Turbines and Mechanical Components

Federal manufacturing effort targets shorter wait times for large hydropower parts

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Federal manufacturing effort targets shorter wait times for large hydropower parts
(ORNL’s Jay Tiley inspects a hydroelectric runner from TVA’s Cherokee Dam. ORNL is partnering with TVA and others to develop a process to produce large metal components like this for clean energy applications. Credit: Jim Tobin/ORNL, U.S. Dept. of Energy)

A new federal manufacturing program for large metal parts aims to help revitalize American manufacturing and reduce waiting times for critical hydropower components.

The project — Rapid Research on Universal Near Net Shape Fabrication Strategies for Expedited Runner Systems, or Rapid RUNNERS — received U.S. Department of Energy funding of $15 million over three years to create a system to produce the large turbine runners used in hydropower plants.

Scientists from DOE’s Oak Ridge National Laboratory (ORNL) argue that the approach could “greatly” reduce waiting times for components and enable economic growth in the manufacturing sector for energy.

The project will produce runners using 3D printing, or additive manufacturing (AM), combined with conventional tools, all produced domestically. The process will use robotic welders to deposit metal layer by layer to form the runners. 

“This has the potential to transform forging and casting of large-scale metal components,” said Adam Stevens, an R&D staff member at ORNL and technical lead for the project.  

These large metal components are produced almost exclusively overseas, ORNL said, and when they fail, it can take years to fabricate and receive replacements. But, ORNL maintains that automated AM methods can quickly produce metal components that are close to the final dimensions of the parts, known as near-net-shape. Traditional machining techniques are then used to finalize the shape.

“Right now, it takes around 18 months to produce one of these. If you can’t operate a hydropower turbine because you’re waiting for a part, that’s 18 months of clean energy you’re not generating. This approach can fill the gap in the domestic industrial base,” Stevens said. 

Near-net-shape refers to the geometry of a component that is printed as close to final size and shape as possible, reducing the finishing steps that traditional metal fabrication requires. ORNL said convergent manufacturing provides a path toward achieving the desired net shape by incorporating necessary machining and finishing into the AM process. Turbines used for hydropower have complex designs and are complicated to produce, currently requiring months of manual welding and finishing.

To demonstrate the capability of the manufacturing system, the program will fabricate three stainless steel Francis runners. The first runner is a prototype to be used for testing. The second, about 5 ft in diameter, is being made for potential installation in the Tennessee Valley Authority’s Ocoee Dam in Parksville, Tenn. Ocoee Dam is an 840-foot-wide, 135-foot tall dam spanning the Ocoee River, with five turbine-generator units that provide total generating capacity of 24 MW.

The third Francis runner will be manufactured for potential installation in TVA’s Wilson Dam, which has 21 turbine-generator units with a total capacity of 653 MW. The turbine will be about 15 ft in diameter and 8 ft tall and weigh more than 46 tons. TVA, based in Knoxville, Tenn., is the largest public power company in the U.S., operating 113 power generators at 29 dams.

Central to the Rapid RUNNERS program is software that allows robots to produce the parts, working collectively to do AM at greater rates across larger shapes than an individual system. The envisioned system has one robot assigned to a task, such as wire arc welding, grinding, metrology and other necessary functions traditionally done by workers in large foundries and fabrication facilities. The system may have six or more robots converge on the system at the same time, according to a release.

Curt Jawdy, head of R&D at TVA, said this method may help them avoid the long wait time with traditional production. “All these foundries have a pretty big backlog, and we find that it takes two years from the time we place an order to the time we get a runner,” he said.

TVA said it expects that eventually, many of its turbines and steel components, in this case steel known as 410 stainless, will be produced domestically by AM processes.

This program covers development of the software, hardware, robotics and manufacturing strategies necessary to produce these large components. Partnering with ORNL on development are several organizations, in addition to TVA: Huntington Ingalls-Newport News Shipbuilding, where the largest Francis runner will be 3D-printed; the Electric Power Research Institute, contributing to technoeconomic analyses; Open Mind Technologies, assisting with manufacturing strategy development; ARC Specialties, providing robotic hardware and integration; and Voith Group-Hydropower, a hydro turbine manufacturer.