Across the world’s coasts, engineers are turning the steady pulse of tides and the persistent motion of ocean waves into a new class of renewable power. Unlike wind and solar, the lunar clock governing tides is predictable decades in advance, and wave fields can be forecast days ahead, creating a resource that complements variable generation. From fast tidal streams in narrow channels to long-period swells rolling ashore, these technologies promise low-carbon electricity close to population centers that already cluster along coastlines. After years of prototypes, grid-connected pilots are now proving survivability, refining designs, and building the operational know-how needed to scale. The result is an emerging toolkit that can strengthen coastal energy systems, reduce diesel dependence on islands, and add resilience to decarbonizing grids.
Tidal and wave energy are relevant now because the global energy transition needs clean power that is both reliable and geographically diverse. Coastal regions host significant demand and often face grid constraints, making local generation particularly valuable. The predictability of tides and the smoother, delayed response of waves to passing weather systems can help balance wind- and solar-heavy portfolios. In a world seeking to electrify heat, transport, and industry, firming resources anchored in physical cycles add confidence to planning and operations.
The physics underpinning these resources drives their value. Tides arise from the gravitational pull of the Moon and Sun acting on ocean basins, creating currents that ebb and flow in patterns known and charted well in advance. Wave energy is generated when winds transfer momentum to the sea surface, and the resulting swells often travel far from weather systems, making them forecastable on multi-day horizons. This means dispatchers can schedule maintenance and anticipate output with unusual precision for a renewable source.
It also means tides and waves frequently peak at different times than local wind or solar, smoothing aggregate generation. Multiple technology pathways are maturing in parallel. Tidal stream turbines, which resemble underwater wind turbines, harvest kinetic energy from fast currents in straits and headlands; designs include axial-flow rotors, cross-flow rotors, and floating platforms anchored by moorings. Tidal range systems, such as barrages and lagoons with sluices and turbines, exploit the rise and fall of sea levels across impoundments.
Wave energy converters span point absorbers that bob with the surface, oscillating water columns that drive air through turbines, attenuators aligned with wave direction, overtopping devices, and nearshore surge flaps. Each approach trades off efficiency, survivability, maintenance access, and site suitability, prompting a diversity of solutions rather than a single winner. A series of real-world deployments demonstrates both potential and progress. Historic tidal range plants like La Rance in France and the Sihwa Lake station in South Korea have generated for years, showing durability at utility scale.
In tidal stream, the MeyGen project in Scotland’s Pentland Firth has exported tens of gigawatt-hours, and the 2 MW O2 turbine from Orbital Marine Power has been producing at the European Marine Energy Centre (EMEC) in Orkney. Nova Innovation’s array in Shetland has incrementally added turbines since 2016, refining modular installation and operations. For waves, grid-connected pilots and test sites such as EMEC in Scotland, the U.S. Navy’s Wave Energy Test Site in Hawaii, and Portugal’s nearshore deployments are providing performance data under controlled conditions.
Engineering lessons from early arrays are closing practical gaps that once limited scale. Devices now emphasize tow-to-port maintenance and quick-connect electrical umbilicals to reduce costly offshore interventions. Designers tackle saltwater corrosion and biofouling with improved materials, coatings, and modular components that can be swapped rapidly in weather windows. Numerical models and digital twins are calibrated with field data to optimize moorings, control strategies, and fatigue life.
These advances draw on established offshore wind and oil-and-gas supply chains, accelerating learning and standardization. Economics are moving in the right direction as fleets accumulate operating hours and policy support targets pre-commercial arrays. Tidal stream projects report capacity factors often in the 30–40% range at energetic sites, and cost reductions are expected as manufacturing scales and installation cycles shorten. Recognizing the system value of predictability, several governments have created tailored mechanisms, such as the United Kingdom’s ringfenced auctions for tidal stream within its Contracts for Difference program, alongside European, U.S., and Canadian research funding.
The complementarity with wind and solar can reduce curtailment and lower balancing costs, and some projects have paired tidal generation with electrolyzers to produce hydrogen where grid capacity is limited. Islands and remote microgrids, which currently rely on imported diesel, are among the earliest markets where avoided fuel costs can justify deployments. Development must proceed with careful attention to environmental and community context. Monitoring programs have so far observed limited interactions between tidal turbines and marine mammals or fish at tested sites, but results are site-specific and require continued study, especially as arrays scale.
Installation and cabling can disturb seabed habitats, and developers are refining methods to minimize noise, sediment resuspension, and electromagnetic exposure. Because devices are mostly submerged and compact, visual impacts are generally low compared to onshore infrastructure, yet fishing, shipping, and recreation need to be accommodated through maritime spatial planning. Collaborating with local stakeholders early helps identify shared-use opportunities, including co-location with aquaculture or artificial reef benefits from foundations. Taken together, these technologies are carving out a role as dependable contributors to coastal energy systems rather than stand-alone silver bullets.
Their strength lies in predictability, proximity to load, and the ability to complement faster-growing renewables, especially in regions with strong currents or persistent swell. As more devices operate through full seasonal cycles, bankable performance datasets will reduce financing risk and attract private capital. The trajectory resembles the early years of offshore wind: steady iteration, shared learnings at test centers, and policy frameworks that reward delivery and durability. The next decade will likely hinge on getting from single devices to multi-machine arrays that standardize components, contracts, and maintenance playbooks.
Clear permitting pathways, robust environmental baselines, and transparent data sharing will build public confidence and cut lead times. Investments in ports, vessels, and export cables will lower logistics costs while creating skilled coastal jobs. If these pieces align, tidal and wave energy can become a quiet workhorse of decarbonization—predictable, local, and resilient—helping coastal communities power their futures from the motion of the sea.
