Researchers have cataloged 426 potential tidal-stream turbine sites spread across 19 countries, quantifying a theoretical energy resource of 1,000 terawatt-hours per year from 262 of those locations. The finding arrives as the U.S. Department of Energy commits $45 million to advance tidal and current energy technology, and as Scotland’s MeyGen tidal array continues to operate in open water. Together, the science and the funding highlight growing interest in underwater power generation, even as most projects remain at the pilot and early-commercial stage.
A Global Atlas of Tidal Energy Hotspots
The review, published in Renewable and Sustainable Energy Reviews and hosted by the Oxford network, represents the most detailed global inventory of tidal-stream resources assembled to date. By analyzing decades of oceanographic measurements, the authors screened coastlines worldwide and identified 426 candidate sites where tidal currents are strong and consistent enough to spin submerged turbines. Of the 262 sites for which the team could estimate energy yield, the aggregate theoretical output reached 1,000 TWh per year, a figure that underscores the scale of the theoretical resource if it could be harnessed.
What makes the study different from earlier resource surveys is its breadth. Previous assessments tended to focus on a single country or strait. This review stitches together data from 19 nations, creating a comparative framework that lets planners weigh, say, Alaska’s Cook Inlet against Scotland’s Pentland Firth or channels off the coast of South Korea. That cross-border view matters because tidal energy developers have historically clustered in a handful of European locations, potentially overlooking high-yield sites in North America, East Asia, and the Southern Hemisphere.
The atlas also emphasizes that not every energetic channel is equally suitable. Depth, seabed composition, proximity to grid infrastructure, and competing uses such as shipping all influence whether a promising current can host turbines. By ranking sites on multiple criteria instead of just peak flow speed, the authors aim to steer limited development capital toward locations where projects are most likely to succeed technically, economically, and environmentally.
U.S. Government Bets $45 Million on Tidal Power
Washington is acting on the premise that the United States holds significant untapped tidal resources. The Department of Energy announced a $45 million opportunity (DE-FOA-0002845) structured around two topic areas: building a pilot demonstration site and supporting community-led planning for tidal projects. The dual focus reflects a lesson from onshore wind and solar development, where community opposition can stall projects even when the engineering is sound. By funding local engagement alongside hardware, the DOE is trying to clear social and regulatory hurdles before they calcify.
The federal investment builds on years of geospatial groundwork. Oak Ridge National Laboratory developed a national geodatabase of tidal-stream power using ROMS ocean modeling calibrated against real-world measurements, defining hotspot criteria based on power density thresholds, minimum area, and depth. The Bureau of Ocean Energy Management maintains GIS layers that let developers overlay tidal resource data with shipping lanes, protected habitats, and existing infrastructure. The National Renewable Energy Laboratory offers its own Marine Energy Atlas for further site screening. These tools collectively narrow the search from thousands of miles of coastline to a manageable set of high-priority zones.
The DOE has also awarded grants to advance specific tidal projects. Nate Johnson, a development executive at ORPC, is among the industry figures whose work has benefited from federal support aimed at enabling tidal energy studies and early deployments. Those grants fund everything from environmental monitoring to grid-integration analysis, helping small companies bridge the gap between prototype devices and bankable projects.
Scotland’s MeyGen Proves the Technology Works
While the United States maps sites and funds pilots, Scotland already has a working tidal array generating electricity. The MeyGen project in the Pentland Firth has been running continuously since 2018 with four 1.5-megawatt tidal turbines anchored to the seabed. That track record, now spanning several years, provides the closest thing the industry has to a proof of concept at meaningful scale. Each turbine captures energy from tidal flows that rush between mainland Scotland and the Orkney Islands, delivering predictable output twice daily in a pattern that grid operators can forecast months in advance.
This predictability is what separates tidal energy from wind and solar. A solar farm’s output drops to zero at night, and wind turbines idle during calm weather. Tidal currents, driven by gravitational forces, follow schedules that can be calculated centuries ahead. For grid planners trying to balance intermittent renewables, a highly predictable source with no direct operational emissions can be a compelling addition, even if costs remain higher than more mature renewables today.
MeyGen has also helped refine the nuts and bolts of tidal engineering. Developers have learned how to install and retrieve heavy nacelles in rough seas, manage biofouling on underwater components, and operate power electronics that must function reliably in a corrosive, high-pressure environment. Those lessons feed directly into the design of next-generation turbines and inform permitting discussions in other countries that can point to a functioning project rather than a theoretical model.
Collision Data So Far Shows No Recorded Incidents
One of the persistent concerns about submerged turbines is the risk they pose to marine mammals. Seals, porpoises, and dolphins share the fast-flowing channels where tidal devices operate. Yet monitoring data from UK installations tells a reassuring story. A technical review hosted by the Tethys database found no recorded marine mammal collisions across the UK tidal sites covered in its case studies. Animals appear to detect and avoid the slow-turning rotors, though researchers caution that data collection is still limited and larger arrays will need continued surveillance.
The absence of collisions so far challenges a common assumption that has slowed permitting. Environmental reviews for tidal projects often require years of baseline wildlife surveys before a single turbine can be installed. If the collision risk proves as low as early evidence suggests, regulators may be able to revisit monitoring and permitting requirements over time. Any changes would depend on site-specific conditions and continued data collection, but developers say shorter timelines could materially reduce project costs.
Developers are also experimenting with additional safeguards, including acoustic deterrents, real-time monitoring cameras, and operational curtailment during sensitive periods. These measures, combined with accumulating empirical data, may allow regulators to move from precautionary bans toward adaptive management that allows projects while watching closely for impacts.
From Small Demos to Commercial Scale
The marine energy sector now faces a familiar challenge: moving from one-off demonstration projects to standardized, bankable assets. Early devices were often bespoke machines tailored to a specific site. To compete with mature renewables, tidal developers must cut costs through repetition, modular designs, and supply chains that can deliver multiple units per year.
Arrays like MeyGen point the way by clustering turbines to share subsea cables and onshore grid connections. Future projects envisioned under the DOE funding call would follow a similar pattern, using a limited number of machines to validate performance, then scaling up if results match expectations. As more arrays connect to the grid, financiers gain the operational data they need to price risk, lowering the cost of capital that currently inflates tidal power prices.
Policy support will be critical during this transition. Long-term power purchase agreements, targeted tax credits, and dedicated seabed leasing rounds can all help early projects clear the valley between prototype and commercial maturity. At the same time, planners must integrate tidal arrays into broader coastal strategies, balancing them with fisheries, conservation zones, and shipping corridors. The detailed resource mapping now available gives governments and communities a clearer basis for those trade-offs.
If the global atlas of tidal hotspots, the U.S. funding surge, and Scotland’s operational array share a common message, it is that the physics of tidal power are no longer in doubt. The remaining questions revolve around cost, scale, and coexistence with marine ecosystems and coastal communities. With careful planning and sustained investment, underwater turbines could evolve from niche experiments into a dependable pillar of low-carbon electricity systems in some of the world’s most energetic seas.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
