Abstract
The University of Alaska Fairbanks (UAF) conducted a study in the channel offshore Kotzebue during the summers of 2023 and 2024. Water speeds and other ocean water properties were measured to understand if ocean currents at this location are fast enough to be a source of renewable marine energy in the future.
Marine energy refers to technology that can extract power from moving water in oceans and rivers, including ocean waves, tidal currents, and river flow. This study was requested by the local utility, Kotzebue Electric Association (KEA). The work was done by the Pacific Marine Energy Center (PMEC) at the Alaska Center of Energy and Power (ACEP), which is a research center at UAF.
Both years, a mooring with oceanographic instruments was deployed on the seafloor in the channel for at least two months. In summer of 2023, the UAF mooring was placed in State of Alaska (SoA) waters near the Drake barge buoy. During the summer of 2024, the UAF mooring was located mid-channel in the City Tidelands near the hotel (Figure 1). We faced some challenges and damaged instruments as a result of sedimentation and debris that are common in Alaskan rivers.
Results include water speed and the direction the currents are flowing towards (Figure 4 and Figure 8). The results are presented as timeseries of 10 minute averages in 0.5 m depth increments (about every 1 ½ feet), so it is easy to see when and where the current speeds are faster. Velocity combines speed and direction and is shown in several different ways to help the reader visualize the currents in the channel (e.g., Figure 5 and Figure 12). Units for these variables are found in Table 3, with equivalent speeds in knots (nautical mile per hour).
The City Tidelands site in 2024 was deeper (14.5 m ≈50ft) and the channel was narrower than the mooring site in 2023, which had a water depth of 11.3 m (≈40 ft). Current speeds measured in the Kotzebue channel ranged from 0-1.75 m/s (0-3.14 knots), changing speed and flow direction towards the northeast (NE) or southwest (SW). Speeds were faster in the down-channel direction to the SW and in the surface waters, compared to the slower currents at the seafloor. These patterns are not surprising in this tidal system that is influenced by freshwater river inputs and local weather patterns.
This study did not evaluate potential environmental or social impacts or community response to marine energy development in Kotzebue. These would need to be addressed with local knowledge co-production before any marine energy development in Kotzebue because the channel is of key importance to the community for transportation and subsistence.