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Geothermal power plants
Geothermal energy is an abundant resource available as heat energy contained in the earth’s crust in many regions of the world at various depths and temperatures. This heat can be harnessed to produce carbon-free electricity using geothermal power plants. Today, the total installed geothermal capacity worldwide is around 16 GWe, with the USA, Indonesia, the Philippines, and Turkey leading the way.
Geothermal energy is the most stable, versatile, and reliable renewable resource, with tremendous untapped potential ready for exploitation. Learn more about the advantages of geothermal energy.
THE GEOTHERMAL ORC PROVIDER WITH THE SECOND LARGEST GEOTHERMAL BINARY FLEET WORLDWIDE
Binary Cycle Power Plant
There are three main power plant technologies to harness geothermal resources: flash steam power plants, the most common and widely employed, dry steam plants, and binary cycle power plants.
Growing demand for power production from geothermal resources at medium-low temperatures has made the binary power plant (or ORC power plant), the preferred technology over flash steam solutions in recent decades.
With the Radial Outflow Turbine technology, Exergy offers highly efficient, reliable and tailor-made geothermal binary plants and has a portfolio of 500 MWe of geothermal power installed or under construction today.
Thanks to comprehensive experience with different geothermal resource and environment conditions, and with a wide array of power plants solutions and turbine sizes, we are able to offer high technical expertise to our customer and help them harness their full geothermal potential.
How a binary cycle geothermal power plant works
In binary power plants, in contrast to flash power plants, the geothermal fluid or steam from the geothermal reservoir never comes in contact with the turbine and the generator. The geothermal fluid and a secondary (hence “binary”) organic fluid pass through a heat exchanger. The heat from the geothermal fluid causes the secondary fluid to flash to vapour, which then drives a turbine and finally produces electricity at the generator. The secondary working fluid is then condensed and repressurised to complete the cycle, while the geothermal fluid is pumped back to the injection well.
Binary-cycle power plants are closed-loop systems with no emissions to the atmosphere.
Exergy’s ORC systems can be applied in diverse resource conditions and plant configurations:
EXERGY’s GEOTHERMAL ORC systems are available from 1 MW modular units to tailor-made plants up to 50 MW
Thanks to the ROT technology, Exergy's ORC geothermal plants offer several advantages:
STANDARD MECHANICAL DESIGN FOR EACH TURBINE FRAME
The fluid dynamic design of each turbine is optimized in order to reduce supply time, guaranteeing maximum efficiency without the need for mechanical redesign of the turbine
MULTIPLE PRESSURE ADMISSIONS POSSIBLE ON A SINGLE DISK
20% more power than a single level system with a simple configuration
Suitable for temperature heat sources as low as 90°C
UP TO 9 STAGES ON A SINGLE-DISK TURBINE
Extreme flexibility for changing geothermal fluid conditions, in terms of flow, temperatures and constituents
PORTFOLIO
500 MW
PLANTS
32
AVERAGE PLANT SIZE
16 MWe
AVERAGE AVAILABILITY
99%
TOE/Y SAVED
662174
Multi-pressure-level geothermal binary systems with radial outflow turbine technology
Binary geothermal power plants can feature multi-pressure-level cycle systems. This cycle configuration offers a significant increase in power output and cycle efficiency. Technologically advanced multi-pressure-level geothermal binary systems traditionally available on the market require at least one turbine per pressure level. The Exergy Radial Outflow Turbine, thanks to its unique single-disk and multi-stage configuration, allows multiple pressure level cycles to be expanded on a single-disk overhung turbine.
The geothermal fluid flows through the first sequence of HIGH pressure heat exchangers, transferring heat to the organic fluid. This organic fluid vaporizes and flows into the HIGH pressure turbine Inlet. Then the geothermal fluid flows through the second sequence of LOW pressure heat exchangers, vaporizing the organic fluid, which is then admitted into the LOW pressure turbine Inlet. The Exergy Radial Outflow Turbine (ROT), fed by HIGH and LOW pressure organic fluids, drives a generator to produce electrical power. The geothermal fluid is then re-injected back into the ground and the cycle continues.
ORC combined cycle in flash steam power plants
In single flash steam power plant operation, a significant part of the total thermal capacity is lost in the liquid phase (brine). Combining an ORC with a single flash power plant is possible to safely and efficiently recover energy contained in the brine that would otherwise be wasted to generate additional electricity.
This solution can boost the efficiency of an existing geothermal installation by increasing the steam field rated electrical power output with no additional environmental impact.
