Will we ever use hydrogen as a vehicle fuel? The answer is yes because when the price is right we will switch to hydrogen since it has many advantages.
First of all, when combined with oxygen the only exhaust that will come out from the tailpipe is plain water. It is a non-polluting fuel. Secondly, the efficiency of the chemical reaction process can be quite high, meaning less thermal waste and less addition to warming the Earth. Thirdly, we can always make hydrogen gas, it is completely universal and cannot be controlled by any country.
Although hydrogen is the most abundant element in our universe it is not a fossil fuel and can be considered “renewable” if the proper technology is used for its manufacture, such as solar energy.
So why are we still using dirty hydrocarbons to power our vehicles? The answer is simple, nobody has yet found a way to safely store the hydrogen gas in a vehicle. Of course you can compress the hydrogen to 5,000 psi but who wants to drive around with a dangerous “welding tank” underneath your car that could shoot off like a torpedo if the piping is ever broken during an accident?
There are some metals like palladium that can soak up hydrogen gas into their structure much like a sponge soaks up water. For example, by placing a brick of palladium metal in a pressurized tank of hydrogen the pressure will drop after a while as the hydrogen molecules mosey into the palladium’s atomic stacking structure. Unfortunately, palladium costs nearly $1,500 a Troy ounce, almost as much as gold, so we can rule this metal out.
In the attempt to reasonably store hydrogen gas, an international team of researchers, lead by Professor David Antonelli of Lancaster University, has announced their discovery of a new material made from manganese hydride that could be used to make molecular sieves expressly for use in fuel tanks. Since manganese is only $10 a pound, the prospect of an inexpensive storage system is finally possible.
As published last week in the Royal Society of Chemistry bulletin, Energy and Environmental Sciences, the manganese compound would enable the design of tanks that are far smaller, cheaper, and more convenient to use than existing hydrogen fuel-holding technologies.
Before we go into the storage technology let’s compare a hydrocarbon-based fuel such as gasoline against one using just hydrogen. In the standard automobile engine, working on the Otto thermodynamic cycle, an overall efficiency of 30% is usually claimed as the best as you can get, meaning most of the energy goes out of the exhaust pipe into the environment. In the past several years some improvement has been made and cars with gasoline direct injection show increased efficiency to 35% but this is really not much of an improvement.
On the other hand, a hydrogen vehicle would use an electric motor powered from a hydrogen-oxygen fuel cell. This combination, an old technology and used by NASA for the past 50 years, can produce electricity with an efficiency up to 60% and the exhaust is still ordinary drinking water.
To achieve a driving range greater of, say 300 miles, comparable to a normal fill-up at the gas station, about 12 pounds of hydrogen gas is required. Up to now, the idea of storing that amount of hydrogen in a tank pressurized to 5,000 psi requires holding 66 gallons in a tank about the size you would have outside your house for kitchen propane, only with a very thick steel wall. As said earlier, most people would object to driving a vehicle holding a tank that could explode into a fireball like the Hindenburg.
The researchers on this project say that by using a material known as Kubas manganese hydride, which can be prepared in a few simple steps from inexpensive components, the hydrogen storage may be sufficient to meet or surpass the US Department of Energy’s ultimate system target of 5 pounds of hydrogen per cubic foot of tank.
Their invention uses the discovery by Gregory Kubas of Los Alamos Laboratories who in 1984 found that certain organometallic complexes had the ability to soak up a hydrogen molecule (two atoms of hydrogen covalently bonded together) instead of just a hydrogen atom (as the expensive palladium does). This special binding allows higher storage capacity for the hydrogen gas within.
One good feature is that the new material can store the hydrogen reversibly under ambient conditions and is thermodynamically neutral. The mechanism will not require extensive engineering to utilize in on-board storage. It is said that the process works at room temperature.
The research team stated that this material could also be used to power ocean-going ships in a switch from diesel fuel to hydrogen. Perhaps within 10 years there will be hydrogen dispensers alongside of gasoline and diesel pumps.