- New milestone in Exergy's Radial Outflow Turbine (ROT) technology, boosting power output to 60 MWe on a single shaft - A competitive, high-efficiency solution for next-generation large-scale geothermal systems

Exergy International, a global leader in advanced geothermal binary power plants, today unveiled a new milestone in its proprietary Radial Outflow Turbine (ROT) technology: the Gemini Turbine.

This innovative configuration combines the power of two turbines into a single high-capacity unit delivering up to 60 MWe. Conceived and developed entirely in-house by Exergy's Turbine team in Italy, the Gemini sets a new benchmark for efficiency, scalability, and competitiveness in large-scale geothermal power generation, making it the ideal match for next- generation Enhanced and Advanced Geothermal Systems (EGS and AGS).

A New Architecture for Maximum Performance
At the heart of Gemini's innovation lies an evolution of Exergy's proprietary ROT architecture. The turbine features a dual-inlet design that allows the working fluid to enter symmetrically from both sides and expand radially outward through a central rotor disk equipped with dual mirrored rotor stages. After its radial expansion, the fluid converges toward a central exhaust flange for discharge.
In this new configuration, stator blades are mounted on lateral stator disks, while the rotor is supported in a between-bearings arrangement, replacing the traditional overhung setup. This structural advancement significantly enhances the turbine's mechanical stability, reduces vibration, and improves operational reliability.

Advantages and Key Benefits
The Gemini turbine's unique configuration delivers a series of technical, operational and economic
advantages providing real value for developers and operators:
• Capability to handle very high volumetric flows (exceeding 50 m³/s) on a single shaft
• Isentropic efficiency above 90%, equivalent to multi-turbine systems in one compact machine
• Simplified plant layout and reduced mechanical complexity
• Shaft locking system allowing easy and fast maintenance
• Reliability based on Exergy's proven ROT technology (>550 MWe installed worldwide)
• Up to 30% lower power plant cost than conventional multi-turbine configurations
• Reduced erection and civil-works with smaller footprint and higher sustainability
• Improved project economics with faster return on investment (ROI)

Luca Pozzoni, Deputy CEO of Exergy International commented: "The Gemini turbine marks a major
milestone in Exergy's technological evolution. It showcases the strength of our engineering expertise and the creativity of our team, who constantly push the boundaries of what our technology can achieve. With Gemini, we deliver a solution that offers higher performance, lower costs, and a reduced environmental footprint — all essential for the future of large-scale geothermal power".

Luca Vanini, Manager of Exergy's Turbine department added: "Continuous improvement is a key principle at Exergy. Rooted in an idea by our Turbine Engineer Giorgia Ruffato, the project of the Gemini was developed within our turbine department and refined through close collaboration across all our technical teams. It's an achievement that reflects both our innovation culture and our commitment to practical, high-performance solutions. Seeing it come to life is a proud moment for everyone involved".

Applications and Market Outlook
The Gemini Turbine opens new possibilities for harnessing geothermal resources with very high flow rates more efficiently, replacing traditional configurations that use two ROT turbines operating in parallel. It provides a competitive, cost-effective, and high-performance solution for large-scale geothermal power plants in the 30-60 MW range.
Gemini is particularly suited to next-generation geothermal systems based on EGS and AGS
technologies, which are emerging as the most promising frontier of global geothermal development. These systems enable power generation in regions previously considered unsuitable for geothermal use. Since 2017, investment in next-generation geothermal technologies has risen sharply — from negligible levels to nearly US$2 billion raised in 2024 (Wood Mackenzie)— driven by both private and public sector support. According to the International Energy Agency, global geothermal capacity could exceed 800 GW by 2050, supplying around 8% of the world's electricity —confirming geothermal energy as a key pillar in the world's clean-energy future.