Techy Tuesday - Steam from Sunlight

Power Electronics reports on a development at MIT of a way to capture sunlight and create steam at high levels of efficiency.

A new material structure developed at MIT generates steam by soaking up the sun. The structure — a layer of graphite flakes and an underlying carbon foam — is a porous, insulating material structure that floats on water. When sunlight hits the structure’s surface, it creates a hotspot in the graphite, drawing water up through the material’s pores, where it evaporates as steam. The brighter the light, the more steam is generated.

The new material is able to convert 85 percent of incoming solar energy into steam — a significant improvement over recent approaches to solar-powered steam generation. What’s more, the setup loses very little heat in the process, and can produce steam at relatively low solar intensity.

Steam, of course, is useful for sterilization, desalinization, and cleaning.  Most current systems for solar steam generation are huge, with lots of mirrors or lenses collecting the energy concentrating the solar input up to 1000 times.  This system requires much less of that. 

By contrast, the MIT approach generates steam at a solar intensity about 10 times that of a sunny day — the lowest optical concentration reported thus far. The implication, the researchers say, is that steam-generating applications can function with lower sunlight concentration and less-expensive tracking systems. 

This is preliminary and hasn't been scaled up to full production, but it's something to keep an eye out for.  The obvious advantages for sterilizing water in places with too much wildlife in their water supply are just one use.  Don't neglect sterilizing surgical instruments for field or bush hospitals.