1. Marine Renewable Energy
Sediment Stability Evaluation
Craig Jones and Grace Chang
Integral Consulting Inc.
cjones@integral-corp.com; gchang@integral-corp.com
Jesse Roberts, Kelley Ruehl, and Chris Chartrand
Sandia National Laboratories
jdrober@sandia.gov; kmruehl@sandia.gov; ccchart@sandia.gov
2. Introduction
• Marine and Hydrokinetic (MHK) arrays have the
potential to alter the physical environment
o Sediment transport
o Ecological processes
o Socioeconomic services
3. Objectives
• Validate a modified version of
the wave modeling tool, SWAN
• Simulate wave propagation
through hypothetical WEC arrays
• Evaluate change in the coastal
system
• Demonstrate a Seabed
Evaluation Framework
Pacific Energy Ventures (WET-NZ)
4. • WEC energy absorption varies
over frequency
• User-specified power matrix for
WEC devices
• SNL-SWAN calculates frequency
dependent transmission
coefficient associated with
specific WECs
SNL-SWAN
Babarit, A., J. Hals, M.J. Muliawan, A. Kurniawan, T. Moan, and J.
Krokstad (2012) Numerical benchmarking study of a selection of wave
energy converters, Renew. Energ., 41, 44-63.
Smith, H., C. Pearce, D. Millar (2012) Further analysis of change in
nearshore wave climate due to an offshore wave
farm: An enhanced case study for the Wave Hub site, Renew.
Energ., 40, 51-64.
5. Model Investigation
• Monterey Bay to Santa
Cruz, California
• Nested model domain
— Monterey Bay: 100 m grid
resolution
— Santa Cruz: 10 - 20 m
grid resolution
• Validated with measured
data
— Monterey Bay: NOAA
NDBC buoy
— Santa Cruz: Datawell
Waverider
6. SNL-SWAN: Model Set-Up
• Results evaluated near-shore Santa Cruz
• Model simulations with WECs compared to simulations
without WECs (baseline)
7. SNL-SWAN: Results
9.5 m oscillating flap 20 m two-body heave
26 m heave
50 m oscillating
water column
8. Modeling Wave Driven Circulation
Hydrodynamics Model
• The SNL-EFDC three-
dimensional, hydrostatic, free
surface, hydrodynamic model
Incorporation of Wave Effects
• Wave generated radiation shear
stresses are incorporated into
momentum equations
• The wave dissipation is a
source term in the turbulent
transport equations
9. Hydrodynamic Model Validation
• A 10 km by 10 km
domain was used
• A nearshore ADCP
was used to measure
currents
• Drifter studies were
used to compare
nearshore circulation
11. Seabed Assessment
• Bathymetry, modeled waves
and currents, and seabed
characteristics integrated
into a classification system
• A scoring criteria defines the
risk to offshore environment
due to seabed stability
alterations
• How big is the change?
12. Sediment Mobility Validation
• Spatial maps of sediment
mobility can be compared
with high resolution
surveys
• The results have
excellent spatial
consistency
13. Example Evaluation
• Plots of stability change can be made to evaluate
impacts on the local environment
Location of MHK array
14. Summary
• Robust model frameworks used to develop enhanced tools
• Quantitative methods used to evaluate the effects of MHK
arrays in coastal regions
• Small arrays (~10) of WEC devices have minimal effect on the
physical environment
• Further site specific evaluation in regions where arrays are
installed will help to validate and streamline tools and
techniques
15. • Sandia National Laboratories
— Wind and Water Power Technologies Office
• U.S. Department of Energy
— Wind and Water Power Technologies Office
• CEROS – U.S. Navy
Craig Jones: cjones@integral-corp.com
Jesse Roberts: jdrober@sandia.gov
Acknowledgments
