Geothermal power plants often use reservoirs to store and manage hot water and other geothermal fluids used in power generation. By capturing and storing used fluids for reuse, power plant operators can ensure a consistent supply is available for electricity production. Advanced geomembranes line the reservoirs to keep the fluids contained, prevent leaks, and avoid damage to the surrounding environment. An appropriate, high-quality liner is essential for protecting ecosystems and maintaining the long-term sustainability of geothermal energy production. Let’s look at the key challenges liners must contend with and a few examples of the available materials.
Importance of Reservoir Liners
Geothermal reservoirs are the heart of any geothermal power plant but are not without challenges. Geothermal fluids can be highly corrosive, threatening the environment and the longevity of the reservoir itself. In addition, efficient and sustainable energy production depends on maintaining optimal conditions within the reservoir. This is where advanced liners come in.
Preventing Fluid Loss and Maintaining Reservoir Pressure
In geothermal reservoirs, where fluids constantly flow in and out, advanced geosynthetic liners prevent fluid loss so operators can maintain optimal pressures for efficient heat extraction.
Environmental Protection
Geothermal fluids often contain dissolved minerals, salts, and other substances that can critically degrade ground and surface water supplies if released. In addition, geothermal fluids are frequently still hot after they’ve exited the power plant. If these hot, contaminated fluids were allowed to flow freely into nearby surface waters, the combined thermal and chemical pollution could devastate local and downstream ecosystems. The use of impermeable liners mitigates both threats.
Economic Benefits
Reservoir liners play an important role in helping geothermal projects operate in the green. They maintain fluid levels, reduce maintenance costs, and extend the lifespan of geothermal wells, all of which help maximize energy production and minimize operational expenses.
Types of Geothermal Reservoirs
Geomembrane liners are commonly employed in four broad reservoir categories: surface impoundments, constructed underground reservoirs, Enhanced Geothermal System (EGS) surface reservoirs, and reinjection ponds or basins.
Surface Impoundments (Ponds/Lagoons)
Surface impoundments are the most common type of geothermal reservoir. Constructed at ground level using earthen embankments, they store geothermal fluids before reinjection, manage waste brines, and retain extracted fluids as they cool before discharge. Surface impoundments are popular because they’re relatively easy to build and maintain. In these surface impoundments, impermeable geomembrane liners prevent fluids from seeping into the ground, which minimizes fluid loss and protects groundwater resources. However, their exposure to the elements brings challenges like high evaporation rates, liner weathering from UV radiation and temperature fluctuations, sedimentation from windborne dust, and potential damage from wildlife.
Constructed Underground Reservoirs (Tanks/Excavated Caverns)
Unlike surface impoundments, constructed underground reservoirs offer a more contained environment and protection from the elements and surface-level disturbances. They’re often built from concrete or steel, which provide structural integrity but may not be impermeable to liquids or resistant to corrosive elements in the geofluids. Geomembrane liners add an impermeable and chemically resistant layer between the harsh fluids and the containment structure, which protects it from degradation and the risk of failure.
Geomembrane-lined tanks and underground reservoirs are an attractive option when space is limited or when minimizing surface evaporation is crucial. However, they require more complex construction and excavation and introduce new challenges, including managing external groundwater pressure, limited maintenance access, the potential for undetected leaks, and damage from ground settlement.
Enhanced Geothermal System (EGS) Surface Reservoirs
Enhanced Geothermal System surface reservoirs are specially designed for EGS operations, where they play a critical role in maintaining fluid balance and maximizing heat extraction. Because of the unique characteristics of EGS fluids, these reservoirs require geomembrane liners with specialized properties, such as high chemical and thermal resistance. Surface reservoirs may experience more frequent fluctuations in fluid levels and temperatures, which should also be considered when selecting the liner material.
Reinjection Ponds/Basins
Reinjection ponds or basins store and treat fluids before reinjection, an essential practice for maintaining sustainable operations and preventing land subsidence. Geomembrane liners in reinjection ponds must be compatible with the chemical composition of the fluids and any treatment processes used. Reinjection ponds typically require more complex design and construction than other types of surface impoundments, as they may need to include features for sedimentation, filtration, or chemical treatments and are subject to stringent environmental regulations.
XR Elastomeric Alloy Geomembranes – High-Performance Liners for Geothermal Reservoirs
In the uniquely demanding environment of geothermal energy production, the reservoir liner directly affects long-term performance, operational efficiency, and reliable environmental protection. BTL Liners’ XR Geomembranes are engineered to excel in the unique challenges geothermal applications pose.
Unmatched Chemical Resistance
Geothermal fluids often contain a complex mix of dissolved minerals, salts, and gases, which can be highly corrosive. Premium XR Geomembranes are formulated to withstand these aggressive chemicals and perform reliably for decades of heavy use. We’re happy to help you find the ideal containment solution for the challenging liquids you’re working with.
Exceptional Thermal Stability
While fluids may have cooled by the time they reach the reservoir, temperatures can still fluctuate significantly. XR Geomembrane liners are designed to maintain their integrity and flexibility across a wide temperature range, preventing thermal stress and ensuring consistent performance. We’re happy to review the verified thermal resistance of each of our products with you.
Superior Durability and Strength
BTL’s liners are engineered to withstand the rigors of geothermal operations, from surface impoundments to underground reservoirs. The high tensile strength, puncture resistance, and tear resistance of our ArmorPro products provide exceptional durability, minimize leak risk, and ensure long-term containment at half the weight of traditional options.
Looking Ahead
We’ve seen how high-performance geomembrane liners help manage geothermal process fluids. But byproducts (waste) seem to be an inevitable part of any endeavor. Join us as we explore geothermal waste containment and management. We’ll examine the challenges presented by geothermal waste and explore how advanced geotextiles can help create secure and environmentally sound containment solutions.
