Abstract
To support the State of Washington’s marine spatial planning efforts, the Pacific Northwest National Laboratory (PNNL) and Parametrix were asked to conduct a spatial analysis of basic siting factors to determine where marine renewable energy development may be feasible on the Washington coast. The scope of the study includes tidal, wave, and offshore wind power generating technologies. The devices we selected to represent these technologies are the core device types anticipated to be commercially-viable in the Pacific Northwest. The scope includes projects that would commence a planning or feasibility phase within the next five to seven years. This time horizon serves to narrow the focus to existing, tested technologies deployed within a few miles of shore, with the exception of offshore wind floating platform technology which would most likely be deployed within 20 miles of shore.
This study uses a multi-criteria decision analysis framework of weighted additive algorithms to evaluate site suitability. Attributes of suitability used in this analysis represent fundamental economic and technical feasibility considerations and include energy potential, water depth, proximity to shore, ports, and transmission infrastructure. Socioeconomic, legal, regulatory, national security, and environmental factors—key factors to consider in planning for renewable energy development—are beyond the scope of this study. The separation of fundamental suitability factors from other considerations influencing marine spatial planning is intentional and intended to respect Washington State’s stakeholder-informed planning process.
We developed conceptual models to organize attributes of suitability. Eight models were needed to represent the breadth of existing ocean energy generation devices suitable for Washington coast deployment. Available literature and expert advisors familiar with the industry, technologies, and devices informed the application of scores and weights to attributes for each model. Additive algorithms enabled a numerical translation of composite suitability that could then be represented spatially in a geographic information system. At the same time, we developed a geospatial database for the Washington coast containing available geospatial datasets corresponding to attribute suitability and based on Bureau of Ocean Energy Management’s (BOEM) Outer Continental Shelf (OCS) leasing blocks. The dataset divides each BOEM block into sixteen, 1.44 square kilometer (0.56 square mile [mi2]) sections, for a total of 24,291 units (referred to as aliquots). These are the minimum units for this analysis, and are what is referred to as sites within this report. Multiple sites comprise areas of suitability.
The results of this analysis are represented in a series of eight maps depicting suitability for tidal, wave, and offshore wind devices. Results suggest that there is a wider range of sites with higher suitability scores off the southern half of the Washington coast than the northern coast, although results differ based on device type. Fixed foundation wind energy models and nearshore wave device models closely followed this pattern, though it is less distinct in the mid- and deepwater wave model results. Most areas with high suitability occur within 25 miles or less of the coast. Results also suggest that the Washington coast has limited areas suitable for tidal energy development.
This study provides the base data layer—siting suitability based on technical and economic attributes—needed to inform planning for this potential new use of Washington coastal waters. The data identify areas meeting basic feasibility requirements for ocean energy that, if developed, may create conflict with existing uses. The results of this study are in no way intended to serve as a recommendation for project siting. Rather, these results are designed to inform a comprehensive marine spatial planning process that considers existing and future ocean uses against local and regional priorities.
This suitability analysis approach was first developed by Oregon Wave Energy Trust and Parametrix to evaluate wave energy development off the Oregon coast (OWET 2009, 2010).