Production and utilization of high-temperature geothermal energy – statistical data processing methodology

Abstract

Geothermal resources can be found on the earth in different forms and chemical/physical characteristics. From the viewpoint of immediate energetic utilization, they are usually classified in low- or high-temperature systems. At present only the high temperature systems are considered economically viable on an industrial scale for the production of electricity.

In this framework high temperature geothermal production in Italy is monitored monthly, quarterly and annually, recording thermodynamic properties of geothermal fluid in different sections of steam pipeline from head of wells to power generating turbines (flow rate, pressure, temperature, salt content, etc.).

In the Italian energy balance, the contribution of geothermal resources to electricity generation is evaluated on the basis of the real average heat content, expressed in calorific terms, of the geothermal fluid required to generate 1 kWh of electricity.

In Italy two further alternative evaluation criteria have been introduced. The first (substitution criterion) is based on the quantity of primary fuel that would be consumed in conventional thermal power stations (primary equivalent of kWh) to produce the same quantity of electricity. The second (final energy criterion) evaluates the real energetic content delivered to final consumers. The two criteria are adopted by the major international institutions that publish energy statistics (OECD, IEA, EEC).