Disadvantages of Hydrogen Fuel Cells

Hydrogen fuel cells are the wave of the future. At least that is what many would want you to believe. They have a point because a hydrogen fuel cell is a novel way to power a car. The car would require no gasoline, run on hydrogen and its only waste would be water, a natural and safe emission. However, it is not a perfect science by any means and too many times there is talk about all the great advantages without any discussion of the disadvantages of hydrogen fuel cells.

With anything, there is going to be drawbacks. If it were such a perfect technology, don't you think every car would have one by now? Besides being expensive, the hydrogen fuel cell creates certain problems that haven't been completely tackled yet.

Here are the three main disadvantages of hydrogen fuel cells:

1. It's big and cumbersome. Your gas tank already uses a nice portion of your car, but a hydrogen fuel cell will be three times bigger than a gas tank. But that is not that all. The fuel cell has to be insulated to keep it safe and protected.

2. Safety issues. Liquid hydrogen has the ability to freeze air. There have also been reports of accidents with the fuel cell itself. Sometimes a valve will get plugged up when there is too much pressure in the cell. The only place to go is out, and the cell explodes. There is no way of knowing, yet, if this problem can be fixed, but there are many working on it. In a car accident, the tank might rupture, but the good news is the hydrogen will evaporate quickly. However, it is a more serious condition in a closed area such as a garage.

3. The hydrogen evaporates. Strange, but true. The insulation is not a perfect process and the hydrogen evaporates out of the cell at roughly 1.7 percent a day. This means that eventually cars are going to need a fill up. What? You thought you never had to use a pump again? The other problem with this is gas stations don't sell hydrogen. You will have to find a customized fueling station or work something out with the manufacturer of the car. Cars that are blends with fuel cells and gasoline will never have to worry about being stranded.

General Motors Co., currently has the Chevy Equinox Fuel Cell, one of the first fuel cell vehicles of its kind. If you are thinking about purchasing a vehicle of this type, speak to the manufacturer of the disadvantages of hydrogen fuel cells. By having the technology, they are aware of the pitfalls of hydrogen fuel cells and have begun work on how to make it better.

The good news is that automobile companies are working at ways to make this a safer environment by creating less emissions and the more we learn about alternative methods, the better the Earth will be for it. Just don't go blindly in one direction without asking questions. Learn about the disadvantages of hydrogen fuel cells before you agree to use it.

How Hydrogen Engine Work

As gasoline and diesel prices at the pump continue to soar, automobile manufacturers are working tirelessly to produce vehicles that are capable of utilizing alternative fuel sources for power. One such alternative is hydrogen powered vehicles.

Although very few hydrogen powered vehicles are currently available, many car companies have plans to release them in the very near future. With the prospect of creating higher fuel efficiency and thus realizing consumer savings, it is interesting to understand how hydrogen cars operate and will be a viable option in the future.

Hydrogen engines depend upon a chemical reaction to create power to operate a vehicle. It's actually a very simple process - what happens when two particles of hydrogen combine with one particle of oxygen? H20 equals water! In fact, in a hydrogen engine, hydrogen and air are continuously fed through, combining to produce both the electricity necessary to propel a vehicle as well as the water that will be the vehicle's emission.

So in addition to hydrogen becoming an alternative fuel source, it also helps avoid dependence on fossil fuels, it is also a clean fuel source, where the emission is simply water instead of the far more harmful carbon dioxide produced by gasoline or diesel engines. Hydrogen technology so far is advancing at a much slower rate than ethanol, electric and natural gas engines but still has a very good outlook as a viable power source for the future.

Hydrogen Effects on ICE Components

Internal combustion engines (ICEs) offer an efficient, clean, cost-effective option for converting the chemical energy of hydrogen into mechanical energy. The basics of this technology exist today and could greatly accelerate the utilization of hydrogen for transportation.

It is conceivable that ICE could be used in the long term as well as a transition to fuel cells. However, little is known about the durability of an ICE burning hydrogen. The primary components that will be exposed to hydrogen and that could be affected by this exposure in an ICE are (1) fuel injectors, (2) valves and valve seats, (3) pistons, (4) rings, and (5) cylinder walls. A primary combustion product will be water vapor, and that could be an issue for aluminum pistons, but is not expected to be an issue for the exhaust system except for corrosion.

There is clear evidence that the components of an engine burning hydrogen could experience durability issues because of their exposure to hydrogen or its primary combustion product, water vapor. High-efficiency conversion of hydrogen to mechanical energy will require the use of direct injection of hydrogen. This requires the injectors to be exposed to hydrogen gas, where the tool steel or carbon steel components could experience hydrogen-induced cracking or embrittlement. This is especially a concern for the injector needle and seat, which will also experience impact and cyclic loading.

Piezoelectric actuators are one method for providing the fuel injector needle its lift, and there is some evidence that hydrogen could affect the performance of these components. Hydrogen could affect the dielectric properties of the piezoelectric material, the epoxy in which it is encased, or the electrical contacts. Testing is in progress on these components that should provide the data needed on their performance and methods for improving their durability should that be necessary.

Valves and valve seats will be exposed to hydrogen at elevated temperatures and could experience decarburization; however, it is difficult to predict their behavior based on current information. The operating temperatures of exhaust valves and valve seats for gasoline ICEs are at or below that at which decarburization occurs in carbon steels, but they are generally made from alloy steels that have higher decarburization temperatures.

Also, the operating temperature of a hydrogen ICE may differ from a gasoline ICE. Gasoline ICEs utilize aluminum pistons, and it is known that aluminum and aluminum alloys experience hydrogen embrittlement when exposed to water vapor at 70°C and above. This operating temperature is certainly within the range of engine operation, so that it is important that this issue be evaluated.

Hydrogen Internal Combustion Engine

The volumetric energy density of H2 is less than that of gasoline. Therefore, to provide the same driving range, the hydrogen fuel tank needs to be three times the size of a gasoline tank. Today, a typical passenger car has a range of 575 miles and is provided with an 18-gallon tank, whereas an 18-wheeled semitruck has a 750 miles driving range and requires two 90-gallon tanks.

Actually, the volume of the hydrogen tanks can be somewhat smaller than three times because the efficiencies of hydrogen IC and fuel cell engines are better than the efficiency of gasoline engines (gasoline, 25%; hydrogen IC, 38%; and hydrogen fuel cell, 45–60%).

BMW, DaimlerChrysler, GM, Honda, and Toyota are in the process of placing both IC and fuel cell units into the hands of ordinary drivers to gain experience and to collect data. Their prototype units cost about $1 million each. The manufacturers aim for a “pilot commercialization phase” by 2010–2012 at a unit cost of $250,000. They expect full production by 2013 at a unit cost of $50,000, and this cost will drop as the volume of production increases.

The list of vehicles that can run on H2 is constantly growing. Quantum Fuel Technologies Worldwide converted Toyota Priuses to hydrogen fuel. BMW is marketing its 7 Series, 12-cylinder, 260-horsepower car with an IC engine that can burn liquid hydrogen or run on gasoline, whereas the BMW 750 hL is designed to burn liquid hydrogen. The IC engine of the Ford E-450 shuttle bus burns 5,000 psig hydrogen gas.

In connection with using H2 as a fuel for transportation, there is a lot of activity, but no firm direction or conclusion yet. In Iceland, one can rent a hydrogen-fueled car from Hertz. In Japan, as part of its national hydrogen program, a 200,000 m3 tanker ship has been designed for transporting H2. Also in Japan, an H2-fueled commuter train is in operation, using H2 at 35 mPa (5,000 psig or 350 bar) to fuel a 125 kW ”Forza” proton exchange membrane (PEM) fuel cell by Nuvera (http://www.rtri.or.jp).

Hydrogen buses operate in Montreal and Bavaria, an H2-powered passenger ship sails in Italy, and the 2008 Olympics in Beijing featured hydrogen vehicles. Russia has flown a jet, fueled partly by hydrogen. In the United States, the Defense Advanced Research Project Agency (DARPA), NASA, and the Air Force are jointly developing an Earth-orbit airplane fueled by

H2. Two teams (in Turin and Madrid) are converting two light planes so that they can use hybrid fuel cell–battery electric engines.