If we know the amount of heat required. Canwe convert it into elcetrcity
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Energy is one of those big problems; in the United States, more than half of the energy we burn each year gets lost as heat instead of being put to use.
"We do all this work to get oil out of the ground and to refine it, but when we try to do some work with it, most of the energy goes out the exhaust pipe of a car or out the smokestack of a power plant," White says. "Even if we could reclaim a small fraction of what we throw away as heat, that would have a significant impact on our energy use."
There are ways to turn heat into electricity. If a material is hot on one side and cold on the other, the flow of heat from hot to cold can be turned into electricity. But most of the thermoelectric materials on the market today are not very good at doing that. The tricky part, White says, is getting the heat to flow through the material on the backs of electrons. In most materials, the heat flows in a wave that simply makes the material's atoms vibrate faster. That's not a useful phenomenon, and it ends up destroying the important hot-cold differential. In many materials, the vibration of atoms carries away 90 percent of the heat before it can be harnessed.
White's goal is to create materials where the vibrational effects are minimized—or, in other words, where a larger percentage of the heat gets shuttled by electrons, creating a flow of electricity. He also thinks it's important to make sure those materials are abundant and nontoxic.
White may have found a candidate in zinc oxide, a substance used in many brands of sunblock. Zinc oxide is abundant, cheap and safe, and it happens to be really good at moving electrons around. Unfortunately, in its normal state, zinc oxide has a molecular structure that transports heat by vibrating atoms instead of turning it into electricity.
By manipulating zinc oxide at the molecular level, White and his colleagues are able to make it better at generating electricity. First, they stretch the material into wires that measure 50 nanometers across. (That's roughly 10,000 times thinner than a human hair.) That incredible thinness changes the way heat spreads through the material. Next, they embed the nanowires in a silica aerogel, a substance that's terrible at conducting heat. Because of the interesting and unique interactions that occur at very small scales, nanowires can take on the properties of surrounding materials. In this case, the wires became very poor heat conductors. Their ability to conduct heat through atomic vibrations decreased by a factor of 10, so their efficiency in turning heat to electricity shot up. The results were published in April 2013 in Applied Physics Letters, the top journal in the field.
"We do all this work to get oil out of the ground and to refine it, but when we try to do some work with it, most of the energy goes out the exhaust pipe of a car or out the smokestack of a power plant," White says. "Even if we could reclaim a small fraction of what we throw away as heat, that would have a significant impact on our energy use."
There are ways to turn heat into electricity. If a material is hot on one side and cold on the other, the flow of heat from hot to cold can be turned into electricity. But most of the thermoelectric materials on the market today are not very good at doing that. The tricky part, White says, is getting the heat to flow through the material on the backs of electrons. In most materials, the heat flows in a wave that simply makes the material's atoms vibrate faster. That's not a useful phenomenon, and it ends up destroying the important hot-cold differential. In many materials, the vibration of atoms carries away 90 percent of the heat before it can be harnessed.
White's goal is to create materials where the vibrational effects are minimized—or, in other words, where a larger percentage of the heat gets shuttled by electrons, creating a flow of electricity. He also thinks it's important to make sure those materials are abundant and nontoxic.
White may have found a candidate in zinc oxide, a substance used in many brands of sunblock. Zinc oxide is abundant, cheap and safe, and it happens to be really good at moving electrons around. Unfortunately, in its normal state, zinc oxide has a molecular structure that transports heat by vibrating atoms instead of turning it into electricity.
By manipulating zinc oxide at the molecular level, White and his colleagues are able to make it better at generating electricity. First, they stretch the material into wires that measure 50 nanometers across. (That's roughly 10,000 times thinner than a human hair.) That incredible thinness changes the way heat spreads through the material. Next, they embed the nanowires in a silica aerogel, a substance that's terrible at conducting heat. Because of the interesting and unique interactions that occur at very small scales, nanowires can take on the properties of surrounding materials. In this case, the wires became very poor heat conductors. Their ability to conduct heat through atomic vibrations decreased by a factor of 10, so their efficiency in turning heat to electricity shot up. The results were published in April 2013 in Applied Physics Letters, the top journal in the field.
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