Modeling Sea Ice Effects for Wave Energy Resource Assessments

Abstract

Wave-generated power has potential as a valuable coastal resource, but the wave climate needs to be mapped for feasibility before wave energy converters are installed. Numerical models are used for wave resource assessments to quantify the amount of available power and its seasonality. Alaska is the U.S. state with the longest coastline and has extensive wave resources, but it is affected by seasonal sea ice that dampens the wave energy and the full extent of this dampening is unknown. To accurately characterize the wave resource in regions that experience seasonal sea ice, coastal wave models must account for these effects. The aim of this study is to determine how the dampening effects of sea ice change wave energy resource assessments in the nearshore. Here, we show that by combining high-resolution sea ice imagery with a sea ice/wave dampening parameterization in an unstructured grid, the Simulating Waves Nearshore (SWAN) model improves wave height predictions and demonstrates the extent to which wave power decreases when sea ice is present. The sea ice parametrization decreases the bias and root mean square errors of wave height comparisons with two wave buoys and predicts a decrease in the wave power of up to 100 kW/m in areas around Prince William Sound, Alaska. The magnitude of the improvement of the model/buoy comparison depends on the coefficients used to parameterize the wave–ice interaction.

Marine renewable energy for Arctic observations

“…The wave energy resources vary seasonally and with ice cover, but the Bering Sea has potential for wave energy converter usage during nine months of the year. The wave model used in this analysis did consider sea ice cover, but the physics of the dampening of waves by sea ice is not well understood and is the topic of current research (Branch et al, 2021). The relative velocity between sea ice and the water below can be considered a marine renewable energy resource if a hole can be drilled in the ice and a turbine or VIV instrument can be lowered into the water through it.…”

Increasing coastal exposure to extreme wave events in the Alaskan Arctic as the open water season expands

“…The ADCIRC + SWAN (ADvanced CIRCulation + Simulating WAves Nearshore) coupled model is used for numerical simulations of astronomical tides, storm surge 58,59 , and waves 60 as a function of forcing fields: wind, pressure, and sea ice concentration. Individually, both models have been used within the Alaska region to simulate water levels 61,62 and waves 35,63,64 . Through recent model developments, existing sea ice parameterizations for both storm surge 61 and wave dissipation 8 have been implemented into the coupled model.…”

“…Within SWAN, wave dissipation through ice fields is represented by the parameterization commonly known as IC4M2 66 which has recently been added into the model 8 . This parameterization has been utilized within Alaska and has shown reasonable performance in modeling wave attenuation by sea ice under a variety of scales, seasons, and sea ice conditions 35,63 . For this simulation, accounting for the expansive domain and assumed variety of sea ice conditions, we default to utilizing the coefficients derived by Meylan et al 66 for use with IC4M2.…”