Current status of direct heat use of geothermal energy in the world and the background of its recent rapid increase

Abstract

Increase in direct heat use of geothermal energy in the world was investigated based on the papers presented at the past World Geothermal Congresses and others. Direct heat use of geothermal energy has been historically reported almost all over the world and yet its capacity is rapidly increasing in this century. Beside groundsource heat pump, conventional direct use has been drastically increasing in recent years as well. A common leading application of conventional direct use among the countries which show large increase is district heating, supported by policy measures toward sustainable energy supply and carbon free society. On the contrary in Japan, there is no obvious increase of conventional direct use in this century. Importance of renewable heat for the carbon neutral society and sustainable development goals should be more emphasized and use of geothermal heat should increase more decently in Japan.