In research, I’m interested in tackling engineering challenges to energy sustainability through the use of innovative modelling, testing, and design optimization techniques. Current research activities are in wind and marine renewable energy, and in sustainable energy systems.
Much of my research background is in floating offshore wind turbines, a nascent technology that is both very promising economically and very challenging technically. Putting wind turbines on floating support structures can allow wind energy to be harvested over deeper waters, dramatically expanding the feasible wind resource in North America and around the world. My research has sought to contribute along several lines: design optimization techniques, better simulation tools, and more versatile testing capabilities.
This is an area of research I remain active in, continuing several projects, and identifying applications in other offshore renewable energy technologies such as wave and tidal power, as well as to offshore structures in general.
An ongoing research interest is hybrid modelling — combining simulations and experiments to better model floating wind turbines and other marine structures. I developed a real-time coupling of numerical and physical models, which can be used to provide a more versatile representation of aerodynamic forces when testing floating wind turbine designs at small scale in wave basins. In 1:50-scale tests at the University of Maine, we demonstrated than an actuation system coupled with a real-time wind turbine simulation could provide more true-to-scale aerodynamic loads than conventional methods. We will be refining the approach in the forthcoming wave tank at UPEI.
We have a new floating wind turbine design research project initiated, looking at new opportunities for cost savings in floating wind farms by shared support structure elements.
Another research area is mooring dynamics modelling — specifically, developing the MoorDyn model and using it for new applications. MoorDyn is available for stand-alone use and also is part of several existing offshore renewable energy simulation tools.
The second area of current research focus is in sustainable energy systems — studying at a higher level the combination of different energy sources along with energy needs, social stances, and environmental constraints that can inform decisions about what future opportunities for a more sustainable energy future could look like. This involves looking at energy resources and energy consumption, applying techno-economic optimization tools, and through collaboration factoring in aspects from other disciplines that play a role in determining the feasibility and success of different energy possibilities.
A recent paper in this area, co-authored with Dr. Andrew Swingler, is “Initial Perspective on a 100% Renewable Electricity Supply for Prince Edward Island,” in International Journal of Environmental Studies, 2017.
This is a listing of some previous research projects. Ongoing research is overviewed above.
My PhD research at UMaine, advised by Andrew Goupee, looked at combining simulations and experiments to better model floating wind turbines. I developed a real-time coupling of numerical and physical models, which can be used to provide a more versatile representation of aerodynamic forces when testing floating wind turbine designs at small scale in wave basins. In 1:50-scale tests, we demonstrated than an actuation system coupled with a real-time wind turbine simulation could provide more true-to-scale aerodynamic loads than conventional methods. My PhD thesis can be found here.
I created an efficient open-source dynamic mooring line model to fill the gap between free quasi-static models and sophisticated commercial dynamic models. MoorDyn is available for stand-alone use and also is part of several existing offshore renewable energy simulation tools. This is a topic of ongoing work. See the MoorDyn page for details.
This was a month-long testing campaign at Memorial University of Newfoundland lead by Scott Beatty. We tested a reconfigurable wave energy converter he developed in a variety of wave conditions, characterizing its hydrodynamics. The device used a linear actuator to emulate the power take off — an example of hybrid modelling in wave tank testing.
| Ocean Engineering paper |
My masters research at the University of Victoria, supervised by Curran Crawford and Brad Buckham, looked at several projects about floating wind turbines: support structure design optimization, floating platform optimization via basis functions, and mooring line modelling requirements. My MASc thesis can be found here. Information about the three masters projects is below.
The support structure (floating platform and mooring system) design problem is complicated by a number of competing objectives and an overwhelming number of design options. The wide range of platform configuration in particular makes searching for good designs using parameter studies and optimization techniques challenging — it’s hard to reduce the range of design possibilities down to a small number of parameters, and there are many discontinuities in the design space.
I created a support structure optimization framework to address these challenges. Using a 9-variable parameterization, a frequency-domain hydrodynamics model supplemented with linearized viscous drag terms, and a genetic algorithm optimizer, the framework spans a much larger extent of the design space than any previous optimization tools.
| OCEANS Paper |
I created a new genetic algorithm for the framework, one that can converge to multiple local optima and keeps a record of all evaluated design points in order to reduce the number of dynamics evaluations required for convergence. I call it a Cumulative Multi-Niching Genetic Algorithm (CMNGA). Details of its operation are available in the following paper, and I’ve created a rough Matlab implementation for sharing:
| IJARAI Paper | CMNGA in Matlab |
Traditional optimization approaches apply a number of assumptions in order to parameterize the geometry, and then perform repeated numerical simulations to find optimal combinations of design parameter values. I explored more generalized and intuitive approaches that are based more on performance principles than platform geometry, with the goal of exploring the design space more efficiently, methodically, and inclusively than the traditional approach. The easiest implementation, a “basis function” approach, proved to have some serious physical inconsistencies, but it may serve as a useful starting point for more sophisticated and physically-valid approaches.
| AIAA Paper | Renewable Energy Paper |
I carried out a comparison study of a quasi-static and a dynamic mooring line model. A quasi-static model, as used in NREL’s FAST code, ignores dynamic effects on the mooring lines including line momentum and hydrodynamic drag. I modified FAST, coupling its wind turbine and platform dynamics to ProteusDS, a highly-accurage dynamic mooring line model made by Dynamic Systems Analysis Ltd. This new capability allowed me to quantify the inaccuracies caused by the default quasi-static mooring model for different wind turbine designs and operating conditions.
| OCEANS Paper | Wind Energy Paper |