The MeyGen project being deployed (credit: Marine Energy Wales)
The global state of Marine Energy in 2025 is interesting. Although marine energy - that is wave and tidal power, tidal lagoons and barrages - amounts to only around 500MW of existing capacity worldwide, it has great potential.
The seas are everywhere, that's a lot of energy. There are many challenges: marine energy is a lot more expensive than wind or solar, and technical difficulties such as maintenance and harsh conditions are not trivial to surmount.
Factors Slowing Development
High costs and economics
Marine energy technologies remain expensive per MW compared to wind and solar. The environment, materials, marine logistics, survivability in harsh environments all add to the cost.
Regulatory and permitting barriers
Marine energy involves seabed rights, marine spatial planning, environmental permitting, grid access in remote or offshore locations. This slows development.
Technological immaturity
Devices must survive storms, biological growths, corrosion, and other negative effects. The technology is not proven at scale, yet.
Some devices have show reliability, such as MeyGen, but not at commercial scale.
Grid integration
Many marine sites are remote or offshore and require expensive cabling and substations. Interconnection and transmission costs can prove to be a barrier.
Financing and investment risk
Financing can be difficult because many projects are still at pilot or early commercial scale, so are risky from a financial perspective.
Illustration of some designs for wave and tidal generators
The EU has set targets of around 1 GW of installed ocean energy capacity by 2030, and much larger (circa 40 GW) by 2050. Although the UK has had quite a few projects in testing, apart from the 1 MW WEDUSEA floating wave energy array and the MeyGen tidal array in Scottish seas., development has been slow.
The U.S. Department of Energy (DOE) is investing significantly in marine energy R&D. More than $41 million has been allocated to marine energy research and testing in university-led national marine energy centers, together with another $18 million toward smaller R&D projects.
Around the world, Asian countries like Indonesia and the Philippines are seeking to play to their strengths of long coastlines, islands and powerful currents, to reduce their reliance on diesel generation. Some projects are:
The Philippines' Capul Island is a 1 MW tidal energy project (using tidal stream / current turbines) which is being built in Northern Samar (San Bernardino Strait). It will supplement an off-grid diesel plant there. Scheduled for deployment by late 2025.
Indonesia
HydroWing has binding agreement for a 10 MW tidal current power plant in East Nusa Tenggara.
Renewed Interest in Tidal Lagoons and Barrages
High energy costs have renewed interest in tidal lagoons enclosing an area of water, and tidal barrages across rivers. Though the capital costs are high, the technology is relatively simple and proven. France has had a functional tidal lagoon running for over five decades. Sihwa Lake in South Korea is still the largest existing tidal barrage by capacity; it has been operational for years.
The Future of Marine Energy
Overall, there is a significant potential for generation of energy. A realistic estimate for global energy production in this sector is 2,000-4,000 TWh for waves, plus perhaps several thousand more for tidal and currents, which could be around 10-15% for nations with good marine energy resources.
Compared to other renewables, marine energy is much less developed: cost per kWh remains higher, maintenance and deployment harder, with few smaller scale projects fully operational. The value of this emerging technology is in predictability, energy density, and potential for locations where other energy generation resources, whether fossil fuel or renewables, is not optimal.