Ships could be transformed into green energy generators by installing devices that capture wave energy to help meet on-board power needs, according to a team of Chinese researchers.
In a paper published in the journal Renewable Energy, the researchers proposed a new device that could help decarbonise one of the world’s most energy-hungry sectors that is a significant source of emissions.
“Ocean renewable energy sources are gaining increasing attention as a means of addressing the global energy crisis and mitigating climate change,” said the researchers.
“Wave energy has the potential to provide a substantial amount of clean and sustainable power,” which could be stored and used to meet on-board electricity requirements.
The researchers proposed a “novel concept” of using devices called “heaving oscillators” inside a ship's structure to capture this energy.
The system consists of a frame that is securely attached to the vessel at both its top and bottom. An oscillator is attached to this structure and moves up and down slide rods when the ship moves from side to side.
A spring and hydraulic cylinder are located at the bottom of the oscillator, and the mechanical energy is transformed into electrical energy by using it to drive a hydraulic generator.
By placing the system inside the ship, the team said it would have “no significantly adverse effects on the ship seakeeping performance,” and would help preserve deck space.
It also “capitalises on the kinetic energy produced by the ship heaving, rolling, and pitch motion to generate electrical energy under multi-directional waves.”
The team found that the device could capture 91% of the energy on offer under ideal wave conditions.
“This underscores that the current concept holds significant potential for efficiently harnessing wave energy under specific wave conditions.”
One of the lead researchers, Yao Liu, a postdoctoral researcher at the Shanghai Ship and Shipping Research Institute, a subsidiary of maritime giant COSCO Shipping, told Recharge that the concept could “easily be extended to other marine engineering structures, such as offshore platforms and buoys."
The next step for the development of the concept, which is still at an early stage, will be to carry out in-laboratory experiments using a scaled-down model in wave tanks.
While innovations such as the heaving oscillator address auxiliary power, wider efforts are underway to tackle propulsion, which is the main source of vessels' energy use, notably through moves to introduce e-methanol produced using green hydrogen.
