Thermal energy production from low temperature geothermal brine - technological aspects and energy efficiency

Abstract

A short description of the West Lithuanian geothermal anomaly is presented in this report. The significant fluctuation of geothermal reservoir characteristics, high salinity and relatively low temperatures cause each case of geothermal utilization in Lithuania to be considered in detail and be well-grounded. Literature review of geothermal heating systems, exploiting low temperature geothermal fluids was made highlighting the main technological aspects and problems which can arise during utilization of geothermal brines. Experience of geothermal utilization, obtained in other countries, should be used to substantiate technological schemes of geothermal plants in Lithuania. A computer programme based on a simplified geothermal reservoir model, well construction and geothermal plant scheme has been developed for calculations of geothermal energy production and energy consumption in the main technological equipments. Coefficient of energy performance and gained thermal energy are suggested to estimate thermal energy generation efficiency. The tentative cost of the main equipment has been collected. This data should be the basis for further development with the aim to prepare a method for the consideration of geothermal utilization projects. Preliminary estimation of efficiency of thermal energy production for existing district heating systems from the West Lithuanian geothermal brines have been made, using computer calculations. The characteristics of geothermal reservoirs and the main technical parameters of a geothermal plant have been examined.