title: "Tidal and Wave Energy" description: How the ocean's tides and waves could generate clean electricity — the technology, current projects, potential, and challenges facing marine energy in America. summary: How the ocean's tides and waves could generate clean electricity — the technology, current projects, potential, and challenges facing marine energy in America. category: hydro difficulty: Advanced updated: 2026-02-10 tags: ["tidal", "wave energy", "marine energy", "ocean power", "renewable energy", "emerging technology"] relatedTools: [] faqs:
- question: How much electricity could ocean energy provide? answer: DOE estimates the technical potential of wave energy along U.S. coastlines at roughly 1,400 TWh/year — about one-third of current U.S. electricity consumption. Tidal energy potential is smaller but significant in specific locations with strong tidal currents. However, only a fraction of this technical potential is practically and economically recoverable.
- question: Does the U.S. have any operating tidal or wave power plants? answer: No utility-scale tidal or wave power plants operate in the U.S. as of early 2026. Several pilot projects have been tested — notably at the PacWave test site off the Oregon coast and small tidal projects in Maine and Alaska. The technology is at a much earlier stage than wind or solar, comparable to where wind power was in the 1980s-90s.
- question: Why is ocean energy so far behind wind and solar? answer: The ocean is an extremely harsh environment — saltwater corrosion, storms, biofouling (marine growth on equipment), and the difficulty of installation and maintenance at sea. Engineering devices to survive 25+ years in open ocean while remaining cost-effective is immensely challenging. The resource is also diffuse compared to a concentrated wind stream or solar irradiance.
- question: What countries lead in ocean energy? answer: The UK leads in tidal stream (MeyGen project in Scotland — the world's largest tidal array), and several European countries have active wave energy test centers. France operates the La Rance tidal barrage (240 MW, operating since 1966). South Korea built the Sihwa Lake tidal barrage (254 MW). China and Australia also have active programs.
Tidal and Wave Energy
The ocean contains enormous energy — from the predictable rhythm of tides to the relentless motion of waves. Marine energy is the least developed major renewable resource, but it offers something unique: predictability (tides) and consistency (waves) that complement solar and wind.
Tidal Energy
How Tides Work as Energy
Tides result from the gravitational pull of the moon and sun on Earth's oceans. Unlike wind and solar, tidal energy is:
- Perfectly predictable — tidal patterns are known decades in advance
- Regular — two high and two low tides per day (approximately)
- High density — water is 832x denser than air, so a slow tidal current carries far more energy than wind at the same speed
Tidal Energy Technologies
Tidal Barrage:
- A dam-like structure across a tidal estuary or bay
- Water flows through turbines as the tide rises and falls
- Proven technology (La Rance, France, operating since 1966 at 240 MW)
- Very high capital cost and significant environmental disruption (blocks estuary)
- No tidal barrages in the U.S.; none currently planned
Tidal Stream (Tidal Current) Turbines:
- Underwater turbines placed in fast-flowing tidal channels
- Similar concept to wind turbines but smaller and underwater
- Most actively developed technology for new projects
- Leading example: MeyGen project (Scotland) — 6 MW operational, expanding to 80+ MW
Tidal Lagoon:
- Artificial enclosed area on the coast that fills and empties with tides
- Less disruptive than barrages but unproven at scale
- Swansea Bay (UK) proposal was studied extensively but not built due to costs
U.S. Tidal Resources
The best U.S. tidal energy sites have strong, concentrated tidal currents:
| Location | Resource Quality | Status | |----------|:-:|---------| | Cook Inlet, Alaska | Excellent — tidal range up to 12 meters | Pilot testing (ORPC) | | Puget Sound, Washington | Good — strong currents in narrow passages | Resource assessed | | Maine coast (Cobscook Bay) | Moderate | Small pilot tested | | San Francisco Bay | Moderate — strong but complex currents | Resource assessed | | New York East River | Moderate | Verdant Power pilot tested (2006-2009) |
Alaska has by far the strongest tidal resources in the U.S.
Wave Energy
How Waves Carry Energy
Wind blowing across the ocean surface transfers energy to waves. Waves can travel thousands of miles with minimal energy loss, carrying concentrated energy from distant storms to coastlines.
Wave energy is measured in kilowatts per meter of wave front (kW/m):
- North Atlantic/Pacific: 30-60 kW/m
- U.S. West Coast: 20-40 kW/m
- U.S. East Coast: 10-20 kW/m
- Hawaii: 15-25 kW/m
Wave Energy Technologies
No single dominant design has emerged. Major concepts include:
| Type | How It Works | Example | |------|-------------|---------| | Point absorber | Floating buoy rises and falls with waves, driving a generator | Ocean Power Technologies PowerBuoy | | Oscillating water column | Waves push air in/out of a chamber through an air turbine | Mutriku (Spain, 300 kW) | | Overtopping device | Waves wash over a raised reservoir; water returns to sea through turbines | Wave Dragon (Denmark, tested) | | Attenuator | Long floating structure flexes with waves; hinged joints drive generators | Pelamis (Scotland, tested) | | Oscillating wave surge converter | Flap mounted on the seabed oscillates with wave pressure | Aquamarine Oyster (Scotland, tested) | | Submerged pressure differential | Pressure changes from passing waves drive a generator on the seabed | CalWave xWave (U.S., testing) |
U.S. Wave Resources
| Region | Resource (TWh/year) | Wave Power (kW/m) | |--------|:-:|:-:| | West Coast (WA, OR, CA) | ~440 | 20-40 | | Alaska | ~620 | 25-50 | | Hawaii | ~80 | 15-25 | | East Coast | ~200 | 10-20 | | Gulf of Mexico | ~60 | 5-10 | | Total U.S. | ~1,400 | |
Oregon and Washington have the best combination of strong wave resource and proximity to population centers.
The PacWave Test Site
The most important U.S. wave energy infrastructure:
- Location: 7 miles off Newport, Oregon
- Purpose: Grid-connected, open-ocean wave energy test facility
- Operated by: Oregon State University, funded by DOE
- Capacity: Up to 20 MW of test berths
- Status: Construction completed; testing of wave energy devices beginning
- Significance: Provides standardized testing conditions, grid connection, and environmental monitoring — critical for proving devices work in real ocean conditions
Economics
Current Costs
Marine energy is expensive — comparable to where solar was in the early 2000s:
| Technology | Current LCOE ($/MWh) | Target LCOE by 2030s | |-----------|:-:|:-:| | Tidal stream | $200-$500+ | $100-$150 | | Wave energy | $300-$1,000+ | $100-$200 | | Tidal barrage | $150-$350 | N/A (mature but costly) | | Offshore wind (for comparison) | $60-$100 | $50-$80 |
Why Costs Are High
- Early stage: Most devices are prototypes or first-of-a-kind; no manufacturing scale
- Harsh environment: Saltwater, storms, biofouling require expensive materials and maintenance
- Installation: Deploying heavy equipment in open ocean is difficult and weather-dependent
- Maintenance: Accessing underwater devices is costly; reliability still being proven
- No supply chain: Unlike wind and solar, there's no established manufacturing ecosystem
Cost Reduction Pathway
Following the wind/solar learning curve:
- Standardized designs — industry converging on proven concepts
- Larger devices — more energy capture per unit of infrastructure
- Array deployment — economies of scale from building many devices at one site
- Improved reliability — fewer maintenance trips to sea
- Manufacturing scale — dedicated factories instead of one-off fabrication
Environmental Considerations
Potential Benefits
- Zero emissions during operation
- Small surface footprint (devices mostly submerged)
- Complements wind and solar (waves peak at different times)
- Could provide power to coastal and island communities
Potential Concerns
- Marine life interaction: Risk of collision, entanglement, habitat disruption
- Underwater noise: Turbines and generators may affect marine mammals
- Electromagnetic fields: Submarine power cables may affect species sensitive to electromagnetic fields
- Visual impact: Surface devices visible from shore (less of an issue for submerged devices)
- Seabed disruption: Anchoring and cable installation disturb benthic habitats
Key finding from early deployments: Environmental impacts have generally been less severe than initially feared. Studies at the European Marine Energy Centre (EMEC) in Scotland show marine animals largely avoid device areas without significant behavioral changes.
Comparison: Marine Energy vs. Other Renewables
| Factor | Wave | Tidal | Offshore Wind | Solar | |--------|:-:|:-:|:-:|:-:| | Predictability | Moderate (hours ahead) | Excellent (years ahead) | Good (hours/days) | Good (hours/days) | | Capacity factor | 25-35% (estimated) | 25-40% | 40-55% | 15-30% | | Current LCOE | Very high | High | Moderate | Low | | Technology maturity | Early | Early-moderate | Commercial | Commercial | | U.S. resource | Large (coasts) | Niche (specific sites) | Large (Atlantic, Pacific, Gulf) | Very large (nationwide) | | Visual impact | Low | Very low | Moderate | Low-moderate |
Federal Support
- DOE Water Power Technologies Office: ~$100M+/year for marine energy R&D
- Powering the Blue Economy: DOE initiative to develop marine energy for coastal applications
- PacWave: Federal-funded open-ocean test facility
- SBIR/STTR: Small business grants for marine energy innovation
- IRA eligibility: Marine energy qualifies for 45Y PTC and 48E ITC
- National Marine Renewable Energy Centers: Testing infrastructure at OSU, UNH, and UW
Realistic Timeline
Marine energy is not going to be a significant U.S. electricity source in the near term. A realistic timeline:
| Phase | Timeframe | Milestone | |-------|:-:|---------| | Technology validation | 2024-2028 | Proving devices survive and produce in open ocean | | Pre-commercial arrays | 2028-2035 | Small arrays (1-10 MW) demonstrating economic potential | | Early commercial | 2035-2045 | First utility-scale projects (10-100 MW) | | Mature deployment | 2045+ | Competitive installations at scale |
Niche Applications (Sooner)
Marine energy may find early commercial viability in niche applications before reaching grid-scale:
- Remote island and coastal communities with high electricity costs and no grid connection
- Ocean observing: Powering sensors, buoys, and underwater vehicles
- Aquaculture: Powering offshore fish farms
- Desalination: Wave-powered desalination for water-stressed coastal areas
- Military: Powering remote naval installations and underwater systems
The Bottom Line
Ocean energy has enormous theoretical potential — the U.S. wave resource alone could supply a third of national electricity demand. But the technology is 15-25 years behind offshore wind, which itself is still ramping up. The harsh marine environment, high costs, and lack of manufacturing scale mean ocean energy will likely remain a niche contributor for the next decade.
The case for continued investment is simple: the ocean is the largest untapped renewable resource on Earth, and early investment now (like the DOE's PacWave facility and R&D programs) seeds the technology for future deployment — just as federal wind research in the 1970s-80s seeded the 150 GW U.S. wind industry of today.