ORNL leads $15M project to revolutionise large-scale Additive Manufacturing for hydropower components
September 9, 2024
The US Department of Energy’s Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, USA, has announced a manufacturing programme for large metal parts. This initiative is said to show the potential to revitalise American manufacturing and bring clean energy manufacturing technologies back to the United States. The approach could greatly reduce waiting times for critical components and enable economic growth in the manufacturing sector for energy, according to scientists at the Department of Energy’s Oak Ridge National laboratory.
The project “Rapid Research on Universal Near Net Shape Fabrication Strategies for Expedited Runner Systems” (Rapid RUNNERS) has received $15 million in funding from the DOE over three years. The project aims to develop a system for producing the large runners (the rotating part of a turbine that converts water pressure and movement into electricity) used in hydropower dam turbines.
The project will produce runners using Additive Manufacturing 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 predominantly manufactured overseas. When they fail, it can take years to fabricate and receive replacements, resulting in lost time, money, and renewable energy. For every month a hydropower turbine is idled waiting for components, thousands of megawatt-hours of renewable electricity are forfeited. However, automated Additive Manufacturing 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 finalise the shape, reducing waste and downtime compared to existing processes.
“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 shared.
Near-net-shape refers to the geometry of a component that is manufactured s close to final size and shape as possible, greatly reducing the finishing steps that traditional metal fabrication requires. 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 finishing.
Brian Post, leader of ORNL’s Disruptive Manufacturing Systems Development group, and Jay Tiley, head of the lab’s Materials Structures and Processing Section, are project principal investigators for systems and materials, respectively. The Manufacturing Demonstration Facility at ORNL is providing resources and expertise. The MDF, supported by DOE’s Advanced Materials and Manufacturing Technologies Office, is the hub for a nationwide consortium of collaborators working with ORNL to innovate, inspire and catalyse the transformation of US manufacturing.
To demonstrate the capability of the manufacturing system, the programme will fabricate three Francis runners, a particular style of large stainless-steel turbines used in dams to generate hydropower. The first runner is a prototype to be used for testing. The second, about 5 feet in diameter, is being made for potential installation in the Tennessee Valley Authority’s Ocoee Dam in Parksville, Tennessee. The Ocoee Dam is an 840-foot-wide, 135-foot tall hydropower dam spanning the Ocoee River with five generating units that produce 24 megawatts of electricity.
The third Francis runner will be manufactured for potential installation in TVA’s Wilson Dam, which has 21 generating units producing 653 megawatts of electricity. The turbine will be about 15 feet in diameter, 8 feet tall and weigh more than 46 tons. TVA, based in Knoxville, Tennessee, is the largest public power company in the nation, operating 113 power generators in 29 dams.
“We are always looking for new ways to do things better. Innovation is a part of TVA’s DNA, and it’s something that we focus on in all things we do,” said Joe Hoagland, TVA’s vice president of innovation and research. “This programme offers an innovative way for us to fulfil TVA’s mission summarised by three ‘E’s: for Energy, it improves reliability, for the Environment, it maximises renewable energy produced, and for Economic development, it brings great jobs back to the US.”
Central to the programme is software that allows robots to produce the parts, working collectively to do AM at greater rates across larger shapes than any 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. Six or more robots may converge on the system at the same time.
Traditional production of these runners, all overseas, takes a lot of time and is very labour intensive, said Curt Jawdy, head of R&D at TVA, “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.”
TVA 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, which enable unique capabilities.
Jawdy mentioned that hydro runners have areas prone to cavitation, which can lead to turbine failure due to erosion of the vane surfaces from collapsing air bubbles. However, through AM, a cavitation-resistant coating can be applied.
“You can do things with Additive Manufacturing that you can’t do otherwise. There are shapes you can make that you would not be able to make otherwise, and you can combine materials,” Jawdy said.
The programme covers developing the software, hardware, robotics and manufacturing strategies necessary to produce these large components. In addition to TVA, several organisations partner with ORNL on development. These include Huntington Ingalls-Newport News Shipbuilding, where the largest Francis runner will be additively manufactured; the Electric Power Research Institute, contributing to techno-economic analyses; Open Mind Technologies, assisting with manufacturing strategy development; ARC Specialties, providing robotic hardware and integration; and Voith Group-Hydropower, a hydro unit manufacturer.
At the end of the three-year term, the project will have created a new distributed hybrid-manufacturing platform that could be used by many industries, “that will allow for domestic production of infrastructure-scale net-shape components for energy, defence, ship building, hydropower and municipal water supply – any industry that requires a large piece of metal could benefit from this,” ORNL’s Stevens said. “This will increase worker productivity and provide a healthier domestic industrial base.”
The DOE award consists of $13 million from the Advanced Materials and Manufacturing Technologies Office, and $2 million from DOE’s Water Power Technologies Office.
Download Metal AM magazine
