Abstract

The possibility of using fuel cells powered by solar hydrogen for energy generation in greenhouses with reference to the island of Crete, Greece has been examined. Change of fossil fuels used in greenhouses with renewable energies and sustainable energy technologies is very important for mitigation of climate change. Various renewable energy sources and low carbon emission technologies including geothermal energy, biomass, solar photovoltaics and co-generation systems have been used so far. Use of solar photovoltaics for generating electricity consumed in water electrolysis for hydrogen production has been investigated. Hydrogen feeding a proton exchange membrane fuel cell co-generating electricity and heat was used in a greenhouse located in Crete, Greece. The system could be useful in a stand-alone greenhouse with annual specific energy consumption at 150 KWh/m². A solar photovoltaic system with nominal power at 33.33 KW_p powering an electrolytic cell at 5.71 KW could produce annually 2,083 kg hydrogen. The hydrogen could feed a fuel cell at 1.71 KW_el generating annually all the electricity required in a greenhouse of 1,000 m². Co-produced heat could also cover 11.11% of the annual heat requirements in the greenhouse. It was found though that the overall electric efficiency of the system was very low at 4.5%. The low overall efficiency and the size of the solar-PV required indicate that the abovementioned energy system is not suitable in commercial agricultural greenhouses.

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