Oct 29, 2025
Exergy introduces a high-capacity turbine aimed at Enhanced and Advanced Geothermal projects.
Exergy International has introduced the Gemini Turbine, a powerful turbine capable of generating up to 60 MW from a single unit using the company's Radial Outflow Turbine (ROT) technology.
Developed entirely in-house by Exergy’s Turbine team in Italy, the Gemini establishes a new standard for efficiency, scalability, and competitiveness in large-scale geothermal power generation, making it well-suited for next-generation Enhanced and Advanced Geothermal Systems (EGS and AGS).
Maximizing performance through new architecture
The innovation of Gemini is based on an advancement of Exergy’s proprietary ROT design. It features a dual-inlet structure that allows the working fluid to enter symmetrically from both sides and expand radially through a central rotor disk with dual mirrored rotor stages. After expansion, the fluid converges at a central exhaust flange for discharge.
In this design, stator blades are mounted on lateral disks, with the rotor supported in a between-bearings arrangement, replacing the traditional overhung design. This enhancement significantly boosts the turbine’s mechanical stability, minimizes vibration, and increases operational reliability.
Key advantages and benefits
The Gemini turbine’s distinctive design offers numerous technical, operational, and economic benefits for developers and operators:
- Ability to handle very high volumetric flows (over 50 m³/s) on a single shaft
- Isentropic efficiency exceeding 90%, comparable to multi-turbine systems in a compact form
- Simplified plant layout with reduced mechanical complexity
- Quick and easy maintenance enabled by a shaft locking system
- Reliability backed by Exergy’s established ROT technology (>550 MWe installed globally)
- Up to 30% lower power plant costs compared to traditional multi-turbine setups
- Decreased erection and civil-works requirements with a smaller footprint and greater sustainability
- Enhanced project economics with quicker return on investment (ROI)
Applications and market potential
The Gemini Turbine enables more efficient exploitation of geothermal resources with very high flow rates, replacing conventional setups that use two ROT turbines in parallel. It offers a competitive, cost-effective, and high-performance option for large-scale geothermal power plants in the 30–60 MW range.
Gemini is especially suitable for next-generation geothermal systems utilizing EGS and AGS technologies, which are becoming the most promising frontier in global geothermal development. These systems facilitate power generation in areas previously deemed unsuitable for geothermal energy.
“The Gemini turbine represents a significant milestone in Exergy’s technological advancement, highlighting our engineering expertise and the creativity of our team, who continuously push the limits of our technology. With Gemini, we provide a solution that delivers enhanced performance, lower costs, and a smaller environmental impact—essential for the future of large-scale geothermal power,” stated Luca Pozzoni, Deputy CEO of Exergy International.
“Continuous improvement is fundamental at Exergy. The idea for Gemini originated from our Turbine Engineer Giorgia Ruffato, and the project was developed within our turbine department through collaboration among all technical teams. This achievement reflects our culture of innovation and dedication to practical, high-performance solutions. Witnessing its realization is a proud moment for everyone involved,” added Luca Vanini, Manager of Exergy’s Turbine Department.
Developed entirely in-house by Exergy’s Turbine team in Italy, the Gemini establishes a new standard for efficiency, scalability, and competitiveness in large-scale geothermal power generation, making it well-suited for next-generation Enhanced and Advanced Geothermal Systems (EGS and AGS).
Maximizing performance through new architecture
The innovation of Gemini is based on an advancement of Exergy’s proprietary ROT design. It features a dual-inlet structure that allows the working fluid to enter symmetrically from both sides and expand radially through a central rotor disk with dual mirrored rotor stages. After expansion, the fluid converges at a central exhaust flange for discharge.
In this design, stator blades are mounted on lateral disks, with the rotor supported in a between-bearings arrangement, replacing the traditional overhung design. This enhancement significantly boosts the turbine’s mechanical stability, minimizes vibration, and increases operational reliability.
Key advantages and benefits
The Gemini turbine’s distinctive design offers numerous technical, operational, and economic benefits for developers and operators:
- Ability to handle very high volumetric flows (over 50 m³/s) on a single shaft
- Isentropic efficiency exceeding 90%, comparable to multi-turbine systems in a compact form
- Simplified plant layout with reduced mechanical complexity
- Quick and easy maintenance enabled by a shaft locking system
- Reliability backed by Exergy’s established ROT technology (>550 MWe installed globally)
- Up to 30% lower power plant costs compared to traditional multi-turbine setups
- Decreased erection and civil-works requirements with a smaller footprint and greater sustainability
- Enhanced project economics with quicker return on investment (ROI)
Applications and market potential
The Gemini Turbine enables more efficient exploitation of geothermal resources with very high flow rates, replacing conventional setups that use two ROT turbines in parallel. It offers a competitive, cost-effective, and high-performance option for large-scale geothermal power plants in the 30–60 MW range.
Gemini is especially suitable for next-generation geothermal systems utilizing EGS and AGS technologies, which are becoming the most promising frontier in global geothermal development. These systems facilitate power generation in areas previously deemed unsuitable for geothermal energy.
“The Gemini turbine represents a significant milestone in Exergy’s technological advancement, highlighting our engineering expertise and the creativity of our team, who continuously push the limits of our technology. With Gemini, we provide a solution that delivers enhanced performance, lower costs, and a smaller environmental impact—essential for the future of large-scale geothermal power,” stated Luca Pozzoni, Deputy CEO of Exergy International.
“Continuous improvement is fundamental at Exergy. The idea for Gemini originated from our Turbine Engineer Giorgia Ruffato, and the project was developed within our turbine department through collaboration among all technical teams. This achievement reflects our culture of innovation and dedication to practical, high-performance solutions. Witnessing its realization is a proud moment for everyone involved,” added Luca Vanini, Manager of Exergy’s Turbine Department.