Tech Directions- October 2008

number of new cars on the road. Each can generate electricity for powering its lights, accessories, and air conditioner. In fact, if you add up the electric generation potential of all these new cars, it turns out to be more than the total power generation of all the large electric generating stations in the country! Why don’t we just hook all those cars up and get our electricity that way? Could I plug my car into my house and get my electricity? Yes, you could, but it is not easy nor safe to do that today. Our cars were not designed to work that way. They do not have convenient electrical connections to make it possible, and today’s cars are too dirty to run them all day. In short, it does not make economic or practical sense to use our existing cars this way. However, in the future when we have fuel cell-powered cars, they will be clean and designed to run all day; and they will change everything we know about the car. It is best to think of a fuel cell as a continuous battery that will constantly supply electricity as long as the proper chemical fuel is supplied to it. In this case, a fuel cell simply needs a source of hydrogen and oxygen to work. The hydrogen can be obtained from a hydrocarbon fuel like natural gas, and we can take the oxygen right from the air. Like a battery, a fuel cell operates on the principles of electrochemistry (oxidation-reduction). Unlike a battery, it does not depend on a ﬁxed amount of stored chemicals. Note that fuel cells were used to power our nation’s spacecraft to the moon. They provided all the electricity and fresh water onboard the space vehicles. Using a hydrocarbon fuel as the hydrogen source, when hydrogen and oxygen combine, all that is created is carbon dioxide (like what we exhale) and water, plus some heat. That’s it. Using fuel cells in our cars would be a huge beneﬁt for reducing air pollution, and doing so would help us reduce our dependence on foreign oil. will be available, and that we can make them connect to our homes and anywhere we park our cars. We could use them to generate electricity and use it directly or sell it back to the local utility. How about some math here? First, a fuel cell needed to power a car would be about 40-60 kW in size. Already you can see that this is considerably larger than what your house typically needs, on average about 15 times larger. Certainly, it would be possible to use your car to power your house whenever it is parked at home in the garage, and you could also sell back quite a bit of power to the utility for its other customers. Assume you live in a small suburban community with 4,000 residents and that each family has four members. That means 1,000 homes, and each home has two cars, so this little community has 2,000 cars. Now if each car can generate 40kW of power, those 2,000 cars would be able to generate a total of 80,000 kW, or 80 megawatts (80 MW). If each house in your town needed, say, 4 kW of power, all 1,000 of them would need a total of 4,000 kW, or 4 MW of power. Subtracting this from the 80 MW of power the cars could generate leaves a surplus of 76 MW to be sold back to the local utility. Since your local utility usually builds power substations in the range of 20-60 MW in size—that 76 MW of surplus power is larger than the utility’s biggest substation. Fuel cell-powered cars in your town alone could generate enough power for many towns like yours! The point of these calculations is to show that small amounts of power generation from many fuel cell-powered cars could add up quickly into very serious numbers (just like the peak electric load from all those window air conditioners on a hot, humid day). And the impact of fuel cell-powered cars will extend far beyond your house. Looking at the Larger Picture What might happen if you drive your fuel cell-powered car to a park- Putting Fuel Cells to Work Assume that some time in the near future, fuel cell-powered cars www.techdirections.com POWER & ENERGY 17 http://www.g-w.com http://www.g-w.com http://www.techdirections.com

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Tech Directions Technically Speaking Contents Direct from Washington The Report Technology's Past Technology Today Mastering Computers Automotive Power and Energy Technology Education Career Directions Electronics Special Feature More than fun

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