Oh MIT, we can always count on you to come up with the most clever, little inventions. Just the other day you created goo-powered batteries to replace lithium-ion and now you've gone and found a way to make photovoltaic electricity without sunlight!
Though that's technically not a new idea, the way these whiz kids have engineered the surface of a material to convert heat into precise wavelengths of light most definitely is. These wavelengths are chosen to match those of photovoltaic cells that can best become electricity. The new discovery combines burning butane and nanometer-sized pits to fine-tune those wavelengths. Then they're paired with PV cells that are tuned into those wavelengths to suck out the energy.
Why should we care? The end-product of all this is a generator the size of a dime that can run three times longer than a lithium-ion battery—something those MIT students must really hate. That generator can be recharged immediately by inserting a tiny cartridge of fresh juice. Oh, and they also made a radioisotope that produces heat from radioactive decay. It could quite possibly power its own electricity for 30 years. NBD.
So the former could be used to power, say, a mobile device, and the latter could be used to power say, an entire spacecraft on a long mission. Either way, those blessed MIT geeks have taken one small step for battery power, and one giant leap for all those people out there who can't remember to charge their gadgets.