Greek Experience with Geothermal Energy Use in Agriculture and Food Processing Industry

Abstract

Greece holds a prominent place in Europe regarding the existence of promising geothermal resources, which can be economically exploited. There is no any electrical use in the country, despite the proven high-enthalpy geothermal potential in the Aegean volcanic arc. At the spring of 2008 the total installed geothermal capacity of direct uses in Greece accounted for more than 120 MWt. The main direct uses until about 2005, such as heating (district, space, greenhouse, soil), balneotherapy, and aquaculture, show practically no progress since 2005. On the other hand, the geothermal heat pump systems showed rapid expansion recently, contributing significantly in the total installed capacity. The covered area of geothermal greenhouses in the whole country remains rather constant since 1995 at about 18-20 ha. Off-season asparagus cultivation has been practiced with success in Greece during the past 12 years with a total cultivated area of about 21 ha. A similar soil system can be used for lettuce early cultivation. An interesting development in recent years is the use of an open-loop geothermal heat pump system for soil warming. Finally, a tomato dehydration unit has been operating since 2001 and during the eight years of its operation it produced almost 70 tn of high-quality dried tomatoes. An analytical recording of the agricultural uses in Greece is presented, and the technical problems pertinent to these applications are also discussed.