Possibilities of Using Industrial Waste Heat for Heating Greenhouses in Northern Greece

The possibility of using the rejected heat from lignite-fired power plants for heating greenhouses in northern Greece has been examined. Although currently industrial waste heat is used for district heating in a few towns in Greece, its use in agriculture has not been reported so far. Due to many environmental and economic benefits symbiosis of industrial and agricultural activities is promoted in many countries. Greenhouses in northern Greece utilize mainly natural gas as heating fuel. However heat recovery from the existing power plants and its use in greenhouses could increase their energy efficiency and reduce the thermal pollution. It will also decrease the use of fossil fuels in greenhouses and the resulting carbon emissions as well. Their heating requirements have been estimated at 170 W/m2 and the required hot water temperatures are 50-60 oC below the required water temperature in district heating systems, at 120 oC. Currently the price of heat sold in the district heating system in the town of Kozani is 0.0435 €/KWh, which is very attractive for heating greenhouses compared with other existing methods or fuels. It has been estimated that the heat recovery from the power plants at 70 MWth could cover the heating needs of 41.2 ha of modern agricultural greenhouses in northern Greece. Recycling of industrial waste heat in greenhouses in northern Greece, apart from the resulting environmental benefits, will offer a competitive advantage, increasing the profitability of those enterprises.