Evaluation of alternative scenarios to cover the heating needs of a greenhouse
A lot of efforts have been noticed nowadays trying to replace the conventional fuels with alternative ones for two reasons: a. the continuously increasing prices of the fossil fuels and b. the environmental distress due to the polluting gases emitted by them. Renewable energy sources appear to be a reliable solution for covering the heating needs of greenhouse cultivations, since it is believed that they are environmentally acceptable and economically profitable. In the present research work a heating pump system with coefficient of performance (COP) 4:1 is used for heating a 4,800 m2 arch type multi-span polyethylene greenhouse. This heating pump is assumed to be powered by an alternative energy source such as PV panels or the grid. This investigation tries to compare the aforementioned energy systems in terms of energy, economic and environmental performance. The thermal power required for heating the greenhouse was found equal to 846 kW, when the difference between the inside and the outside temperature is DΤ=15°C. The thermal energy demand to heat this greenhouse from December to March, in the area of Thessaloniki, Greece, was calculated to be 508 MWh. Therefore, the conventional fuel in terms of burning oil to cover that energy need was about 40 t. The replacement of such a conventional heating system by heating pumps prerequisite an energy input of 127 MWh considering its COP. Furthermore, a renewable energy source to be used for powering the heating has the advantage to be an environmentally clean system, because no CO2 or other polluting greenhouse gas is emitted. Finally, this proposed system is also economical, since it requires one fourth of the energy demand for heating.
Firfiris, V., Martzopoulou, A., Moutsiou, A. and Ntinas, G.K. 2017. Evaluation of alternative scenarios to cover the heating needs of a greenhouse. Acta Hort. (ISHS) 1170:493-500
heat pump, COP, alternative energy sources, PV panels, grid