Tiny Wave Generators Target Ocean Sensors, but the 117% Efficiency Claim Needs Clarification

A striking number at the centre of ocean energy research

Tiny generators designed to turn ocean waves into electricity are being credited with a reported 117% power conversion efficiency in real marine conditions, alongside designs delivering volumetric power densities above 600 watts per cubic metre. Researchers at the Beijing Institute of Nanoenergy and Nanosystems and Guangxi University are developing structures intended to capture the slow, irregular movement of waves and supply electricity to equipment at sea.

The potential applications range from environmental sensors and navigation lights to networks of connected marine instruments and hydrogen production from seawater. As of August 31, 2025, the work describes a developing approach to ocean energy, with laboratory demonstrations and sea trials supporting some applications while manufacturing, durability and testing standards remain challenges.

The 117% figure requires care. Conventional energy conversion efficiency measures useful electricity against the energy supplied, and a generator cannot deliver more energy than it receives. The reported figure is associated with combining different harvesting mechanisms, but its calculation and comparison baseline are not specified. A defined measurement is needed to explain what the percentage represents.

The practical development is easier to understand: engineers are finding ways to collect electricity from wave movements that are slow, change direction and arrive unevenly. For instruments operating far from shore, even modest amounts of usable electricity could reduce dependence on replacement batteries and maintenance visits.

How contact and separation generate electricity

Triboelectric nanogenerators, usually shortened to TENGs, convert mechanical movement into electricity through the triboelectric effect. Certain materials acquire electrical charge when they touch and then separate. TENGs combine this effect with electrostatic induction, using changes in the arrangement of electrical charges to generate an electrical output.

Inside a wave energy device, the rise, fall or rolling movement of the surrounding water repeatedly brings components into contact and separates them. The design turns those repeated movements into opportunities to collect energy, including when the motion is irregular or comes from different directions.

Traditional electromagnetic generators face difficulties when movement is slow. The comparison presented for these marine applications describes them as heavier and more costly, with lower efficiency at low frequencies. TENGs offer lightweight construction and are presented as a potentially economical alternative for harvesting this kind of motion.

Their modular construction also suits distributed instruments. Instead of depending on a single large generating station, a marine monitoring network could use smaller harvesting units near the equipment that needs electricity. The aim is to support devices spread across the ocean, including the marine Internet of Things, meaning connected instruments that gather and exchange information at sea.

Six structures tackle different engineering problems

Researchers at the Beijing Institute of Nanoenergy and Nanosystems and Guangxi University have developed six TENG structures described as addressing different problems in marine energy collection. Designs discussed in Nano-Micro Letters include multilayer stacks, origami folds, frames using magnetic levitation, spheres and dodecahedral structures.

Each arrangement changes how much generating material fits inside a device, how moving parts interact or how the generator responds to waves. Origami folds increase the surface area available for charge transfer. Multilayer construction places generating surfaces in a compact volume, making use of limited internal space.

Magnetic levitation cores reduce friction and wear, with the aim of extending operating life. Spherical structures and tensegrity structures, which combine tension and compression within a framework, are intended to collect motion from all directions. This helps address directions from which a more restricted mechanism would collect little energy.

The reported volumetric power densities exceed 600 W/m³, surpassing earlier prototypes. This measure describes electrical power relative to device volume. It addresses how compact a generator can be for a given output, a different engineering concern from the percentage of incoming energy converted into electricity.

Why researchers combine several kinds of generators

Hybrid systems combine TENGs with electromagnetic generators, piezoelectric generators or solar cells. Electromagnetic generators are abbreviated as EMGs, while piezoelectric generators, or PENGs, produce electricity when their materials are mechanically deformed. The purpose of combining technologies is to collect energy across a broader range of movements and environmental conditions.

Frequency complementary coupling links mechanisms that respond well to different movement frequencies. A wave does not deliver the steady rotation that many conventional generators prefer. A hybrid device can use different components to capture useful energy as the movement changes.

The reported 117% figure is attributed to such combinations. The explanation given is that several mechanisms collect more energy from the same wave input than a more limited arrangement. The missing calculation leaves the relationship between that claimed improvement and the stated efficiency unresolved.

One hybrid design uses a chaotic pendulum and separates the movement of the floating body from that of the internal generator. The mechanism transforms irregular wave movement into more stable rotation. Open sea trials are described as demonstrating operation of marine sensors and navigation lights, connecting the engineering approach to specific tasks rather than electricity generation alone.

A buoy shows what small amounts of power can support

Ocean buoys equipped with TENGs have demonstrated support for satellite communications, commercial sensors and environmental monitoring over extended periods. The applications include remote and harsh conditions such as those in the Arctic Ocean, where access for maintenance can be difficult.

In one sea trial, a buoy containing a cylindrical TENG operating on both sides generated enough electricity to transmit more than 500 bytes of data daily despite challenging waves and temperatures. The demonstration links energy collection to a concrete service: sending measurements from an instrument at sea.

Marine Internet of Things networks depend on many such devices collecting and communicating information. Potential uses include monitoring water quality, tracking environmental conditions and supporting maritime safety. Navigation beacons, autonomous underwater vehicles and sensor platforms are also identified as possible beneficiaries.

Electricity collected where an instrument operates could reduce the need to replace its batteries. The longer term ambition is to remove that requirement for suitable installations, cutting maintenance costs and the environmental burden associated with servicing remote equipment. Achieving that outcome depends on reliable power collection, storage and operation throughout changing conditions.

Following waves and making better use of small movements

Wave direction presents a separate problem from wave strength. A device may receive enough movement to generate useful electricity, yet collect less if its mechanism is poorly aligned. Adaptive TENG structures are being developed to respond to that changing direction.

Butterfly stacked TENGs use platforms inspired by sunflowers that rotate to face incoming waves without an external power supply. The arrangement aims to keep the generating structure aligned with the movement it is collecting, increasing energy capture as conditions change.

Lever mechanisms address another feature of wave motion. They turn movement with a small amplitude and high torque into movement with a larger amplitude and lower torque. In simpler terms, they trade a shorter, stronger movement for a longer movement that can better suit the internal generating mechanism, increasing charge output.

Gyroscope structures and rolling designs provide other ways to collect motion from several directions. Inner and outer generating units can operate independently, allowing different parts of a device to respond to the surrounding movement. These systems have been tested in laboratories and at sea, including demonstrations powering commercial electronics.

Durability results include devices showing less than 8% output loss after 30 days submerged. That offers a specific measure of performance over an extended test, while the broader commercial challenge remains maintaining reliable output through much longer exposure to marine conditions.

Connecting individual devices into larger arrays

TENG units can be linked into chains or arranged across a plane to create larger harvesting networks. These arrangements are described as one dimensional and two dimensional arrays. Their purpose is to collect energy across a wider area while retaining separate modules that can be assembled, maintained or replaced individually.

Some modular designs use planetary gear mechanisms to increase the frequency of movement reaching the generator. This process, called frequency upconversion, turns slow wave motion into faster generator rotation. It is another way of matching the movement supplied by the sea to the movement a generating component can use effectively.

Electrical connections matter alongside the moving parts. Rectifier bridges and charge excitation arrangements are used to manage output and reduce losses across arrays. A rectifier directs electrical output into a consistent direction, helping prepare it for subsequent power management.

Hydrodynamic modelling examines how water movement interacts with devices and networks. Combined with testing in real conditions, it is intended to guide arrangements that withstand marine forces while maintaining reliable generation. The engineering task therefore extends from the contact surfaces inside a single generator to the behaviour of an entire connected array.

Testing standards and durability shape commercial prospects

Commercial deployment faces four main challenges: consistent performance measurement, resistance to marine corrosion and wear, effective energy management and grid integration, and economical manufacturing and installation at scale. Progress in one area still leaves the others to be addressed.

A review of testing practices highlights inconsistent conditions and evaluation methods behind widely varying TENG performance claims. Fabrication details, mechanical arrangements and environmental conditions can all affect electrical output. Researchers are calling for international standards to make results reproducible and comparisons more useful.

Consistent measurements would help answer practical questions for a buoy operator or network developer: how much usable power a device supplies, under which wave conditions, and for how long. The unresolved definition of the 117% figure makes precise reporting of measurement methods especially relevant.

Environmental protection is also part of the development work. Proposals include using recycled ocean plastics in TENG construction, creating smart materials intended to reduce maintenance, and planning for reuse or recovery of materials when equipment reaches the end of its operating life. These approaches aim to address the devices themselves as well as the electricity they produce.

From ocean measurements to wider energy ambitions

Distributed marine sensors are a direct application of the technology described so far. Instruments that collect their own electricity could support continuing observations of ocean health, climate conditions and maritime activity, extending monitoring into places where regular servicing is costly or difficult.

Larger networks are proposed as a basis for ocean energy grids. Combining TENGs with wind and solar generation could provide multiple sources of electricity for offshore platforms, aquaculture and, eventually, coastal communities. These are broader ambitions than the specific sensor and navigation light demonstrations described in sea trials.

Hydrogen production through seawater electrolysis is another proposed application. Electrolysis uses electricity to split water to produce hydrogen. Connecting that process to wave energy would provide a route to fuel production at sea, although the account gives no production rate or deployment timetable.

The immediate engineering priorities remain concrete: collect irregular movement efficiently, keep equipment working in saltwater, turn fluctuating output into usable power and measure results consistently. Small generators already have described uses in marine communications and sensing. Expanding them into dependable networks requires those individual functions to work together over sustained periods.

Key Points

• Researchers at the Beijing Institute of Nanoenergy and Nanosystems and Guangxi University are developing six TENG structures for collecting ocean wave energy.
• A reported 117% efficiency figure is associated with hybrid harvesting, but its calculation and comparison baseline are unspecified.
• Reported volumetric power densities exceed 600 W/m³, while designs use folds, magnetic levitation, spheres and other structures to improve collection.
• A cylindrical TENG buoy generated enough power to transmit more than 500 bytes of data daily during a sea trial.
• Some devices showed less than 8% output loss after 30 days submerged.
• Marine sensors and navigation lights feature in demonstrations; larger energy networks and seawater hydrogen production remain proposed applications.
• Testing standards, durability, power management, manufacturing costs and environmental planning are central to commercial development.