MIT designing solar cells that use heat instead of light

A team of researchers at MIT have come up with a new twist on an old idea – generating electricity from heat.  But instead of using boilers and turbines, they’re using specialized solar cells that use the heat to create infrared light at a specific frequency best suited to the cell.  While thermal photovoltaic (PV) cells have been around for a while, the MIT team took the thermal PV concept and added a nanotech sized layer of tungsten to the front of the cell – when the tungsten is heated, it emits infrared light that is then used by the cell to create electricity. The cell is tuned to be most efficient at the exact wavelength of infrared light that the tungsten emits.

thermal PV system designed by MIT
thermal PV system designed by MIT
The new cells are far more efficient than older thermal PV cells, so much so that MIT feels that they will be able to be used in all sorts of devices to create electricity.  What they’re focusing on now is developing tiny silicon micro-reactors to generate electricity. They’ve made a button sized micro-reactor fueled by butane that runs three times longer than a lithium-ion battery of the same weight. It can be recharged instantly just by adding a tiny cartridge of fresh fuel.  They’ve also come up with another device that’s powered by a radioisotope that slowly produces heat from radioactive decay – it could last 30 years without refueling or servicing.

Looking forward, all sorts of efficiencies are possible.  Since MIT feels that these cells would ultimately be fairly inexpensive (tungsten is a pretty common material), these cells could be used to generate electricity from almost anything that generates heat – a computer, a TV, your clothes dryer, etc).  In other words, you’d be recycling the electricity that right now is wasted as heat back into electricity to power the device.

Nanoscale sized holes used in MIT thermal PV cell
MIT thermal PV cell. Nanoscopice sized holes absorb heat and then radiate wavelenghts that the cell uses to convert into electricity


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