Fuel Cell Technology

Fuel cell technology 1

Running head: FUEL CELL TECHNOLOGY: TRANSPORTATION AND RESIDENTAL/ COMMERICAL APPLICATIONS

Fuel Cell Technology: Transportation and residential/commercial applications

Monique

University

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A fuel cell is an electrochemical energy conversion device. A fuel cell converts the chemicals hydrogen and oxygen into water, and in the process it produces electricity. With a fuel cell, chemicals constantly flow into the cell so it never goes dead as long as there is a flow of chemicals into the cell, the electricity flows out of the cell. Most fuel cells in use today use hydrogen and oxygen as the chemicals. Fuel cell provides a DC (direct current voltage that can be used to power motors, lights or any number of electrical appliances. The fuel cell will compete with many other types of energy conversion devices, including the gas turbine in your city's power plant, the gasoline engine in your car and the battery in your laptop.

Combustion engines like the turbine and the gasoline engine burn fuels and use the pressure created by the expansion of the gases to do mechanical work. Batteries converted chemical energy back into electrical energy when needed. Fuel cells should do both tasks more efficiently. Fuel cells improve battered powered cars and gasoline powered cars more efficiently. Fuel-cell-powered electric cars are powered with pure hydrogen. It has the potential to be up to 80%

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efficient, and with today's gas prices that would be wonderful. The efficiency of a gasoline-powered car is surprisingly low. All of the heat that comes out as exhaust or goes into the radiator is wasted energy.

The engine also uses a lot of energy turning the various pumps, fans and generators that keep it going. So the overall efficiency of an automotive gas engine is about 20%. That is, only about 20% of the thermal-energy content of the gasoline is converted into mechanical work. The efficiency of an electric car is 72% for the car, 40% for the power plant and 90% for charging the car. That gives an overall efficiency of 26%. The overall efficiency varies considerably depending on what sort of power plant is used. If the electricity for the car is generated by a hydroelectric plant for instance, then it is basically free (we didn't burn any fuel to generate it), and the efficiency of the electric car is about 65%.

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Efficiency is not the only consideration, however. People will not drive a car just because it is the most efficient if it makes them change their behavior. They are concerned about many other issues as well. Such as; is the car quick and easy to refuel, can it travel a good distance before refueling, is it as fast as the other cars on the road, and how much pollution does it produce? Fuel-cell-powered cars will start to replace gas- and diesel-engine cars in about 2005. A fuel-cell car will be very similar to an electric car but with a fuel cell and reformer instead of batteries. Most likely, you will fill your fuel-cell car up with methanol, but some companies are working on gasoline reformers. Other companies hope to do away with the reformer completely by designing advanced storage devices for hydrogen.

Fuel cells also make sense for portable electronics like laptop computers, cellular phones or even hearing aids. In these applications, the fuel cell will provide much longer life than a battery would, and you should be able to" recharge" it quickly with a liquid or gaseous fuel. Fuel-cell-powered buses are already running in several cities. The bus was one of the first applications of the fuel cell because initially, fuel cells needed to be quite

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large to produce enough power to drive a vehicle. In the first fuel-cell bus, about one-third of the vehicle was filled with fuel cells and fuel-cell equipment. Now the power density has increased to the point that a bus can run on a much smaller fuel cell. This is a promising application that you may be able to order as soon as 2002. General Electric is going to offer a fuel-cell generator system made by Plug Power. This system will use a natural gas or propane reformer and produce up to seven kilowatts of power (which is enough for most houses). A system like this produces electricity and significant amounts of heat, so it is possible that the system could heat your water and help to heat your house without using any additional energy. Some fuel-cell technologies have the potential to replace conventional combustion power plants.

Large fuel cells will be able to generate electricity more efficiently than today's power plants. The fuel-cell technologies being developed for these power plants will generate electricity directly from hydrogen in the fuel cell, but will also use the heat and water produced in the cell to power steam turbines and generate even more electricity. There are already large portable fuel-cell systems available for providing backup power to hospitals and factories. There are several types of fuel cells. The chart below shows the different types of fuel cells, their operating temperatures, their utility power, their applications, their costs, their size, and the electrical efficiency as pertaining to the device their associated with. You will also note in the chart that fuel cell technology is proficient in residential and commercial buildings, passenger vehicles (not all fuel cell technology will be used in vehicles), and other power applications.

Table 1: Types of Fuel Cells

Proton Exchange Membrane Fuel Cell (PEM) Alkaline Fuel Cell (AFC) Phosphoric Acid Fuel Cell (PAFC) Molten Carbonate Fuel Cell (MCFC) Solid Oxide Fuel Cell (SOFC)

Electrolyte Ion Exchange membrane (solid polymer) Potassium Hydroxide (KOH) Aqueous Phosphoric Acid Molten Carbonates Solid