MIT Scientists Use a Sponge to Turn Sunlight Into Steam Energy

Nearly all utility plants generate electricity with steam. Whether it’s a coal plant or a nuclear plant or a solar thermal plant, all of these facilities use fuel to heat water to create steam that turns a turbine that generates electricity.
Now researchers at MIT have developed a completely new structure for turning sunlight into steam: a sponge. The advance could one day lead to an efficient, inexpensive and emission-free way for creating steam that could be used to not only generate steam for energy but also for desalination and sterilization.

This sponge, developed by Gang Chen, head of MIT’s Mechanical Engineering Department, post-doc Hadi Ghasemi and their colleages, is comprised of a layer of graphite flakes on top of a carbon foam that float on layers of liquid, including water. When sunlight hits the surface, it produces a hotspot in the graphite that pulls water up through the porous material. Heated, the rising water evaporates as steam.
So far, the material has been able to convert 85% of sunlight into steam. What’s more, very little heat is lost or wasted in the process.
Current solar-thermal plants that concentrate sunlight in order to heat fluids that produce steam require energy about 1,000 times that of an average sunny day. But the MIT approach produces steam with a solar intensity of only 10 times that of a sunny day.
This means that the cost of the infrastructure and energy required to generate steam could be much lower than conventional methods.
“This is a huge advantage in cost-reduction,” Ghasemi told MIT News. “That’s exciting for us because we’ve come up with a new approach to solar steam generation.”
Achieving that end is the team’s next step.
“Our system is not pressurized currently, and we plan to explore that direction,” Chen told DNEWS in an email.