A group of scientists from Israel’s Ben-Gurion University of the Negev is proposing to cool down PV modules mounted in solar arrays located at large receiving gas terminals around the world with the cold temperatures leftover during the regasification process of liquefied natural gas (LNG). Regasification is the process of returning LNG to its gaseous state at a temperature of -162 degrees Celsius.
The proposed approach, which the researchers themselves define as “unorthodox,” consists of using part of the LNG that arrives at the terminal for cooling the PV plant’s modules, before it goes into heat exchange with seawater for regasification. “The fraction of the LNG diverted to the PV system for partial regasification will depend on ambient conditions, solar irradiance, PV efficiency and economic factors,” the group specified.
The academics conducted tests on small solar cells with 17% efficiency and an active area of 0.45 cm2. The cells were tested for cooling with LNG in a cryostat (Oxford Instruments MicrostatN with a MercuryiTC controller). This is a multi-channel controller and superconducting magnet for low-temperature research and cryogenics – the study of the production and behavior of materials at very low temperatures. “Because the cells resided in the evacuated chamber of the cryostat, no frost formation occurred,” they specified.
The cells received irradiance levels of 0.3, 0.5 and 1 kW/m2 through a global standard spectrum (AM1.5g) solar simulator. “There were no perceptible changes in cell behavior at any irradiance or temperature as a consequence of the extreme temperature cycling,” the team stated.
The experiment showed, according to the scientists, that the cooling with the LNG may boost efficiency of the PV modules “by close to 80% relative.”
A major challenge for the application of this technology to real projects, however, remains the risk of frost formation on the PV panels, the group warned. “Creating an evacuated space between the irradiated side of the PV panels and a transparent glazing above them would mitigate the problem,” the stated. “However, the incremental cost for large cost-effective commercial installations may be unacceptable.”
They suggested the potential use of new generations of non-expensive super-hydrophobic materials that could be applied to the PV panels, as well as the utilization of future low-cost mechanical solutions tailored to such systems as a solution. They also pointed out the heat exchange hardware that should be bonded to the back of each PV module, and the piping through the PV field, as another potential challenge in terms of costs and deployment.
“The workability of such systems is strengthened by the fact that both the PV systems and the LNG regasification systems are, separately, mature, economical technologies, the integration of which would also entail the use of existing mass-produced components,” the Israeli group concluded.
The findings of the research were presented in the paper Boosting silicon photovoltaic efficiency from regasification of liquefied natural gas, published in Energy.
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