Abstract. The classification of geothermal resources is dependent on the estimate of their corresponding geothermal potential, so adopting a common assessment methodology would greatly benefit operators, investors, government regulators and consumers.

Several geothermal classification schemes have been proposed, but, to date, no universally recognised standard exists. This is due to the difficulty in standardising fundamentally different geothermal source and product types. The situation is not helped by the accepted use of inconsistent jargon among the geothermal community. In fact, the term "geothermal potential" is often interpreted differently by different geothermal practitioners.

This paper highlights the importance of integrating the classification of geothermal potential with that of geothermal energy extraction from well-defined development projects. A structured progression, from estimates of in situ quantities for a given prospect to actual production, is needed. Employing a unique, unambiguous framework would ensure that the same resource cannot exist simultaneously under different levels of maturity of the estimate (as in double bookings of resources), which would let stakeholders better assess the level of risk involved and the steps needed for a geothermal potential to achieve commercial extraction.