As part of our ongoing focus AM Focus 2021 on sustainability we’ve been looking at how 3D printers can help make energy generation cleaner and more efficient. One way is to help the development of next-generation nuclear power plants, another is by making fossil fuel-based energy production cleaner and more efficient. Yet another is by helping develop more efficient renewable energy generation systems. One segment where AM applications are still hard to find is geothermal energy. Now Enel, the largest energy company in Italy (the Italian State is the main shareholder with 23%), through its Enel Green Powder division, showed how 3D printers can help geothermal energy plants run more smoothly and efficiently by providing replacement parts at dramatically reduced costs.
The success story recently involved Enel’s Santa Barbara metallurgy labs in Cavriglia, near Arezzo, as part of its Enel’s Geyser project. This project is dedicated to geothermal energy, one of the renewable sources that has been in use the longest; Italy—and Enel Green Power—are leaders in this field.
Geyser’s aim is to optimize the management of geothermal plants, ensuring their sustainability and full functionality, increasing their operational efficiency and constantly improving their technical and financial performance, all while paying full attention to safety and the environment.
The team working on the project organized a round table of technicians and experts from the geothermal, thermal and hydroelectric sectors. That is where the idea originated to use a 3D printer for the first time to repair an essential component of a geothermal power plant.
Leveragin in-house resources
“It all started from our curiosity and desire to use the 3D printer that we had in-house,” said Nicoletta Mazzuca, Enel Green Power’s Project Manager for Geyser, which is developing around 42 initiatives involving over 80 people. “We wanted to repair parts that were going to end up in landfills because they couldn’t be fixed with conventional forging techniques. But, thanks to our colleagues’ passion, competence, and cooperation, we found a solution.”
The 3D printer is supplied by Prima Additive, and Enel actively participated in its development (as reported by our Italian sister site Replicatore). The LMD machine (Prima Additive also offers metal LPBF technology) is located in the Santa Barbara metallurgy labs, at the headquarters of Engineering and Technical Support for Enel Production, and has been available since 2019. This extremely high-tech tool can reproduce and repair various metal parts by depositing the necessary material one layer at a time.
“The fact that the printer is in an area that also has a metallurgy lab provides immense added value. In this way, the additive manufacturing process can be monitored almost in real-time, checking the mechanical, chemical and metallurgical properties of the items manufactured so we can also count on constant feedback,” explained Giulio Andrucci, Technical Leader and coordinator of the Santa Barbara metallurgy lab.
The printer was used to repair an impeller, which is an essential component of the centrifugal compressor of a geothermal plant because it extracts non-condensable gases from the vapor at the end of the expansion process in the turbine. Non-condensable gases contain solid particles and water droplets that impact the blades, wearing out the exterior of the intake profile.
A geyser of benefits
The pilot project began with the purchase of a powdered form of the material used to make the impellers (stainless steel 17-4 PH), followed by laser scans and the creation of the 3D model. The work was carried out by a team led by Gennaro Raniello, Head of Hydro Maintenance Support – O&M Hydro Italy at Enel Green Power, and it concluded with the first historic repair of a worn part thanks to this technology. The result is sustainable innovation that will make it possible to set in motion a cycle of reuse of materials: until now, worn impellers were simply replaced with new ones and ended up in landfills, so repairing them will also save around €70,000 per year.
The economic calculation factors in the restoration of four out of six impellers, on average, that break every year in its geothermal plants. This estimate takes into account that the damage might be too significant in some cases, so two out of six might not be repairable at all. “After a year of work, we were able to use additive manufacturing processes to repair our impellers for the first time. Not only does it give our impellers a second life, but it also saves us money while respecting the environment thanks to 100% circularity. I am honored to have participated in the creation of this innovative repair process and I would like to thank my colleagues for teaching me so much in such a short time,” added Nicoletta Mazzuca.
“The Geyser project allowed us to introduce and share the competencies available in several poles of excellence from Enel’s various supply chains in Italy,” explained Matteo Niccolai, Workshop Maintenance and Technical Services Leader – O&M Geo Italy of Enel Green Power. “The idea of using additive manufacturing to solve one of Geo’s supply chain issues is a concrete example of the effectiveness of sharing problems and best practices transversally within the company, solving critical issues with the help of previously unseen perspectives.”
This is a success story that further enhances the centuries-old history of geothermal power in Italy, where EGP operates the oldest and most innovative power station complex in the world, with 34 plants located in the Tuscan provinces of Pisa, Siena, and Grosseto.
Digging deeper into AM for geothermal
Looking towards the future of AM in geothermal energy, a just-published study from Oak Ridge National Laboratory in the US discussed how additive manufacturing can make the design and production of specialized tools for geothermal energy cheaper and more efficient.
Geothermal is a renewable energy resource that requires specialized tools for drilling in harsh subsurface environments. The tools are typically produced in low quantities at high cost using conventional fabrication.
By using 3D printing techniques, geothermal companies can take advantage of computer-aided technologies to design tools with enhanced performance characteristics. Those custom parts can then be printed using ORNL’s high-strength alloys at a lower cost, especially when printing multiple parts in a single build. The lab’s techno-economic analysis found ample opportunity to lower the cost of geothermal projects while improving system performance using additive manufacturing.
“The study points to the significant benefits of additive manufacturing and provides a roadmap for future work, including the development of new AM feedstocks based on advanced, high-temperature alloys,” said ORNL’s Yarom Polsky.