Possibilities of Using Renewable Energy Sources for Covering All the Energy Needs of Hydroponic Greenhouses. A Case Study in Crete, Greece

Hydroponic greenhouses consume large amounts of energy in order to cultivate the desired crops. Usually they consume fossil fuels for heat production and grid electricity for the operation of various electric devices. The aim of the current work is the investigation of the possibility of using renewable energy sources for covering all the energy needs of a hydroponic greenhouse in Crete, Greece. This could be achieved with the combined use of solid biomass and solar electricity. Solid biomass and solar-PV technology are mature, reliable, well-proven and cost-effective technologies. Solar irradiance and solid biomass, in the form of olive kernel wood, are abundant in Crete and they are extensively used for energy generation. For a hydroponic greenhouse in Crete, Greece with a covered area of 1,000 m2 and annual energy consumption of 245.5 KWh/m2, the installation cost of the abovementioned renewable energy systems has been estimated at 42,380€ and the CO2 emissions savings due to the use of solar energy and solid biomass at 104,725 kg CO2 /year. The size of the solar-PV system has been calculated at 17 KWp and the annual consumption of olive kernel wood at 66.87 tons/year. Therefore the use of renewable energies instead of fossil fuels in hydroponic greenhouses results in economic and environmental benefits and it should be promoted in order to increase sustainability in agriculture.