It is estimated that Cook Inlet contains about a third of the potential tidal energy of the United States, a resource that could provide roughly 15 times the entire Railbelt’s annual electricity consumption.
It’s never been a secret that tides in the Forelands region – the 10-mile bottleneck where Cook Inlet squeezes between the Kenai and Kustatan Peninsulas – are full of energy. Drift netters know it, and so does the National Renewable Energy Laboratory (NREL). In 2021, NREL estimated that Cook Inlet contains about a third of the potential tidal energy of the United States, a resource that could provide roughly 15 times the entire Railbelt’s annual electricity consumption.
New research is bringing sharper focus to how much of that energy we could practically use. An NREL study released in April modeled tidal deployment alongside wind, solar, and storage projects currently under feasibility study and set to be completed by 2035. They found that today’s limited Railbelt transmission system is a barrier to tidal energy reaching its potential scale.
Currently, only a single, low-capacity transmission line connects the Peninsula to the rest of the Railbelt, and most of its capacity is dedicated to power from the Bradley Lake dam. With this constraint in place, 200 megawatts would be the practical limit on tidal generation – still enough on average to meet HEA’s peak demand. Expanding HEA’s battery system (as the co-op is currently planning) or doubling the transmission capacity of the powerline off the Peninsula (as the Alaska Energy Authority is planning) could raise the practical capacity of tidal to 300 MW. With sufficient transmission and mature tidal technology, NREL found tidal has the potential to significantly displace gas as a predictable (though still variable) resource to balance the unpredictable variability of wind and solar.
The technology, though, is far from mature. NREL’s study didn’t look at how the tides could be harnessed — it just assumed a megawatt-scale tidal generator would be commercially available by 2035. As of today, tidal is a nascent, underfunded technology struggling to get off the drawing board. A start-up tidal developer called Ocean Renewable Power Corporation (ORPC) received federal preliminary permits for a project in the Forelands over a decade ago, but struggled to compete with state-subsidized natural gas. Now with an uncertain gas supply, ORPC has received $3 million from the U.S. Department of Energy for planning, engineering, and permitting what it’s calling “The American Tidal Energy Project” at the Forelands. In March 2025, ORPC will have the chance to win a further $29 million from Dept of Energy to reach the goal of having 5 megawatts of tidal generation in the water by 2028. If that energy can be competitively priced, the tide may have turned.
ORPC will be the developer and planner of the project (including negotiating power sales with HEA), but it won’t have the only machines in the water. Two other tidal start-ups, with technology very different from ORPC’s TidGen device, are partners in the project. Aquantis suspends its turbine near the surface of the water from the underside of a floating buoy, while Verdant’s windmill-like devices sit on the bottom, and ORPC’s TidGen floats in the middle of the water column. With so many practical questions about how tidal generators will function in Cook Inlet’s silty, icey, hazardous waters, having a diversity of devices working at different depths is one of the project’s strengths.
Like many energy stories, the history of tidal power in Cook Inlet has been slow, twisting, and full of false starts. But slack tide may be past—and the flood is coming in.