Fuel Cell Vehicles
Today, there are serious problems with our current transportation system. We rely mainly on gasoline powered cars to get us where we need to go. The problem with today’s cars is they still put out a lot of pollution and use up fossil fuels. Someday, we will run out of fossil fuels. For Americans, a gasoline-powered transportation means a dependence on foreign oil, much of which comes from areas that are politically unstable. People have been talking about running cars on water for ages. The reason is because gasoline is expensive, and causes pollution around us. So, what can we do to decrease the negative effects of our transportation habits? We could change the cars so that they use energy more efficiently, and pollute less. This could be done by using hydrogen as a fuel.
What is a fuel cell?
A fuel cell creates electricity through a reaction between hydrogen and oxygen as both gases pass through the cell. Unlike a battery which needs to be recharged, a fuel cell will continue to produce electricity provided hydrogen and oxygen are being introduced into a fuel cell with its only exhaust being water vapor. A fuel cell requires a constant supply of fuel and oxygen to produce power. It consists of two electrodes, a negative anode and a positive cathode which are separated from each other by an ion conducting electrolyte. The anode is where the hydrogen atoms from the fuel react to form positive hydrogen ions and negative electrons. The hydrogen ions migrate through the electrolyte to the cathode where they combine with oxygen from air to form water. The flow of electrons from the anode to the cathode produces an electrical current. The basic fuel cell reactions are:
Anode Reaction: H2
2H + 2e
Cathode Reaction: %02 + 2H* + 2e
Overall Reaction: H2 + 1/2O2 - H20 + electricity
History of fuel cells
The theory of fuel cells has been around for over 150 years. In 1839, English inventor Sir William Grove reasoned from his experiments splitting water into hydrogen and oxygen using an electric current, that it should be possible to react hydrogen with oxygen to produce electricity and water. The term fuel cell was first coined in 1859, when Ludwig Mond and Charles Langer attempted to construct a fuel cell using air and industrial coal gas as the fuel. In 1959, Engineer Francis Bacon demonstrated the first fuel cell device, a five-kilowatt fuel cell system, enough to power two homes. In the 1960’s, NASA began pursuing practical applications for fuel cells. NASA selected fuel cells as the power generator of choice for its first manned space mission. The fuel cell was selected over batteries, nuclear reactors, and solar power for several reasons: compact size, lightweight, high efficiency, ability to operate in zero gravity, emission of only drinkable water, and ability to operate for the lifetime of the mission (usually seven to fourteen days).
Ford and Daimler Chrysler have invested heavily into Ballard Power, one of the leading fuel cell manufacturers. These fuel cells require hydrogen. Since there is no readily available supply, the industry is considering steam-reforming fossil fuels such as natural gas and methanol. Even though the fuel cell is zero emission, the process of converting these fuels into hydrogen means the automobile would not be a zero emission vehicle.
The SHEC process uses an advanced solar-thermal chemical process to extract hydrogen and water. It provides a clean and renewable source of hydrogen. When the hydrogen is later consumed in an application, it is reclaimed in the Earth’s atmosphere as water vapor.
Hydrogen is the lightest element, with only one proton and one electron. Two-thirds of the planet is covered in water. Therefore, unlike gasoline, we will not run out of hydrogen. Hydrogen is also a much cleaner fuel than gasoline. Gasoline and other fuels like coal, wood, and natural gas, consist of carbon and hydrogen, so burning gas produces carbon dioxide and other byproducts. Burning just hydrogen, or using it to power a fuel cell, produces water with only trace amounts of other byproduct. Another reason for using hydrogen is that it is much more efficient than gasoline or other hydrocarbons, meaning we would cut down on the fuel being used.
Where will the hydrogen come from?
There is no risk that we will ever run out of hydrogen. It is the most plentiful element in the universe. On Earth, however, it exists naturally only in chemical compounds, not as hydrogen gas. Water and the main components of coal, oil, and natural gas are prime examples of these compounds. Natural gas currently provides most of the hydrogen used in the industry. The relatively simple technology employed—steam reforming—could also produce hydrogen gas for cars at central plants of filling stations. Alternatively fuel tanks could be filled with petrol or methanol, with the cars using on-board ‘reformers’ to generate hydrogen for their fuel cells. In steam reforming the hydrocarbon fuel reacts with water at high temperatures to produce hydrogen gas. A major drawback is that carbon dioxide and smog-causing gases such as nitrogen oxides are given off too, although emissions per kilometer of car travel would be less than from petrol-burning vehicles. An alternative approach under development is auto reforming. This should increase the attractiveness of on-board hydrogen production. It will allow the reforming to occur at much lower temperatures—too low for the production of nitrogen oxides.
Is it safe?
One hurdle that must be overcome
before we can begin using hydrogen for transportation on a large scale is the
public perception that hydrogen is dangerous.
‘Remember the Hindenburg’—that is a phrase often heard when discussing
hydrogen. This German passenger airship
kept aloft by hydrogen, crashed into flames as it came in to land at
How to Burn Hydrogen with Oxygen!
There are two main ways you can burn hydrogen with oxygen, to give you water, and energy.
· You can burn hydrogen in a modified car engine. Two companies, BMW and Mazda, are working on this. The engine works fine, but with 20% less power-which is pretty reasonable, considering that we have been working on the petrol engine for a century or so. When you burn hydrogen in an engine, you get mostly water coming out of the tailpipe. You also get small amounts of oxides of nitrogen (from the nitrogen in the air), and even smaller amount of hydrocarbons (from traces of the lubricants in the combustion chambers of the engine). Even so, a hydrogen-powered car is much less polluting than a petrol-powered car.
· An electric car is another way to use hydrogen to run your car. Mercedes-Benz has been using a fuel cell along with electricity to run the electric motors.
Hydrogen Cars: Fuel Cell Vehicles
Fuel Cell vehicles offer a solution to air pollution. A gallon of gasoline burned in an internal combustion engine releases 20 pounds of carbon dioxide. Also, the internal combustion engine produces nitrogen oxides, an air pollutant responsible for smog formation. Diesel exhaust from buses and trucks contains the same pollutants and particulates, which make the exhaust, look black. These particulates cause air pollution and even health problems in people. The federal government and many states are cracking down on air pollution by requiring a certain number of low emission and zero emission vehicles to be purchased per year over the next ten to twenty years. Fuel cell vehicles qualify as a zero emission vehicle since their only emission is water. The following are some examples of hydrogen prototypes:
Partner General Motors and
General Motors car company Holden has created a car called the HydrGen1. This hydrogen powered car has set new endurance records when it was being tested in May of 2001.
BMW's fleet of liquid hydrogen-fueled
7-Series sedans at Paramount Pictures studios in
Right now Motor Companies are introducing prototypes for Motor Shows. Fuel cell vehicles are not expected to be available to the public for at least 15 years.
There are several advantages of hydrogen cars over gasoline cars. The first is that hydrogen is a renewable energy source. It can always be made and we will never run out. Secondly, the combustion reaction of hydrogen produces zero emissions. Hydrogen puts less wear and tear on the cylinder walls of the engine, because it does not dissolve the lubricating oil. Its high dissipation rate helps it mix with air and spread out quickly in the cylinders so that it combusts 50% better than gasoline. These cars have a 25% efficiency compared to the 19% of gasoline engines. The efficiency is expected to be higher if water vapor is added to the cylinders to increase the expanding power. Hydrogen has three times the energy of octane in gasoline. No more smog forming exhaust gases, no more carbon dioxide emissions that contribute to global warming, and no more worries about diminishing oil supplies and rising prices.
Hydrogen is difficult to store. This is because at normal temperatures hydrogen must be packed tightly into a car’s tank; otherwise a filling stop will be needed every few kilometers. The obvious solution is to strongly compress the hydrogen, or liquefy it. However, large amounts of energy are needed for this—an estimated 20-40 per cent of the energy content of the fuel. Also, tanks designed to hold hydrogen at extremely high pressures, or at temperatures approaching absolute zero, are heavy and expensive.
Recent technological advances, particularly in fuel cell design, have made hydrogen powered cars a practical proposition, and car makers expect to start mass-producing them within the next decade or so. Their power and acceleration should match those of today’s petrol-powered vehicles, but they might need to be refueled more often.
The best ways to produce, distribute, and store the hydrogen still have to be sorted out. In short term fossil fuels may remain in demand as a hydrogen source. However, the idea that most of us will be driving non-polluting cars fuelled by hydrogen from a clean, renewable source is no longer a flight of fantasy.