Researchers at Columbia Engineering, along with colleagues at the Department of Chemistry at Columbia University, and Stanford University have developed a new, scalable, and low-cost “dip and dry” method for fabricating a solar absorber (SSA) that can harness and convert sunlight to heat for use in a wide range of energy-related applications, from heating water and generating steam to residential heating.
The team, led by Yuan Yang, explained the methods used in a paper published in the August 28, 2017, issue of Advanced Materials.
Harvesting sunlight for renewable energy has been a primary objective for scientists in recent years. Solar-thermal converters, which can absorb light across the entire solar spectrum and convert it to heat at remarkably high efficiencies, offer a highly promising pathway for solar-energy harvesting. However, attaining high-efficiency solar-thermal conversion at low cost remains a challenge.
Working with instruments and facilities in Columbia Engineering laboratory space and the Columbia Nano Initiative (CNI), the researchers were able to fabricate metal-based plasmonic SSAs using an inexpensive process that can tune the SSAs to suit different operating conditions.
An article on the Columbia Engineering website quotes Jyotirmoy Mandal, lead author of the study and a doctoral student in Yuan Yang’s group, saying, “The beauty of the process is that it can be done very simply. We only needed strips of metals, scissors – to cut the strips to size – a salt solution in a beaker, and a stopwatch to time the dipping process.”
With its wide angle, the SSA addressed another long-standing problem faced by solar-absorbing surfaces: the ability to absorb sunlight throughout the day from sunrise to sunset. In tests, the resulting SSAs showed a significantly higher solar absorption at all angles (~97% absorption when the sun is above, ~80% when near the horizon) than existing designs.
”This is a promising instance of how novel optical surfaces for energy-related applications can be developed relatively simply, cheaply, and sustainably,” said Yuan Yang. “Easy-to-manufacture solar absorbers could play an important role in bringing about a renewable energy future.”
The study is titled “Scalable, ‘Dip-and-dry’ Fabrication of a Wide-Angle Plasmonic Selective Absorber for High-efficiency Solar-thermal Energy Conversion.”