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Chemical Engineering

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Collect more solar energy and waste heat for process water heating

| By Mary Page Bailey

A new technology developed by Enertopia Corp. (Kelowna, B.C., Canada; aims to improve the efficiency of solar panels by collecting excess waste heat and using it to heat water. Besides improving energy output, the technology also significantly lengthens the useful lifespan of solar panels by reducing overheating.

Enertopia’s technology involves outfitting the backside of a solar panel with a sponge-like heat-dissipative device made of ethylene propylene diene monomer (EPDM). “Basically, there’s water flowing underneath the solar panels, which removes the excess heat, but in order to couple the panel to the EPDM rubber device and not shock the panel or break the glass, we have developed a breakthrough technology that actually acts like a one-way heat sink on the back of the panel,” explains Mark Snyder, lead process technologies consultant for Enertopia. In some conditions, says Snyder, the EPDM device can take advantage of dewpoint differences and draw water out of the atmosphere, meaning that it can actually create water in addition to collecting waste heat. “If you have a large array, you could actually be making several thousands of gallons of water per day,” he adds. On either side of an array of panels with the special EPDM medium applied, header lines gather water and pump it through a series of insulated tanks and solar-thermal booster panels made of the same EPDM medium, where the water can be heated as high as 220°F.

Enertopia is currently maturing the technology as part of an effort to create a closed-loop system for solar-powered direct lithium extraction (DLE) technologies, which are currently under review. The solar-absorption circuit provides carbon-neutral heating for process water, which is then used to remove lithium from impurities in a brine solution. The company is currently testing a demonstration system near Sacramento, Calif., that Snyder says has raised the efficiency of the solar panels by 20 to 25%. The company is also working on a 3-MW system to demonstrate the effectiveness of the system for agricultural use.