Gudni Axelsson’s paper: “Sustainable geothermal utilization- Case histories; definitions; research issues and modeling” was one of two papers selected to receive the IGA Best Paper Award for 2014.  This wide-ranging paper introduced the 2010 Geothermics Special Issue (Vol. 39, No.4): Sustainable Utilization of Geothermal Energy, for which Gudni and Mike Mongillo were Guest Editors.  You may access the abstract of Gudni’s paper at:; and the table of contents for the entire Sustainability Special Issue at:

The IGA commented that: Sustainability is a key issue in judging the potential contribution of geothermal resources to mitigation of climate change. This paper provides definition of sustainable production of geothermal fields and theoretical analysis that is supported by numerical modeling of different types of geothermal fields from various geological settings around the world. The paper identifies the research issues in understanding sustainability of geothermal fields. It suggests that thermal balance of a production field can be achieved at the 100-300 year time scale. It also demonstrates through modeling that the effect of heavy abstraction is often reversible on a time-scale comparable to the period of utilization.