Geothermie in Europa

How a 3D printer brought a modern solution to the centuries-old history of Italian geothermal power

15.06.2021

An additive manufacturing machine has been used for the first time to repair a component of geothermal power plant in Italy. A perfect example of circular economy.

What do geothermal power, a 3D printer, and the circular economy have in common? They are the components of a success story in Cavriglia, near Arezzo, Italy, as part of the «Geyser project». This project from the company Enel Green Power is dedicated to geothermal energy. Its 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.

«Desire to use a 3D printer»
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. «It all started from our curiosity and desire to use the 3D printer that we had in-house,» says 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 solution is located in the Santa Barbara metallurgy labs, at the headquarters of Engineering and Technical Support for Enel Production, where an additive manufacturing machine with Laser Metal Deposition (or Direct Energy Deposition) technology 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.

Repair an impeller instead of replacing it
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.

The pilot project began with the purchase of a powdered form of the material used to make the impellers (a special kind of stainless steel called 17-4 PH), followed by laser scans and the creation of the 3D model. 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 the 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, it also saves us money while respecting the environment thanks to a circularity of 100%.,» added Nicoletta Mazzuca.

Source: https://www.enelgreenpower.com/media/news/2021/05/geyser-project-geothermal

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