Composite Use in Geothermal Energy Facilities

Composite Use in Geothermal Energy Facilities Geothermal energy is one of the most important alternative energy sources. Today, with diminishing resources and climate crisis, the use of renewable energy sources and the need for such sources has increased. Geothermal energy is a renewable, inexhaustible and environmentally friendly energy source. The use of composite materials in geothermal energy facilities is increasing steadily. The reason for this is that composite materials offer certain advantages compared to other materials. Geothermal is derived from the combination of the English words geo (earth) and thermal (heat). Looking at the Turkish equivalent of the term, we can call it ground heat. The heat accumulated within the Earth's crust is generally called geothermal. Natural hot water, steam and gases containing many different elements and other substances are called geothermal fluid. The energy possessed by these fluids and created by heat is called geothermal energy. Geothermal liquids can vary depending on the source. Liquid composition is often influenced by the macro elements contained in surface environment and reservoir rocks exposed by the liquid. The most commonly observed components in these liquids are; Na⁺, K⁺, Ca²⁺, Mg2+, Cl^-, SiO₂, HCO^{3 -}, CO₃ ^-, SO₄ ^2- and CO₂. These components have significant effects on materials used in geothermal systems. Compared to traditional pipe materials carrying these geothermal fluids, composite materials exhibit great resistance to the effects caused by these components. Due to the components contained in geothermal liquids, damage such as corrosion and scaling can occur, particularly in carrier pipes. The damage that occurs can create major economic losses in geothermal energy production. Composite materials have high durability and mechanical performance. For this reason, less damage is observed in composite carrier pipes. Particularly fiberglass composites are frequently used in geothermal energy facilities. In addition to composite materials, carbon steel, stainless steel, mild iron, PVC and PE are used in carrier pipes. Compared to these materials, composites have the highest durability. At the same time, while fracture and creep can occur in other materials, composite materials show high resistance to corrosion. Carbon steel and stainless steel can withstand temperatures up to 370 degrees but are vulnerable to corrosion and can change shape. On the other hand, composites can withstand temperatures up to 150 degrees but do not change shape. With these properties, composite materials can prevent damage and material losses that would occur in geothermal energy facilities. Composite materials are used at the Çeşme Geothermal Energy Facility in Turkey. Following inspections carried out at this facility, the durability of composites has been demonstrated. The shift towards alternative and renewable sources such as geothermal energy is of great importance. The materials to be used in these facilities are important in terms of facility lifespan, durability and adequacy. References • Metin Tanoğlu - Composite Materials and Geothermal Applications • Polymer-cement composites with self-healing ability for geothermal and fossil energy applications ; M Ian Childers, Manh-Thuong Nguyen, Kenton A Rod, Phillip K Koech, Wooyong Um, Jaehun Chun, Vassiliki-Alexandra Glezakou, Diana Linn, Timothy J Roosendaal, Thomas W Wietsma, Nicolas John Huerta, Barbara G Kutchko, Carlos A Fernandez • Metin Tanoğlu, Murat Toğulga, Gülden Gökçen - Mechanical Properties of Composite Pipes and Experimental Analysis of Durability in Geothermal Fluid Environment Prepared by: Nilsu Kotil