A fleet of cars, flying down Americas highways, emit naught but drops of water that sprinkle the roadway like icing on a cake. The atmosphere, reeling with the cool relaxation of zero carbon emissions, breathes easy, showing off its best shade of blue. Gone are the days of burnt, black freeways. Gone are the days of coughing, sputtering SUVs. Gone are the hazes that blur our skylines and warm our oceans.
This is the dream of the Hydrogen Highway and its a popular dream. Fuel cells are a hot topic of clean energy discussions. The big automakers, even two years ago, had hydrogen-powered cars that could travel 300 miles on 17.6 pounds of hydrogen, reaching speeds up to 132 miles per hour. Furthermore, hydrogen has roughly three times as much energy as gasoline.
As our need for fossil fuels steadily increases, while supplies of such fuels steadily decreases, our need for alternative fuels becomes increasingly desperate. So where are all the hydrogen cars? Why do we continue to pay high gasoline prices and buy marginally more efficient gasoline-powered automobiles when free and abundant water could easily power our on-the-go lifestyles?
Production of hydrogen for fuel applications can be achieved in a variety of ways, including natural gas, coal gasification, biomass gasification, electrolysis, and others. Most of the hydrogen in production today is manufactured from natural gas or coal, minimizing its true effect on reducing greenhouse gas emissions. There is no reason that hydrogen for fuel cells could not be made from renewable energy sources, such as solar or wind. The problem is renewable resources are simply not yet utilized enough to facilitate mass production of hydrogen.
Electrolysis, or the act of using electricity to separate hydrogen from oxygen to create gas, is a popular, if underdeveloped, solution. In fact, electrolizers are often homemade and can be constructed inexpensively to supplement gasoline in the average car. This, many argue, is the avenue to free energy for your car. It faces two big obstacles: big automakers and oil companies are resistant to free energy for existing cars and electrolysis is the most inefficient way to produce hydrogen.
As a matter of fact, hydrogen is not a fuel. It is a way of storing or transferring energy. That is why production is such a key issue for a hydrogen economy. On that note, there are three ways to store hydrogen: liquefaction, compression, or solid-state. Liquefaction is the act of cooling hydrogen until it is near absolute zero, where it turns liquid. Compression involves storing room-temperature hydrogen in a tank at up to 10,000 psi. Just eight kilograms of compressed hydrogen was enough to power GM’s Sequel for 300 miles. Solid-State storage involves materials called metal hydrides which can capture hydrogen molecules and then release them on demand. Solid-state storage is still very impractical (a 700 pound tank holds but a few hours fuel), although research continues into more practical possibilities.
Distribution and infrastructure are a big problem for the hydrogen economy. Being so light of weight makes hydrogen difficult to capture. It also has the nasty habit of embrittling and weakening steel. Nonetheless most hydrogen right now is transported via trucks or trains. Pipelines are also used to an extent, but treating the steel to prevent embrittlement is an expensive task. Producing hydrogen locally or on-board would eliminate these problems, although today most locally produced hydrogen is tied to natural gas or coal plants, still leaving greenhouse gas emissions as a prominent problem.
Many proponents argue for a hydrogen economy in which the worlds simplest element could power not just our cars but our homes and businesses…our daily lives. Yet as a clean energy source, hydrogen power cannot go it alone. It simply takes too much energy to produce and, as long as that energy is derived from natural gas, coal, or even nuclear power, hydrogen will not compete with cleaner, more direct renewable resources such as wind or solar. However, hydrogen fuel cells certainly show promise when combined with other forms of energy. In fact, it may be the key to storing solar electricity in the home.
The biggest problem for hydrogen so far is simply that it has to be made. It is a carrier, not a primary source of energy. This makes it too reliant on other forms of energy which, at this point in time, are mostly fossil fuels. Expect, however, hydrogen to ride proud and high down the renewable highway as solar, wind, and other renewable resources gain a stronger grip on energy usage.