Hydrogen as an Automotive Fuel
As a result of climate change, you have just replaced your gas-guzzling SUV with an ultra fuel efficient hybrid car because you care about the environment, but there is still in the back of your mind the thought that while you are using less gasoline, you still have no choice in the matter- you are still obliged to carry on using gasoline until a fuel comes along that has no harmful emissions. However, is such a fuel even possible; is it possible to create a fuel that contains more energy per any given volume than any other alternative fuel in use today, and yet has no harmful effects on the environment?
Well, it might be possible. In fact, such a fuel already exists in the form of hydrogen, but is it a viable replacement for the fossil fuels currently in use? Again, it might be, but all energy sources have drawbacks, and in the case of hydrogen as an automotive fuel, the downside is the production of carbon dioxide as a waste product, which goes some way towards negating the “no harm to the environment” claim of its proponents. Therefore, to help you understand the issues, we have outlined the pros and cons of hydrogen as an automotive fuel, albeit very briefly.
What is hydrogen?
Hydrogen, which is denoted with an “H” on periodic tables, is the most abundant element in the Universe, so it should be easy to turn it into an automotive fuel, right? Well, not really, since hydrogen does not occur naturally in a pure form on earth- if it did, everyone would be using it. The fact is that hydrogen only occurs in combination with other substances, the most notable of which is water, which consists of hydrogen and oxygen. Other notable compounds in which hydrogen is present is coal, methane, natural gas, and as a constituent in almost all forms of biomass.
To obtain hydrogen for fuel, it first has to be extracted from the compounds in which it occurs, and today, this is most commonly accomplished in a process called “steam reforming” in which the hydrogen atoms are detached from the carbon atoms in methane. This process accounts for around 95% of all hydrogen produced today, of which approximately 10 million metric tons are produced in the USA annually. If this amount of hydrogen is taken at its calorific value, which is twice that of gasoline, it is enough to fuel all the vehicles in the USA today. However, this process releases large amounts of carbon dioxide into the atmosphere, which has serious negative impacts on the environment.
Another method of extraction is called “electrolysis”, and it involves separating the hydrogen from the oxygen in water. This process uses electricity and while its proponents claim that it involves no harmful emissions, the fact is that vast amounts of greenhouse gasses are released during the generation of the electricity required to manufacture clean burning hydrogen. Moreover, the sheer amount of electricity required to manufacture hydrogen makes the process expensive to the point of it not being a viable option for large sale hydrogen production.
Hydrogen Fuel Cells in Cars
While hydrogen as a gas is not a viable fuel at present, hydrogen is at the heart of fuel cells for automotive use. In short, hydrogen is released from water using the electrolytic process, after which it is converted into electrical energy by a rather complicated process to drive electric motors via rechargeable batteries, much like the system in the hybrid car you have just purchased.
However, the amount of electrical energy produced in this way is not sufficient to allow for say, cross county trips. Most hydrogen powered cars have ranges of less than 200 miles, and the performance of these cars is lackluster at best. In addition, there exists virtually no infrastructure to service fuel cell-powered cars. The United States has at present only about 50 hydrogen stations (mostly in Southern California), which translates into the fact that for as long as there is no infrastructure, there will be no hydrogen fueled cars because they cannot be refueled.
How Safe is Hydrogen as a Fuel?
Hydrogen is safe enough considering the fact that millions of tons of it are produced and transported on American roads without incident. In fact, Toyota has performed extensive tests on the Mirai, and by all accounts, it passed all tests with flying colors. Below are listed some of the tests and their results.
- At just 260 lbs heavier than the existing Camry hybrid, the Mirai is several hundred lbs lighter than pure electric cars with ranges of about 200 miles.
- The hydrogen tanks inside the Mirai is made from ultra strong fibers similar to carbon fiber, and they are capable of withstanding singe impacts even from .50 caliber bullets while being pressurized to as much as 10,000 psi. One such tank ruptured only after being hit by a .50 caliber bullet twice in the same spot.
- Repeated crash tests at varying speeds showed that the fuel cell and hydrogen tanks were more crash resistant than the steel structures that are meant to protect them. In every test, the protective structures failed before the tanks and fuel cell did.
- Toyota logged more than 1 million successful test miles in temperatures ranging from below freezing to more than 1000F, proving the efficiency of fuel cells in all temperatures.
- Fuel sells tested in the Mirai were found to effective for around 5000 hours, or 150,000 miles of use.
The Future of Hydrogen as Fuel
While the cost of producing hydrogen for automotive use is at present comparable to that of gasoline and diesel, the biggest issue is the lack of suitable infrastructure. While it is true that large quantities of liquid, as well as gaseous hydrogen can be transported safely, the only viable method storing quantities large enough to fuel the national fleet is to store it in liquefied and pressurized form. At present, there are no facilities anywhere in the world to store hydrogen in very large volumes, which means that there is also no reliable means of distributing it. Proponents of hydrogen as an automotive fuel claim that the required infrastructure will cost no more than the existing distribution network for fossil fuels.
Nonetheless, the existing network was constructed over a period of more than a hundred years, and the cost was shared among all the players in the field. With hydrogen, there are not that many players, and while most makers of hydrogen powered vehicles are presently giving hydrogen away for free to users who buy or lease their vehicles, this is not enough to create the awareness required to spur large scale investment in new infrastructure. And in particular, not by current players in the field who still have very large vested interests in producing and selling fossil-based fuels.
For the moment then, it appears that hydrogen as an automotive fuel is dead in the water so to speak, and unless a sudden, and severe, oil crisis occurs that could possibly reinvigorate the hydrogen industry, it is likely to remain dead in the water for the foreseeable future.
