Table of Contents
Introduction
Advanced ocean energy concepts explore how to harvest energy from the sea in ways that go beyond the more established tidal and wave technologies. While basic tidal and wave principles are introduced elsewhere, this chapter focuses on novel ideas, experimental systems, and combinations of technologies that are still emerging. These concepts are important because they can expand the range of usable marine environments and offer new options for integrating ocean energy into broader energy systems.
Broad Categories Of Advanced Ocean Concepts
Advanced ocean energy concepts can be grouped into several broad categories. Some focus on capturing energy from deeper or more complex wave and current conditions. Others combine multiple sources of energy in a single location or device, for example wave plus wind or wave plus solar. There are also ideas that use temperature and salinity differences more efficiently or at smaller scales than traditional designs.
Unlike mature hydropower or onshore wind, most advanced ocean technologies are in research, prototype, or early demonstration stages. This affects their costs, reliability, and the amount of real world data that exists. However, the variety of concepts illustrates how rich the ocean resource is and how many technical approaches can be imagined.
Novel Wave Energy Converter Concepts
Conventional wave energy devices often fall into familiar types such as point absorbers, oscillating water columns, or attenuators. Advanced concepts experiment with geometry, control strategies, and installation locations to increase energy capture and survivability.
Some devices use articulated structures that can change shape in response to incoming waves. They may use active control systems that sense wave conditions and adjust damping, stiffness, or orientation to maximize power. Others are designed to be installed at greater depths below the surface where wave motion is smaller but more regular. Submerged devices can be less exposed to storms and may use hydraulic or pneumatic transmission to send energy to a surface or seabed power unit.
There is also growing interest in flexible or fabric based wave devices that behave more like membranes or inflatable structures. These can be lighter and potentially cheaper to deploy, although they introduce new material and durability challenges. Advanced numerical models and laboratory experiments guide the optimization of shapes and control algorithms before field testing.
Advanced Tidal And Ocean Current Concepts
Basic tidal energy systems typically use turbines placed in locations where water flows strongly due to tides. Advanced concepts explore variations in turbine design, placement, and operating strategies to expand usable sites and improve efficiency.
One line of development focuses on vertical axis turbines that can accept flow from multiple directions without active yaw control. Another explores cross flow designs and enclosed duct or diffuser systems that accelerate water through the turbine. Some advanced concepts use turbine arrays that are carefully arranged to manage wake interactions, so the overall farm captures more energy than a simple alignment would allow.
Ocean current concepts extend beyond purely tidal flows. In regions with persistent large scale currents, devices are envisioned that can remain submerged for long periods and harvest relatively steady power. Tethered systems, which look conceptually similar to underwater kites, can move through the water along controlled paths. By flying across the flow, they can increase the relative speed over the turbine rotor and hence power output.
Hybrid Marine Energy Platforms
Hybrid marine platforms combine multiple renewable energy technologies in the same offshore structure or area. For example, a platform might support wind turbines above the surface, wave energy converters around its perimeter, and possibly solar panels on top. The idea is to use the same infrastructure, such as moorings, subsea cables, and maintenance vessels, for several technologies at once.
In some concepts, wave devices mounted on floating wind foundations use the motion of the platform or the surrounding waves to produce electricity. In others, buoys with integrated solar and wave components can provide reliable power in remote marine locations. By combining sources that have different variability patterns, hybrid systems seek to deliver more stable power and improve the overall economics of offshore renewable projects.
Hybrid platforms can also be integrated with non energy marine uses, such as aquaculture or desalination. Co locating fish farms and energy systems is being studied as a way to make better use of ocean space and reduce operating costs through shared logistics.
Salinity Gradient And Osmotic Power
Salinity gradient energy, sometimes called blue energy, aims to capture the energy released when freshwater and saltwater mix. The basic principle is that when water with different salt concentrations comes into contact, there is a chemical potential difference that can be converted into electricity.
Advanced concepts in this area rely on membrane technology and electrochemical processes. In pressure retarded osmosis, for example, freshwater passes through a semi permeable membrane into saltwater, increasing its pressure. This pressure can be used to drive a turbine. In reverse electrodialysis, ion selective membranes allow charged ions to move between freshwater and saltwater compartments, creating an electrical potential across electrodes.
These systems are typically located at estuaries where rivers meet the sea. The main challenges relate to membrane performance, fouling, and cost. Research aims to improve membrane materials, flow channel design, and operational strategies, in order to reach commercially viable power densities and lifetimes.
Distributed And Niche Ocean Energy Devices
Not all advanced ocean energy concepts target large scale grid supply. Some focus on smaller, distributed applications. These devices are often designed to power specific uses in the marine environment, such as navigation buoys, environmental sensors, offshore communication nodes, or small desalination units.
Wave powered desalination buoys, for instance, use wave motion to drive pumps that pressurize seawater for reverse osmosis, producing fresh water without electricity as an intermediate step. Similarly, small wave or current energy converters can charge batteries on remote platforms, reducing the need for diesel generators.
Advanced designs in this niche segment emphasize reliability, low maintenance, and ease of deployment, since access to offshore sites can be difficult and costly. Standardization and modularity are important to support flexible use cases and scale out when needed.
Control, Materials, And Digital Innovations
Several technological trends support advanced ocean energy concepts. Improved materials and coatings aim to resist corrosion, biofouling, and mechanical fatigue in harsh marine conditions, while keeping costs and environmental impacts under control. Composites, advanced steels, and new polymers are all under investigation.
Digital innovations such as real time monitoring, data driven control, and predictive maintenance play a growing role. Sensors embedded in devices collect information on loads, motions, and environmental conditions. This data can feed control algorithms that adjust device settings for optimal performance and survival. It can also support condition based maintenance, where interventions are planned before failures occur.
Numerical simulations and digital twins allow developers to test many design variations virtually before choosing which prototypes to build. By integrating environmental data, hydrodynamic models, and structural analysis, these tools help reduce uncertainty and accelerate learning.
Integration With Energy Systems And Uses
Advanced ocean energy concepts do not exist in isolation. Their ultimate value depends on how well they connect to broader energy systems and uses. Some concepts are designed to feed electricity directly into coastal grids, possibly through shared offshore substations with wind farms. Others serve as local power sources for islands, offshore facilities, or coastal industries.
There is also growing interest in coupling ocean energy with energy storage and conversion technologies. For example, surplus generation from wave or tidal devices could power electrolyzers to produce hydrogen offshore. This hydrogen could then be transported to shore by pipeline or ship. In such a scheme, ocean energy becomes part of a larger power to X chain that can serve transport, industry, or heating sectors.
Because marine resources can be located far from demand centers, careful planning of transmission, storage, and local uses is essential. This planning must also consider marine spatial planning, shipping routes, ecological sensitivities, and other users of the sea.
Technical And Environmental Challenges
Advanced ocean concepts face a combination of technical, economic, and environmental challenges. Devices must survive storms, corrosion, and biofouling for many years, while maintaining efficient operation. Installation and maintenance costs are high, so reliability and ease of access are crucial. In many cases, there is still limited long term operational data, which makes it harder to attract investment.
Potential environmental impacts include interactions with marine life, changes in local hydrodynamics, and the risk of pollution from accidental releases of oils or other substances. While the overall footprint of ocean energy is often smaller than large hydropower dams, each new concept must be assessed in context. Environmental monitoring and adaptive management help to identify and mitigate impacts.
Regulatory frameworks are also still evolving. Permitting processes for novel devices can be complex because regulators may lack established guidelines. Developers and authorities must work together to define appropriate standards and monitoring requirements.
Outlook And Innovation Pathways
The future of advanced ocean energy concepts depends on continued research, demonstration projects, and learning by doing. Early stage prototypes help identify design weaknesses and validate performance models. Over time, scaling up device size and project capacity can reduce costs, as has been observed for other renewables.
Some concepts may eventually become mainstream, while others will remain specialized or be replaced by better ideas. Hybrid systems and multi use platforms are likely to gain importance as ocean space becomes more crowded and as offshore activities diversify. Integration with offshore wind and aquaculture may provide important synergies.
Ultimately, advanced ocean energy concepts expand the toolbox of renewable options, especially for coastal and island regions. Their development illustrates how innovation, experimentation, and interdisciplinary collaboration can open new possibilities for sustainable energy from the sea.