Engineering researchers will use NSF grant to revolutionize wave farm design, lowering cost of renewable energy

NREL Wave Array Illustration, showing multiple wave energy converters, connected to substations on- and off-shore.
Artist's impression of a wave energy farm. Illustration by Alfred Hicks, NREL.

Renewable energy has the potential to solve many societal problems. A new project by Colorado State University engineering faculty aims to improve U.S. energy security by making renewable energy more economically viable.

Three professors from the Civil and Environmental Engineering and Systems Engineering Departments have received a $529,000 grant from the National Science Foundation to make wave farms more competitive by optimizing their performance. Many other types of engineering systems will benefit from the models and design tools they develop.

“While this research will focus on application to plant/layout and control co-design of large-scale wave farms, the framework and methodologies are transferable to the design of other engineering systems, such as onshore and floating offshore wind turbines in wind farms, vehicle design, smart antennas and intelligent structures,” said Gaofeng Jia, principal investigator on the project and assistant professor in the Department of Civil and Environmental Engineering.

Performance falls short in current wave farm systems for two reasons: environmental uncertainties and the system and its control are designed separately. Integrating design of the physical system and its operational control, by considering the fundamental link between them, and accounting for environmental factors will improve the performance of wave farms.

Lots of moving parts

Graphic showing the multidisciplinary nature of the project. Courtesy of Gaofeng Jia.
Graphic showing the multidisciplinary nature of the project. Courtesy of Gaofeng Jia.

Wave farms are large collections of floating devices that resist ocean waves to produce power. These complex dynamic systems include many interacting wave energy converters. To produce enough power to be economically worthwhile, large numbers of wave energy converters need to be deployed in strategic layouts within the wave farm.

Designing and operating this type of system comes with a lot of inherent uncertainty. While ocean waves follow patterns, they can vary significantly in height and direction, so modeling the behavior of these many interacting devices moving in ocean waves is challenging.

“All of these characteristics factor into the systems design challenge where we want to select the best layout of the devices, their physical characteristics and their operational control,” said Dan Herber, co-PI and assistant professor in the Systems Engineering Department. “Developing the design and optimization techniques that address these challenges is a core part of this research effort.”

The control in this case is used to tune the dynamics of the wave energy converters based on wave conditions, so the wave energy converters can perform as well as possible. Traditionally, engineers from different disciplines designed the physical system and then the operational control. Control engineers had to make the physical design they were given operate. This method is costly and neglects the coupling between the two designs that factors into the best performance of each part.

“These sequential, handoff types of approaches are starting to be less desirable as systems become more complex, dynamic and integrated,” Herber said.

Better models are needed for integrated design, which the collaborators hope to achieve through this project.

Jia and co-PI Hussam Mahmoud, associate professor in the Department of Civil and Environmental Engineering, will create numerical models for wave energy converters and WEC arrays to assess wave farm performance and optimize output. Herber will develop robust control co-design formulations and algorithms for linking the system and control from the start.

Collaborators at the National Renewable Energy Laboratory, Yi-Hsiang Yu and Nathan Tom, who are developers of the open-source WEC modeling tool called WEC-Sim, will help address questions and issues in modeling WEC devices and arrays using WEC-Sim, as well as help integrate the algorithms developed in this project into WEC-Sim.

The Colorado Energy Research Collaboratory supported collaboration between the CSU faculty and NREL with a seed grant that allowed them to prepare some preliminary results for their NSF proposal.

Far-reaching impacts

Graduate students from both Civil and Environmental Engineering and Systems Engineering will have the opportunity to work on this state-of-the-art research. Select undergraduates also will be able to participate through NREL’s Science Undergraduate Laboratory Internship program.

The CSU team will partner with the National Energy Education Development program to create lessons based on their research. They hope that by training STEM educators in the innovative methods established through the project, they can help foster a globally competitive STEM workforce.

The methods and algorithms developed through this project will be shared as open-source tools for use by researchers and industry.

“This research will advance design science and advance national prosperity and welfare by helping to improve both economic and energy security, and by ensuring continued leadership and innovation in clean energy and system design,” Jia said.