We are focused on various aspects of designing and optimizing MHK energy systems. In the area of wave energy conversion, we are interested in the optimal design and operation of arrays of wave energy converters (WECs), or wave farms. In the area of river and tidal energy systems, we study how energy flows through rivers and tides, with the aim of harvesting this energy.

 

Visit the Publications page for research publications on these topics.

 

 

Ocean Wave Energy Farms

Wave Farm

RESOURCE MODELING

Wave farm operations and grid interactions require accurate power-output forecasts that account for site-specific future wave conditions, hydrodynamic interactions among WECs, and WEC geometry. We are developing models and methods for mproving both short- and long-term forecasts of ocean conditions; and using these predictions, array geometry, and power-take off dynamics to provide reliable calculations of wave farm output power.

 

LAYOUT DESIGN

The locations of WECs within a wave farm can have a significant impact on the total power of the farm due to the hydrodynamic interactions among the WECs. The total power is a nonconvex function of the WEC locations, and it has been observed that a wave farm optimized for a particular wave environment tends to perform quite poorly when the environment changes just a little. We use optimization models and algorithms to deliver more robust solutions to wave farm layout.

SENSOR NETWORK DESIGN

We are studying the types and locations of sensors that should be placed near wave farms to collect data on wave characteristics and forecast the actual waveforms at the WECs, thus improving the control of the WECs. To deal with noisy sensor measurements, we have developed optimization models and algorithms for maximum-likelihood estimation of wave realizations as a function of sensor system design, and we have looked to optimize the design itself with respect to the types and locations of sensors. In addition, we are developing rapid fault detection tests that use wave sensor data to assess system state and conduct hypothesis tests to identify system faults.

OUTPUT POWER CONTROL

We are developing algorithms for simultaneous control of multiple WECs within a wave farm. Our models account for and exploit both the spatial-temporal variations in the ocean environment and the hydrodynamic coupling between the WECs. Additionally, we are developing predictive control methods using short-term forecasts enabled by wave sensors in and around the farm. Specific control strategies of interest include modifying damping coefficients of WECs and using storage to stabilize the farm’s power output to enhance grid stability and reduce CO2 emissions due to ramping of conventional generators.

MARKETS AND EMISSIONS

We are studying reliable integration of wave farms into deregulated electricity markets and quantifying reductions in CO2 emissions enabled by wave power due to reduction of both fossil-fuel-based generation and compensatory ramping of conventional generators required by more volatile forms of renewable energy. We explore market opportunities enabled by the predictability of waves and study optimal market interactions for wave power producers.

SYSTEM-LEVEL CYBER-ARCHITECTURE

We are designing a cyber control system to coordinate the various components (WEC hydrodynamics, multi-WEC control, storage control, forecasting techniques, etc.) of the wave farm. Our goal is to develop a multi-agent system model that combines symbolic and numeric reasoning with learning capabilities. We will combine these components with ontological information that models entities and interactions of WEC operations.

River and Tidal Energy Systems

Wave Farm

Design optimization and non-linear fluid structure interactions of Marine Current Turbines

Our goal is to develop, test and validate computational models that describe the non-linear dynamics of fluid-structure interactions (FSI) for hydrokinetic energy (HKE) systems. A design optimization (using gradient-based techniques) of decoupled hydrodynamics and structural mechanics solvers would be inefficient and would likely lead to a locally optimal solution. Instead, we are developing an algorithm that, when coupled with the FSI solver, will lead to convergence on a globally optimal solution.

Hydrodynamic and Hydrological Impacts of HKE Systems

We experimentally study the three-way coupling among the hydrokinetic energy harvesting device, the approach flow and the local bed topography. We are also investigating the overall impact of the energy harvesting device on river morphology (scour development), flood conveyance and sediment transport due to local extraction of kinetic energy from the stream and the induced non-homogeneous turbulent stream. The change in the local topography can substantially increase the dynamic interplay between the approach flow and the turbine in ways that are currently completely unknown.

Hydrokinetic Farm Layout

We are also exploring HKE array configurations to quantify the effects of increased turbulence from various sources, including free-stream turbulence, upstream hydrokinetic devices (arrays) and in-stream structures like bridge piers. We are developing engineering models for calculating production losses and enhanced blade loading (leading to fatigue) due to wake effects from upstream or neighboring MCTs, based on momentum principles that are applied to each individual rotor unit.