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Oak Ridge National Laboratory Team Design Can Recover Electricity From Waste Heat

Discussion in 'Engineering & Technology News' started by Farjand, May 18, 2011.

  1. Farjand

    Farjand Rookie

    Engineering Discipline:
    Generating energy from waste is an interesting topic for many. It not only promises cleaning of environment from hazardous waste but also ensures a greener supply of energy. The energy can be recovered from such waste by many methods like biogas plants. However, the heat generated due to constant running and functioning of electrical gadgets presents us with a big problem. It seems that the problem is solved to a great extent by Mr. Scott Hunter led Oak Ridge National laboratory (ORNL) research team.


    Every time we switch on an electrical device, a lot of heat energy is generated by electrical components, which is actually a waste of electrical energy. The solution to this is now available. The principal utilizes “pyroelectric materials” for conversion of thermal to electrical energy conversion. The basic structure designed by Scott is of the form of computer chips. The device is composed of cantilever structures of 1mm<sup>2</sup> area each. About 1000 such structures are integrated in an area of 1 inch<sup>2 </sup>array. The ORNL team uses many such array structures together to save a lot of electricity. A single one can produce about 10 milliwatts of electricity. But when many such arrays are combined, the team expects that it can achieve an efficiency of about 10 to 30%. So this means that whenever a device generates heat during its functioning, the heat is again converted back to usable electricity.

    The structure resembles a MEMS pyroelectric capacitor. The property of such a capacitor is that it generates a current in alternate directions when it is cooled or heated. The amount of electricity and efficiency however depends on the temperature of these “micro-electro-mechanical structured” pyroelectric capacitors. Earlier studies have suggested only an efficiency of about 1 to 5%.

    Scott Hunter and his team are enthusiastic of the project. While telling about the actual mechanism he explains that the heat transfer takes place by this cantilever structure effectively which oscillates between hot and a cold surface. The cold surface acts as a heat sink for the hot cantilever tip. The team also focused on how there will be a fast transfer of electricity. The faster the temperature changes, the efficient will be the electricity production.

    Speaking of the commercialization along with technology, Hunter said, “<em>In the US, more than 50 per cent of the energy generated annually from all sources is lost as waste heat, so this actually presents us with a great opportunity to save industry money through increased process efficiencies and reduced fuel costs while reducing greenhouse-gas emissions.</em>” So it seems to be really a profitable deal to invest in this technology.
    The technology is the latest among its kind and not many attempts have been made in this direction. A speedy commercialization of this would be a major contributing factor for achieving green energy not only for US but also for rest of world.

    Source: TheEngineer Image: TimeLordz
  2. I wish my Laptop waste heat can be converted into electricity :)

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