Scientists Use “Solar Steam” to Sterilize Medical Equipment, Human Waste

Rice University graduate student Oara Neumann, left, and scientist Naomi Halas are co-authors of a new study about
 a highly efficient method of turning sunlight into heat

Modern medical techniques, specifically stringent sterilization practices, have led to a dramatic drop in the number of post-op infections—assuming the facility has the necessary electricity and equipment to do so. However, in the remote regions of developing countries like India, neither of those is guaranteed. But that's where Rice University's new solar steamer comes in. This ingenious device cheaply and easily captures the Sun's rays to sterilize anything from scalpels to human excrement. Huzzah, no more infections from backwoods surgeries! And—bonus—your shit no longer stinks.

Developed at Rice University’s Laboratory for Nanophotonics (LANP), the Solar Autoclave machine uses nanoshells (small spherical nanoparticles with a dielectric core and metal skin) to convert both visible and invisible spectrums of light directly into heat—as much as 80 percent of the incoming energy. Overall the system has an efficiency of just 24 percent but that's still way better than the 15 percent efficiency of other solar technologies. And when submerged in water, they cause water to vaporize on contact generating enough steam and pressure to kill bacteria, molds, and virii.

The machine uses a parabolic mirror to capture the sunlight and concentrate the beam on a clear chamber containing the nanoparticles (the black sludge in the bottom) submerged in impure water. As the light shines on the chamber, the nanoshells absorb the energy, convert it to heat, and cause the water to spontaneously vaporize. The resulting steam can then be drawn off to either sterilize surgical equipment or condensed back in pure, potable water.