Wave and tidal power represent enormous untapped renewable potential. Predictable, high energy density, and complementary to solar and wind. Yet global deployment is still under 1 GW. This guide covers why marine renewables are lagging and where they might scale.
Wave vs tidal
| Attribute | Wave | Tidal |
|---|---|---|
| Energy source | Wind driven surface waves | Moon gravity via tides |
| Predictability | Hours ahead | Years ahead |
| Deployment | Offshore devices | Barrages or in stream turbines |
| Commercial scale | Very limited | Very limited |
| Best sites | Atlantic and Pacific coasts | Areas with high tidal range |
Current global scale
Tidal barrage
Dam like structure across estuary. Sluice gates let water in during flood tide, then close. During ebb tide, water released through turbines. Predictable but disruptive to estuarine ecosystems.
Major tidal barrages
- Sihwa Lake South Korea (254 MW, world largest).
- La Rance France (240 MW, operating since 1966).
- Annapolis Nova Scotia (retired).
- Kislaya Guba Russia (small pilot).
- Jiangxia China (small pilot).
In stream tidal
Underwater turbines similar to wind turbines but powered by tidal currents. No barrage. Lower environmental impact but smaller capacity per unit. Various technologies developed but limited commercial scale.
Major in stream projects
| Project | Location | Notes |
|---|---|---|
| MeyGen | Scotland | ~6 MW operating; largest tidal array |
| Uisce Tapa | Ireland | Planned tidal array |
| Verdant Power East River | New York | Small pilot |
| Sabella | France | Various pilots |
| ORPC Cobscook | Maine | Small pilot |
Wave energy devices
| Type | Concept |
|---|---|
| Point absorber | Floating buoy captures vertical motion |
| Attenuator | Segmented device parallel to wave direction |
| Oscillating water column | Air chamber pressurised by waves drives turbine |
| Overtopping | Waves overtop structure into reservoir |
| Oscillating wave surge | Flap perpendicular to wave direction |
| Submerged pressure differential | Wave pressure changes on seabed device |
Wave developers
- CorPower Ocean (Sweden, point absorber).
- Ocean Power Technologies (US, buoy design).
- Wello Oy (Finland, rotating design).
- AW Energy (Finland, oscillating wave surge).
- Carnegie Clean Energy (Australia, submerged buoy).
- SEENERGY (China).
Why marine renewables lag
Where marine renewables shine
- Highly predictable (tidal).
- High energy density (waves).
- Complementary to solar and wind.
- Coastal load center proximity.
- Low visual impact for submerged devices.
- Coastal community jobs.
Cost challenges
| Technology | LCOE current |
|---|---|
| Tidal barrage (existing) | Amortized low |
| New tidal barrage | USD 200 to 400 per MWh |
| In stream tidal | USD 200 to 500 per MWh |
| Wave | USD 300 to 700 per MWh |
| 2030 targets | USD 100 to 200 per MWh |
Regional focus areas
| Region | Notes |
|---|---|
| Scotland | Pentland Firth strong tidal resource |
| Ireland | West coast wave resource |
| Portugal | Wave energy pioneers |
| Australia | Wave energy testing |
| Chile | Excellent wave resource |
| US Pacific Northwest | Wave energy test facility |
| Canada Bay of Fundy | Highest tidal range globally |
| France | Historical tidal barrage plus new pilots |
Policy support
UK Contracts for Difference has ring fenced allocation for tidal. Scottish government continued support. EU Ocean Energy Strategy. US DOE Water Power Technologies Office. Multi hundred million dollar cumulative but small versus scale needed.
Future outlook
Ocean thermal energy conversion (OTEC)
Related but different technology using temperature difference between surface and deep water. Effective only in tropical regions. Very limited deployment. Still research stage.
Salinity gradient
Blue energy from mixing fresh water with salt water at river mouths. Research stage. Not commercial.
Grid integration challenges
Coastal generation often distant from grid points. Undersea cable transmission expensive. Grid capacity in coastal regions may need expansion.
Where marine renewables are going
- Continued tidal barrage operation.
- MeyGen expansion to test in stream tidal at scale.
- Wave technology reliability improvement.
- Cost reduction with survival.
- Coastal off grid deployment.
- Modest scale contribution by 2050.
Frequently asked questions
What is tidal power?
Electricity from tidal water movement.
What is wave power?
Electricity from ocean wave motion.
Are they commercial?
Very limited scale. Tidal barrages yes; in stream tidal and wave largely pilot.
Are they reliable?
Tidal barrages very reliable. Wave devices challenging.
Can they scale?
Potentially. Cost reduction and reliability improvements needed.
Where does the biggest tidal barrage exist?
Sihwa South Korea, 254 MW.
Where is the biggest tidal array?
MeyGen Scotland, growing.
Are they environmentally clean?
Barrages disrupt estuaries. In stream and wave less so.
What is OTEC?
Ocean thermal energy conversion. Uses temperature difference.
Where can I read more?
Ocean Energy Systems, EMEC (European Marine Energy Centre).
Summary
Wave and tidal power offer significant untapped renewable potential but deployment lags far behind solar and wind. Tidal barrages proven and reliable. In stream tidal and wave still developing. Marine environment reliability is major challenge. Cost trajectories improving but far from solar plus wind competitive. May reach commercial scale in 2030s for specific applications. Modest contribution to global energy mix realistic.
Next reading
- How hydroelectric power works
- Offshore wind complete guide
- Renewable energy complete guide
- Browse the UtilityRadar directory
See the assets in this article
Explore 177,000+ utility infrastructure sites
Locations, capacity, operators, and permits across 24 sectors: the same records our writers pull from.
Start browsingOperations guides from the UtilityRadar team.