Recent Advances of the Basic Concepts in Geothermal Turbines of Low and High Enthalpy

Abstract

A few numbers of countries in the world are involved in geothermal exploration and geothermal development projects. In order to provide a stable power supply without increasing carbon dioxide on global environment problem, a basic condition need to be fulfilled. This condition is high reliability and high maintainability for the geothermal energetic pumps and turbines. Effective efficiency improvement and geothermal turbines system upgrading are very important and also fundamental economical factor. This means that CO2 emissions into the atmosphere are minimal and a higher reliance on geothermal power generation would work on preventing global warming.The solution to climate changes threat is based now, mainly, on renewable and ecological sources of energy. Geothermal energy has the potential to play a significant role in moving the Europe and other regions of the world toward a cleaner and more sustainable energy system. In order to increase the reliability of geothermal steam turbines, assessing the materials life under geothermal environment condition will be an important step. The corrosion process in the geothermal turbine and pumps depends on temperature, pressure, chemistry, mechanical and vaporous carryover of impurities and water treatment (distribution between the vapors, the surface film and rotor blades material, heat transfer properties etc).The aim of this paper is to present a new coating method for geothermal turbines and pumps components using multi composite technology in order to obtain a protective layer to reduce corrosion damages. The results were very promising and the technique used, plasma jet spraying is a very good method to be used on the geothermal turbines and pumps components.

Ground Thermal Diffusivity Calculation by Direct Soil Temperature Measurement. Application to very Low Enthalpy Geothermal Energy Systems

“…From there the underground temperature increases about 3 °C per 100 m depth, due to the internal thermal energy of the Earth. On average, the underground temperature at 10 m depth remains constant throughout the year and substantially equal to the average temperature of the place [ 1 , 2 , 3 , 4 ].…”

“…Geothermal energy is called very low enthalpy (very low enthalpy geothermal energy, VLEGE) when the heat transfer from the ground occurs at low depth and low temperature (usually less than 40 °C) [ 1 ]. To exploit effectively the heat capacity of the ground, a heat-exchanger system has to be constructed [ 5 ].…”

Monitoring the Vertical Distribution of Rainfall‐Induced Strain Changes in a Landslide Measured by Distributed Fiber Optic Sensing With Rayleigh Backscattering

“…On the other hand, it is commonly understood in geothermal energy research that annual soil temperature fluctuates up to 10 m BGL because of ground heat supplied by the sun and rain, although it varies with soil composition and other environmental conditions (Márquez et al, ). On average, the underground temperature at 10 m BGL remains constant throughout the year and is substantially equal to the average temperature of the place (Buzăianu et al, ; Graf et al, ). Based on these studies, we considered that the long‐term temperature changes up to 10 m BGL might affect frequency shift in this study rather than short‐term changes caused by temporal rainfall or sunlight (the thermal conductivities and volumetric heat capacities of rocks related to ground thermal diffusivity do not allow sharp changes in deeper rock/soil temperatures).…”

Dimensionado de intercambiadores de calor horizontales enterrados para instalaciones de energía geotérmica de muy baja entalpía. Un caso práctico

“…Una instalación de VLEGE es aquella que intercambia este calor con el terreno para ser aprovechado, generalmente para climatización, pues la temperatura de intercambio es de tan solo unas pocas decenas de grados. Se demuestra que conforme se va profundizando desde la superficie, la temperatura del suelo se va aproximando a la temperatura media ambiente del lugar (Andújar et al, 2016), de modo que aproximadamente a partir de 10 m de profundidad y hasta 30 m (a partir de esta profundidad, la temperatura se incrementa a razón de 3 ºC por cada 100 metros (Buzăianu et al, 2015;Graf et al, 2016) la temperatura del suelo es constante durante todo el año e igual a la temperatura media ambiente del lugar. Así, por ejemplo, en un clima subtropical como el español, donde, en general, la temperatura media anual es benigna, la VLEGE puede ser una fuente excelente de energía renovable para climatización.…”