Engineers from the University of Houston have developed a new device that can both capture and store solar energy. This device promises application in a wide range of areas where solar energy can be used, including power generation, desalination, and distillation.
In contrast to solar panels and solar cells, which depend on photovoltaic technology for the direct generation of electricity, the hybrid device captures heat energy from the sun and stores it as thermal energy. Though photovoltaic solar modules have become progressively economical, they can only provide power when the sun is shining. During cloudy days photovoltaic technology can produce less to zero electricity.
According to the paper published in Joule, it describes the work, combines molecular energy storage and latent heat storage to produce an integrated harvesting and storage device for potential 24/7 operation. The researchers report a storing efficiency of 73% at small-scale operations and as high as 90% at large-scale operations.
In the research conducted by the engineers, up to 80% of harvested energy was recovered at night time, and the researchers said daytime recovery percentage was even higher.
“The high efficiency harvest is due, in part, to the ability of the device to capture the full spectrum of sunlight, harvesting it for immediate use and converting the excess into molecular energy storage”, said Hadi Ghasemi, Bill D. Cook Associate Professor of Mechanical Engineering at UH and a corresponding author for the paper
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The device was developed using norbornadiene-quadricyclane as the molecular storage phase-changing material, an organic compound that the researchers said exhibits high specific energy and remarkable heat release while remaining steady over extended storage times. Ghasemi further said the same perception could be applied using dissimilar materials, allowing performance, including operating temperatures and efficiency to be optimized.
According to professor of chemistry Mr. T. Randall Lee, Cullen Distinguished University Chair and a corresponding author said the device offers enhanced efficiency in several ways: The solar energy is harvested in molecular form rather than as heat, which dissipates over course of time, and the integrated system also decreases associated thermal losses because there is no need to transport the stored energy over piping lines.
“During the day, the solar thermal energy can be harvested at temperatures as high as 120 degrees centigrade (about 248 Fahrenheit),” said Lee, who also is a principle investigator for the Texas Center for Superconductivity at UH
“At night, when there is low or no solar irradiation, the stored energy is harvested by the molecular storage material, which can convert it from a lower energy molecule to a higher energy molecule.”
That allows the stored energy to produce thermal energy at a higher temperature at night than during the daytime, increasing the amount of energy obtainable even when the sun is not shining, he added further.
In addition to Mr. Lee and Mr. Ghasemi, a number of researchers have participated in the work which includes: Varun Kashyap, Siwakorn Sakunkaewkasem, Parham Jafari, Masoumeh Nazari, Bahareh Eslami, Sina Nazifi, Peyman Irajizad, and Maria D. Marquez, all with UH.