. All it needs is some oxygen and an ignition source, and BAM!...it'll all be released, giving you lots of heat and water all over again. There are no magical gains - we still will need our arsenal of fossil fuel, nuclear, and renewable generation schemes to get the actual energy.

The only real way to "run a car on water" would be to power it using electricity from a hydroelectric plant. Even hydro plants simply use water as an energy carrier, as it is really solar energy, where the sun evaporates water which rises into the sky, and when it condenses it falls back down and the gravitational potential energy that comes along with falling is captured when the water is routed through a hydroelectric plant's turbines.

Hydrogen vehicles that are currently in development use hydrogen obtained from the reforming of natural gas: the energy comes from natural gas. Coal and petroleum can also be used to create hydrogen through a thermochemical reaction. Hydrogen made using electricity from renewable sources comes from solar or geothermal energy, and it can be also made using nuclear energy.

Moral of the Story: YOU NEED TO PUT ENERGY INTO WATER TO GET HYDROGEN OUT, and you will get less energy out than what you put in.

Is Hydrogen Practical?

I do believe hydrogen is practical provided that we are willing to build up the infrastructure, spend trillions of dollars, continue to surrender to large, centralized energy providers, wait decades, and that we can store enough hydrogen in vehicles to travel a reasonable distance. Such will have to be considered along with alternatives which include combinations of electric vehicles, pedal/electric bicycles, pedestrian-friendly cites and towns, rail lines, general modification of lifestyles to be less automobile-dependent, etc.

But if we are going to generate electricity to power vehicles, why not use it to charge a battery which drives the vehicle directly? The fewer conversion steps that are in the process, the more efficient it will be. Electric vehicles can take advantage of the existing electrical infrastructure and they can be refueled at home, or in parking spaces with charging stations. Hydrogen would require an entire new infrastructure of fueling stations, pipelines, and hydrogen production facilities. The high-volume, low-density gas does not lend itself to easy transport. The equipment necessary for hydrogen production is very costly and would likely not be affordable by communities who would like to become energy independent by producing fuel from their own distributed generation facilities. Currently, batteries are much more economical and practical to produce than fuel cells/hydrogen tanks. Electric vehicles could be on the road today. Hydrogen would be quite a ways off.

Such electric vehicles may reduce liquid fuel consumption by 80 percent (provided that people actually plug them in) and with advances in battery technology, liquid fuels would really need to be used only for long-haul and heavy-duty vehicles.

CREATED/WRITTEN: 2006-04-30 00:00