Abstract
This report presents the findings of a case study that evaluates the impact of integrating significant tidal energy generation in the Cook Inlet in Alaska. The case study is part of a series within the “Quantifying the Grid Value of MRE [Marine Renewable Energy] in Early U.S. Markets” project funded by the U.S. Department of Energy (DOE). 1 The Cook Inlet represents approximately 30% of the total tidal energy in the United States. It is located alongside the Kenai Peninsula, a region serviced by the Homer Electric Association (HEA). HEA constitutes the southernmost portion of Alaska’s Railbelt electricity grid, which in its entirety serves approximately 75% of the state’s population and stretches across southcentral Alaska from Homer in the south to Fairbanks in the north. The Railbelt utilities sold 4,408 gigawatt-hours (GWh) of electricity in 2020, and HEA’s sales were 11% of that (496 GWh). Despite significant natural resources, Alaska is among the states with the highest energy prices. Increasing renewable energy in the region has been proposed to address these high prices. Because of the substantial and highly predictable tidal flow rate in the inlet, along with its proximity to the majority of Alaska’s population, tidal energy generation has been proposed; however, there have been no studies to date that evaluate its potential as part of a mixed energy portfolio from a grid integration perspective. This study takes a scenario-based approach to evaluate the tidal energy potential in the Cook Inlet, in which 100–500 megawatts (MW) of tidal energy are integrated into the grid under different infrastructure scenarios. These scenarios include increased energy storage and transmission line upgrades, a “Basecase” scenario with no additional upgrades, and a reference case with no tidal energy. The project team worked with HEA to develop a model of the entire Railbelt grid in the pricemaker production cost modeling software PLEXOS by Energy Exemplar.2 The final model closely aligns with the utility’s models. The model simulates 2035 by scaling load and adding new wind, solar photovoltaic (PV), and battery storage plants already undergoing feasibility studies. Table ES-1 lists the plants included at the time of modeling in November 2022. Because of scheduling and review conflicts associated with the DOE Funding Opportunity Announcement for U.S. Tidal Energy Advancement (DE-FOA-0002845), the publication of this report was delayed, and some of these assumptions may require updating in any subsequent modeling and analysis.