Scientists in Ghana have developed a device that combines a conventional solar-powered steam cooker with sand-based thermal energy storage. The system can achieve a thermal efficiency of 38.9% and has a payback period of 4.5 years.
A research group from Ghana has developed a solar-powered steam cooker (ISESC) with sand-based thermal energy storage (WKO).
“The potential of sand, given its thermal stability and low cost, has not yet been extensively explored. Existing research mainly uses diodes, resistance heaters or induction systems as heat sources, with limited exploration of direct steam generation using stored heat in the sand,” the academics said. “The integration of steam cooking with sand-based TES into solar electric systems is a new area, and its efficiency in steam production and food cooking remains unclear.”
The tested setup consists of 20 photovoltaic (PV) modules, each with a maximum power of 580 W and an efficiency of 22.65%. The modules are mounted on a ground structure with an inclination angle of 10° facing south and an azimuth angle of 0°. The electricity generated is fed to the thermal energy storage system (TES), which consists of two components: a mild steel sand container filled with quarry sand, in which a DC-resistant heating element is embedded.
A water chamber containing 10 kg of water is installed above the sand layer, which generates steam that heats the food in the cooking space. The cooking chamber is 143 cm high, 150 cm long and 57.5 cm wide, while the dimensions of the thermal battery are 15 cm x 65.5 cm x 44 cm.
The tests were conducted at the Kunst Senior High School in Kumasi, Ghana. From October 21 to 24, 2024, water boiling tests were conducted daily between 10 a.m. and 3 p.m. Cooking tests followed from November 5 to 7, 2024. The instruments used included a solar radiation meter, an infrared temperature gun, a voltmeter, an ammeter and a thermal camera.
The results showed that the cooking chamber reached a temperature of 105–110 C, sufficient to cook 16 kg of rice in 80 minutes, 16 kg of beans in 140 minutes and 32 kg of plantain in 85 minutes. The ISESC achieved a thermal efficiency of 38.9%, exceeding the performance of Scheffler dish solar steam systems (25–26.5%) under similar conditions by approximately 12–14%. The sand-based TES stored 13–15 MJ of energy and provided 4–6 hours of reliable cooking even under variable solar radiation of 400–900 W/m2.
Life cycle cost analysis indicated a payback period of 4.5 years, with total costs over 20 years estimated to be 47% lower than traditional biomass stoves. The ISESC’s annual emissions savings were calculated as 5,312.22 kg CO₂, 11.10 kg NOx and 7.05 kg PM2.5, contributing to reduced deforestation, lower indoor air pollution and support for Ghana’s Nationally Determined Contribution Targets (NDC).
The system was described in “Experimental analysis of an institutional solar steam cooker with sand-based thermal energy storage”, published in Advances in solar energy. Scientists from Ghana’s Kwame Nkrumah University of Science and Technology, Technology Consultancy Center – International Center for Innovation, Manufacturing, Technology Transfer, and Entrepreneurship (TCC-CIMET) and Cape Coast Technical University.
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