Clean Way to Convert Sunlight to Heat

Monday, November 17, 2014 @ 12:11 PM gHale


The “black hole of sunlight” is a new nanoparticle-based material that absorbs and converts more than 90 percent of captured sunlight to heat, researchers said.

The new material can withstand temperatures greater than 700°C and survive for years outdoors in spite of exposure to air and humidity, said an engineering team at the University of California, San Diego. In comparison, current solar absorber material functions at lower temperatures and workers need to overhaul it almost every year for high temperature operations.

RELATED STORIES
Microgrids: Breaking Away from Main Grid
Fuel Cell Works at Room Temperature
Biodiesel Fuels Cross Country Trip
Enhancing Rechargeable Batteries

“We wanted to create a material that absorbs sunlight that doesn’t let any of it escape. We want the black hole of sunlight,” said Sungho Jin, a professor in the department of Mechanical and Aerospace Engineering at UC San Diego Jacobs School of Engineering.

Jin, along with professor Zhaowei Liu of the department of Electrical and Computer Engineering, and Mechanical Engineering professor Renkun Chen, developed the silicon boride-coated nanoshell material. The group’s work ended up funded by the U.S. Department of Energy’s SunShot program.

The novel material features a “multi-scale” surface created by using particles of many sizes ranging from 10nm to 10µm. The multi-scale structures can trap and absorb light, which contributes to the material’s high efficiency when operated at higher temperatures.

Concentrating solar power (CSP) is an emerging alternative clean energy market that produces approximately 3.5GW worth of power at power plants around the globe — enough to power more than 2 million homes, with additional construction in progress to provide as much as 20GW of power in coming years.

One of the technology’s attractions is that it can see action in retrofitting existing power plants that use coal or fossil fuels because it uses the same process to generate electricity from steam.

Traditional power plants burn coal or fossil fuels to create heat that evaporates water into steam. The steam turns a giant turbine that generates electricity from spinning magnets and conductor wire coils.

CSP power plants create the steam needed to turn the turbine by using sunlight to heat molten salt. The molten salt can also end up stored in thermal storage tanks overnight where it can continue to generate steam and electricity, 24 hours a day if desired, a significant advantage over photovoltaic systems that stop producing energy when the sun goes down.

One of the most common types of CSP systems uses more than 100,000 reflective mirrors to aim sunlight at a tower spray painted with a light absorbing black paint material. The material should maximize sunlight absorption and minimize the loss of light that would naturally emit from the surface in the form of infrared radiation.



Leave a Reply

You must be logged in to post a comment.