Green energy is taking a step forward at Clemson University with new research that could help hasten the development of turbines that are fueled by hydrogen, the universe’s most abundant element.
Researchers aim to create a new type of coating that would armor turbine blades against intense heat and high-velocity steam, an environment so extreme it is not yet well understood and would vaporize many materials. Hydrogen burns hotter than other fuels with temperatures in the turbine inlet reaching about 1,700 degrees Celsius.
The project has the potential to help reduce the world’s reliance on burning fossil fuels, which has been linked to climate change. One advantage that hydrogen-fueled turbines have over other clean-energy sources, such as wind turbines and solar panels, is that hydrogen can be burned at will to generate power without having to worry about changes in the weather.
Fei Peng, an associate professor of materials science and engineering at Clemson, is the principal investigator on the project. Industry partners include Siemens Technology and Advanced Manufacturing, LLC.
“When we think long term and what the Earth will look like for our kids, we need to consider how we can generate clean energy in the future,” Peng said. “Our research is critical. Without that coating, a turbine could not survive the environment produced by hydrogen combustion.”
The bulk of the project’s funding, $800,000, comes from the U.S. Department of Energy’s Office of Fossil Energy and Carbon Management. Another $344,000 is coming from other sources.
The goal is to create a coating that will allow hydrogen-fueled turbines to operate for 32,000 continuous hours, even as the inlet temperature reaches 1,700 degrees Celsius, which is 150-200 degrees higher than current state-of-the-art technology allows.
A big part of the research focuses on better understanding combustion inside hydrogen-fueled turbines and how various materials behave in that environment.
One of the major challenges for researchers is ensuring the coating remains free of cracks and other defects that can allow steam to rush in and destroy the turbine blades.
Researchers’ vision is for the coating to be placed onto blades as a slurry and then sintered with a laser one point at a time, using a technique called laser-selective integrated additive/subtractive manufacturing, or (L-IASM), Peng said.
Hai Xiao, a collaborator on the project and the chair of Clemson’s Holcombe Department of Electrical and Computer Engineering, said researchers can selectively sinter ceramic materials at precise locations within seconds without overheating the rest of the part.
“Due to the extremely fast heating rate, the laser can sinter the ceramic coating to fully dense within seconds while keeping the substrate at relatively low temperatures,” Xiao said. “By adjusting the laser-processing parameter, we can precisely control the microstructure, including grain size and porosity, and eliminate defects, such as cracks, that can leave the turbine blade vulnerable.”
The current process for coating turbine blades, air plasma spray, makes it difficult to control the coating’s microstructure and defects, researchers said.
Most power-generating turbines are fired by natural gas, which burns cleaner than coal but remains a source of greenhouse gasses. Researchers around the world are developing alternatives to help meet government caps on emissions.
They have looked at using hydrogen alone or combining it with other fuels. Hydrogen is not only a clean energy but also a way to store renewable energy from the sun and wind.
The first step in the Clemson-led project is to characterize the thermal and mechanical properties of polymer-derived ceramics, yttrium silicates and gadolinium zirconate, all materials that show high promise for becoming part of a coating for turbine blades.
Then researchers will adjust laser-processing parameters for various material compositions. Once researchers have created coating samples, they will run the samples through a series of simulations and tests, using machine learning to evaluate the samples’ microstructure and defects, with the goal of creating a manufacturing process that is reliable and repeatable.
Huijuan “Jane” Zhao, a Stanzione Associate Professor of mechanical engineering at Clemson, plans to create high-fidelity, multi-physics models to design and predict the graded coating material behavior in a hydrogen-combustion environment.
“We will study the design parameters of the candidate materials such as layer thickness, porosity, thermal, and mechanical properties,” Zhao said. “These are the parameters I can adopt and optimize in the numerical simulations. With the support from the Palmetto supercomputing clusters, we can effectively optimize the graded coating design and guide the experimental fabrication and characterization.”
Siemens Technology researchers will focus on better understanding the combustion environment in the turbine.
“The project addresses much-needed environmental resistance of ceramic matrix composites that have been key enablers for ultra-high temperature power generation,” said Anand Kulkarni, a senior principal key expert at Siemens Technology. “The team will focus on advanced laser processing that will provide an opportunity for rapid screening of ceramic compositions utilizing combinatorial materials. Siemens Technology has been at the forefront in advanced materials and digital manufacturing, the expertise of which will be utilized within the project to facilitate conformal robotic deposition of coatings.”
Dongsheng Li, the founder of Advanced Manufacturing, LLC, will contribute his expertise in additive manufacturing and manufacturing qualification, maturation and commercialization.
“Ceramics composite is the one and only candidate for ultra-high-temperature application, but with many challenges, Advanced Manufacturing, LLC is advancing research and commercialization of additive manufacturing with passion, expertise and resource flexibility,” Li said. “The proposed gradient structure achieved by additive manufacturing will decrease property mismatch and increase product life expectancy.”
“Fei is a leading expert in using machine learning to guide advanced manufacturing of ceramics,” Brinkman said. “His previous research and scholarship, combined with our unique facilities, make Clemson the ideal place for this project.”
Anand Gramopadhye, dean of the College of Engineering, Computing and Applied Sciences, congratulated the team on securing funding for the research.
“A multidisciplinary team that includes industry collaborators is coming together to develop materials that help enable hydrogen-fueled turbines to produce sustainable energy,” Gramopadhye said. “The funding is a testament to the high level of scholarship that Dr. Peng and his team bring to the project. This is a well-deserved opportunity for the entire team.”