One key to collecting clean energy from the ocean-at least a small part of it-may lie in static electricity. A group of researchers in Portugal have now successfully used it to run a small generator inside the navigation buoy to power the sensors and lights that the buoy uses to collect data and help sailors. Although the scale of the project so far is small, the researchers say that it is an important proof of concept that can complement existing techniques that use waves and other types of naturally occurring motion attempts.
The ocean is an attractive target for renewable energy generation.Only waves are generated 32,000 TWh Annual natural energy-for reference, used all over the world 23,000 terawatt hours Per year. There is also the power of ocean currents, tides, and heat. However, despite decades of research, the facts have proved that the movement of the ocean is difficult to control. Wave patterns are unpredictable. Sea water corrodes metal generators, and wave energy is simultaneously dispersed in three dimensions (up and down, front and back, and left and right).
Partly due to these challenges, the power output of several emerging large-scale wave power projects has been Behind forecastThe Portuguese researchers turned to something smaller and more manageable: powering navigation buoys, which usually contain lights to guide ships and sensors to monitor ocean conditions. The team turned to the so-called tribo-nano-generator, or TENG, which uses static electricity to convert motion into electric current—the principle is the same as rubbing a balloon on a furry sweater to generate an electric charge. The core of each TENG is two surfaces, the area is only a few square centimeters, it is easy to be positively or negatively charged. On the two stacked surfaces, the researchers placed 10 stainless steel balls, about 12 mm in diameter, that can move freely. When their container is tilted, the ball will roll and rub the two surfaces together. This will form a static charge, which can be converted into electrical energy to power the battery.
“We have developed these new devices that convert rhythm and mechanical energy into electrical energy,” said Cátia Rodrigues, PhD in nanotechnology. Student at the University of Porto in Portugal. Last week, she gave a speech in a speech about her team’s wave-powered buoy. American Physical Society Meeting It was held online. “These devices are low cost. They achieve high power density [with] High efficiency,” Rodriguez said, adding that even if the waves are small and infrequent, TENG can continue to perform well.
TENG can generate power from any form of motion, but Rodrigues and her collaborators have been focusing on testing various TENG prototypes to optimize them for specific wave motion conditions. In a recent test, she and her colleagues wanted to see which setting would generate the most electricity most stably: put all the balls in a round basin shaped like a shallow bowl, or like a swimmer for each The ball creates a separate “trajectory”. Lanes of the swimming pool.
The team worked in the hydraulic laboratory of the University of Porto and tested the TENG design embedded in an eighth-scale replica of the ocean buoy. They placed the model in a wave pool and simulated the five most common wave patterns that appear in the harbor near Figueira da Foz, Portugal.
TENG was invented in 2012 by a researcher from Georgia Institute of Technology. This new study marks the first time they have been tested under such real wave conditions, Rodriguez said. It was a success: the swimlane TENG design produced a maximum output of 230 microwatts-Enough to power small devices For example, medical implants. Compared with the bowl-shaped design, it also converts energy more consistently under different wave conditions. Rodrigues said that the output can be increased by combining multiple TENGs or adding nanoparticles to the surface underneath the metal ball, thereby increasing the material’s ability to collect charges.
Andrew Hamilton, chairman of the engineering department of the Monterey Bay Aquarium Research Institute in California, said that TENG may provide a solution to a key problem that hinders other ocean energy technologies, and he is not involved in this new work. He said that the ocean is a powerful, low-speed system: it contains a lot of energy, but this energy is widely distributed. Therefore, traditional rotating generators usually require more energy than a small piece of ocean can provide to generate electricity, and other attempts to develop wave-powered buoys have drawbacks. Monterey Bay’s own buoy project uses the difference in motion between the surface of the water and a platform suspended below tens to hundreds of meters to generate electricity. But to work in very deep places, this requires a very long cable, which will be damaged by breaking waves and underwater ocean currents. 2017 year Navigation buoys in India Use an oscillating water column system to power itself: waves alternately fill and empty partially submerged chambers, accelerating air in and out of the water column. The fast-moving air then turns the turbine to generate electricity. But this method can produce potentially problematic loud noises, and it only uses the vertical motion of the waves.
The small size of TENG helps avoid these two pitfalls.Rodriguez says Compactness is one of its benefits, Enabling researchers to easily combine TENG with other power generation methods such as solar panels or different types of wave energy collectors. Based on the success of the wave pool test, the researchers plan to modify their TENG prototype and install it in the full-scale buoy of Figueira da Foz. Hamilton pointed out that high seas testing may present challenges that cannot be simulated in wave pools. “Anything you design for use in the ocean throughout the year, you have to design it for storms that are statistically likely to occur once every 100 years,” he said. He explained that over time, such extreme weatherproofing measures usually make the equipment larger, less maneuverable, and less durable, because the increased surface area provides more opportunities for wear.
Rodriguez is not discouraged. She said that she is not only studying the performance of TENG in the ocean, but also studying its performance under other “bad conditions”, including when they are placed in a groundwater extraction well-and sewn on the insole. These wide-ranging applications are the reason why she hopes to see TENG “ubiquitous” in the future.