Really, What Is That Geothermal Energy?

Abstract

'There is no internationally accepted definition for geothermal energy.’ – could be read still a year ago on the former website of the IGA that was followed by the remark: ‘This is rather unfortunate.’ I agree. The current IGA website speaks only about geothermal, without energy, saying that it is the natural heat of the Earth. This seems to be all right but the upper part of the Earth, i.e. close the surface is usually cold or cool in terms of the temperature, which humans would never call hot, so using the word ‘heat’ is a bit strange. GRC shares on its webpage similar description for geothermal namely ‘Geothermal Energy is heat (thermal) derived from the earth (geo)’. According to the legislation in force in Europe ‘Geothermal energy is the energy stored in form of heat below the earth’s surface.’ that immediately raises the question how a type of energy, which is ‘stored’ only, can be renewable. After having been puzzled by all this confusion the author attempts to propose an alternative definition of geothermal energy based on the conception of internal energy.