Review of Sustainable Energies Use in Greenhouses in Greece

Greenhouses consume large amounts of energy compared with other agricultural activities contributing to environmental pollution. However the current advances in sustainable energy technologies allow the use of benign energy sources for heat and power generation in them. Various renewable and high efficiency energy technologies are currently used in Greece or could be used in the near future in them. The technologies are mature, reliable and cost-effective. Among them the direct geothermal energy, solid biomass, solar-PV, waste heat re-use and co-generation of heat and power. Their use in small or larger greenhouses reduces the environmental pollution due to fossil fuels use, lowers the dependence on imported fuels, promote investments and create jobs in the local societies. Currently modern hydroponic greenhouses in northern Greece use co-generation of heat and power systems fuelled with natural gas. Heat is used in the greenhouses and the generated power is fed into the grid. Others utilize direct geothermal fluids for space heating. Solid biomass is also used for heating them. All of them can cover all the heating needs in greenhouses. Industrial rejected heat from lignite fired power plants in northern Greece could be easily used in the future for heating them. At the same time the high solar irradiance allows the use of solar photovoltaic (PV) systems for power generation in them. Further integration of sustainable energies in greenhouses in Greece requires the governmental support both in the form of financial subsidies and in removing the existing barriers preventing their use.