Combined use of geothermal energy in series and parallel

Abstract

The combined use (generation of electricity and district heating) or the direct use (industrial application) of geothermal energy is more efficient from the thermal point of view than that of only generating electricity. Examples of generation of electricity and industrial applications in Iceland such as: fish drying and geochemicals extraction at the Reykjanes peninsula, the power plant at Svartsengi and the diatomite plant at Namafjall. The utilization of geothermal energy for combined use (generation of electricity and drying) both for a production in series and in parallel are analyzed. Two types of rotary dryers, one which is air heated and the other an indirect-heat-rotary-steam-tube dryer are considered for both types of productions and compared. The production in series with the use of a back-pressure turbine and an indirect-heat-rotary-steam-tube dryer is the most advantageous from the total thermal efficiency point of view.