Planning for Effects of Wave Energy Development Before Going to Sea

Submitted by Kelly Ruehl, Chris Chartrand, and Jesse Roberts on Feb 23, 2015

As interest has grown in developing a range of low carbon renewables, harnessing the vast energy from ocean waves has become desirable. Although few arrays of wave energy converters (WECs) have been deployed worldwide, planning for wave farms requires that we understand the maximum amount of energy that can be extracted from waves, while ensuring that environmental responsibilities are met. Numerical models allow us to simulate arrangements of WECs to minimize harm to the environment, while optimizing the production of power, without incurring the enormous costs of deploying WECs in coastal waters. These efforts to develop useful computer tools include the modified SWAN model (Simulating Waves Nearshore) that has been produced by researchers at Sandia National Laboratories.

A New Tool - The Department of Energy and Sandia National Laboratories are pleased to announce the public release of SNL-SWAN v1.0 (Sandia National Laboratories – Simulating WAves Nearshore).  This tool is a result of a multi-year research study to accurately simulate altered wave propagation due to the operation of WEC arrays. SNL-SWAN is an open source code for wave energy converter (WEC) array simulation, based on modifications to the open source spectral wave model, SWAN (Simulating WAves Nearshore), developed by TU Delft. By including a WEC module in SWAN, researchers can account for power performance of WECs, the effects on the wave field, and the potential effects on the environment such as changes in water flow, altered sediment transport, and bottom scour. The changes to SWAN rely on the wave height at each WEC and/or the wave period-dependent power absorption.

SNL-SWAN has been developed to assist the marine hydrokinetic (MHK) industry in assuring that environmental effects are minimized in planning for array development. A user’s manual has been written to allow developers, regulators, researchers, and other interested parties to easily apply SNL-SWAN to WEC arrays.

More Details on SNL-SWAN - SNL-SWAN includes a WEC module that accounts for the frequency and sea state-dependent nature of wave energy extraction. By more accurately modeling the energy removed by WEC devices, greater confidence can be given to the numerically observed changes in wave propagation and associated environmental effects due to the presence of wave energy farms. Results from SNL-SWAN can also be incorporated into circulation models, such as SNL-EFDC or Delft-3D, to study a wave farm’s potential impact on coastal circulation patterns and sediment transport.  Findings from these types of numerical studies can be used to provide siting guidance for developers and provide regulators with information needed to make timely and accurate permitting decisions. For references on the development and application of SNL-SWAN, please refer to the Sandia National Laboratories SNL-SWAN webpage.

Downloading the Code - SNL-SWAN Version 1.0 code and the user’s manual are available for download on GitHub. You will find compiled executable versions of SNL-SWAN for Windows and Linux, as well as the SNL-SWAN source code.

For More Information – You can learn more about the project, from the Sandia National Laboratories SNL-SWAN webpage, or by contacting Kelley Ruehl or Chris Chartrand for questions about SNL-SWAN code development, and Jesse Roberts for questions about SNL-SWAN application for environmental effects studies.

Wave Energy