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Oct 14, 2024

Redefining geothermal power generation with the Plain Bearings Turbine (PBT)

The new Plain Bearings Turbine (PBT) by Ormat aims to make geothermal power plants more efficient, simplify maintenance, and reduce downtime. Global geothermal developer and operator and technology

The new Plain Bearings Turbine (PBT) by Ormat aims to make geothermal power plants more efficient, simplify maintenance, and reduce downtime.

Global geothermal developer and operator and technology leader Ormat Technologies Inc (Ormat) recently announced the launch of the Plain Bearings Turbine (PBT), an innovative turbine designed to set new standards in reliability and ease of maintenance, as well as power capacity.

With this new addition in their portfolio, Ormat is again pushing the boundaries of technology to contribute to the growth of the geothermal power generation sector.

To learn more about the PBT and the operating principles behind it, we spoke with Nirit Grushko, Senior VP of Innovation, R&D, and Engineering and Alex Katz, Senior R&D Engineer of Ormat.

The value proposition of the PBT is quite simple and straightforward – it is a turbine that requires maintenance only once in 10 years. Even when maintenance has to be done, the new design allows it to be done much simpler and quicker than industry standards.

What is about the PBT that gives it this advantage? A standard overhung turbine has a set of bearings located on the generator side. To service or replace those bearings during maintenance, the turbine must be opened. While performed only every few years, this job requires substantial downtime.

In contrast, the PBT has both bearing assemblies located at points of the turbine that can be accessed externally. The PBT also makes use of robust hydrodynamic bearings (instead of the standard roller bearings), which theoretically will outlive the standard life of geothermal power plants.

The mechanical seal of the turbine – also one of its common points of failure – is also externally accessible. In addition, the design exposes the seal to lower temperatures, thus extending its useful life.

The result is a turbine that can undergo maintenance only once every 10 years, instead of the standard 4 to 7 years recommended for standard turbines. This period can be stretched out longer if there are no indicators that the turbine needs maintenance.

Another gain from the design is that the turbine no longer needs to be evacuated during maintenance. This is crucial when handling the binary fluid medium in ORC power plants. Not only does this avoid potential emissions of hydrocarbon compounds, but also makes the maintenance process easier for personnel

Although designed for ORC power plants, the higher capacity, ease of maintenance, and efficiency of the PBT mean that it can compete with steam turbines.

The capacity of the PBT caps at 50 MW, mostly because two of these reach the limit of the generators used in the binary market. However, smaller capacity PBTs can be supplied. Ormat currently has a prototype with an installed nominal power capacity of only 5 MW.

Whereas most turbines currently in the market support a maximum of 5 stages, the PBT design expands this possibility to 7 stages. This provides additional operational flexibility suitable to a wider geothermal market.

Ormat is currently focusing on targeting the high-temperature geothermal market, such as in Indonesia and New Zealand, for the PBT. This is a bold move as ORC turbines are typically utilized for low-temperature geothermal resources or the residual heat from the bottom stream of a steam turbine.

As a vertically integrated geothermal company with decades of experience, Ormat’s dual roles as an operator and engineering company have both played crucial roles in coming up with innovative products like the PBT.

“As an operator, all the things that hurt our customers hurt us as well. These include downtimes, maintenance, accessibility, time to evacuate, and emissions,” said Alex Katz. Having direct access to feedback from operational personnel provides both the input and incentive to come up with solutions to these pain points.

As a provider of technology and engineering solutions, Ormat develops products that build upon older products and lessons. In the case of the PBT, the design was based on improvements of at least two of their older turbine designs. By taking inspiration and lessons from past products, Ormat is able to refine the designs and take advantage of this iterative loop of innovations and constant improvement.

“Ormat has been around now for over 60 years, and we want to still be the leading company in geothermal for the next 60 years,” said Nirit Grushko. Innovation is a crucial part of achieving this goal. For this reason, coming up with engineering challenges is simply part of the company’s DNA.

“To keep our engineers curious, engaged, and motivated, we need to give them challenges. And if the challenge is easy, then it’s not a challenge,” added Grushko.

The company presents its engineers with a major challenge that initially seems impossible to achieve. To support them, they are provided with various tools, including training in systematic innovation thinking, design and entrepreneurial thinking, attendance at conferences, participation in roundtable discussions, and brainstorming sessions. This culture of continuous learning and collaboration was key to making the groundbreaking turbine design a reality.

The new PBT is part of Ormat’s campaign to make geothermal more competitive by reducing costs. This not only involves reducing drilling costs, but also making power plants more efficient and reducing costs associated to manufacturing, design, and construction.

Ormat maintains a very active pipeline of R & D projects addressing just about very major engineering challenge in geothermal. With its global footprint, access to different geothermal markets, and a company culture built on innovation, we likely will hear more groundbreaking product launches from Ormat in the near future.

For more information on the Plain Bearings Turbine, check out this video published by Ormat:

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