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Hydrogen power is coming, by way of the fuel cell, an invention that's been around since the sixties and will soon find its way into vehicles. Hydrogen is an odorless, colorless gas, the lightest and simplest of all the elements in the universe. A hydrogen atom has a nucleus containing a single proton that is circled by a single electron. (An atom of uranium has a nucleus with 92 protons and 146 neutrons, surrounded by 7 shells containing 92 electrons.) Hydrogen is also highly volatile and flammable. It has been used to power rocket engines and make devastating bombs. But it is not the combustible nature of hydrogen that the fuel cell harnesses. Rather, it is a basic electrochemical reaction that scientists have understood for more than 150 years! Electricity can be used to split water molecules into their basic components--hydrogen and oxygen. This process of running electricity through a solution to separate materials is called electrolysis. Over 150 years ago, it was demonstrated that if electrolysis was "run in reverse" ... that is, if hydrogen and oxygen were combined to make water ... the process would release electricity! This is what a fuel cell does. The hydrogen fuel is fed into one end of the cell, where it comes in contact with a platinum plate. The platinum acts as a catalyst that helps break down hydrogen atoms into positively charged ions and negatively charged electrons. The electrons are then screened out using a substance called an electrolyte. The ions can pass through it; the electrons cannot. All the electrons are collected and sent through a wire. That stream of electrons is electricity, which can be used to power a motor.  The wire eventually is routed back to the cell, where the electrons, ions and oxygen recombine to make water ... the fuel cell's only waste product! You can safely drink the exhaust! It was not until NASA began searching for onboard power supplies for its Gemini and Apollo spacecraft that hydrogen fuel cells became a true applied technology. In space travel, traditional internal combustion power is not feasible. Fuel cell technology is efficient, the fuel is light and there is no heat or waste gas to deal with. In fact, fuel cell technology is sometimes called "cold combustion." By 1965 fuel cells were standard equipment on spacecraft. Standard, but not cheap. The NASA cells used not only platinum, but an expensive metal called niobium plated with gold, and a special electrolyte. A host of expensive materials are still required to manufacture the cells, but the costs are slowly going down. For example, the amount of platinum needed for a fuel cell large enough to power an auto has been dramatically reduced, dropping costs from $30,000 to $500. In place of gold-plated niobium, a carbon graphite material is used instead. The electrolyte, however, still remains a problem.The electrolyte still costs about $80 a square foot. It needs to be down at $5 to $10 to be economical. The weight of the cells is another problem. An internal combustion engine weighs about two to four pounds for every kilowatt of power it generates. Fuel cells weigh 15 to 30 pounds per kilowatt. But some of the weight problem is offset by the fact that the cells are more efficient than normal auto engines. Still, problems of size, weight and power are all ones that will eventually be solved. There is already a hydrogen-powered passenger bus slated for test marketing in Chicago and Vancouver, British Columbia.  The fuel cells fit into the space that normally holds the bus' diesel motor. The price of the bus, however, is $1.1 million ... four times the cost of a standard diesel bus. But with mass production of the bus and fuel cells, the price could drop to about $300,000. Next summer, Chicago will have at least three of these buses on the city streets as part of a three-year pilot project. The 40-foot-long coaches look like your average bus, carry about 40 passengers, and travel at average speeds. There just won't be any of the soot, smell or noise of a diesel bus! Besides that, since the hydrogen bus has no mechanical parts, such as a transmission, needs no lubricating oils and does not operate at high temperatures, maintenance should be much easier. Of course, hydrogen-powered vehicles will need hydrogen. That is another problem. Most commercial hydrogen is made as part of the processing of natural gas. As a fuel it is about 20 percent more expensive than a comparable amount of gasoline. You need about 15 pounds of hydrogen to go 300 miles. That doesn't sound like much, but hydrogen is very light, and takes a very big tank! Gaseous hydrogen could be pumped into a vehicle's tank in five minutes using compressors, according to studies. Another problem with hydrogen is that since it is such a simple molecule it can easily leak through cracks and seals. There may be a safety risk. But we use gasoline in our cars and natural gas in our kitchens. The key wil be to design safe systems to handle the hydrogen. Hydrogen can also come in liquid and solid forms, that require less space, and do not leak as readily, but each has drawbacks in the ease of handling and cost of refueling. |
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