An ocean-powered buoy brings technology closer to the dream of obtaining energy from the sea
Though the project's scale is small so far, the researchers say it is an important proof of concept for a technique that could supplement existing attempts to harness the power of waves, as well as other kinds of naturally occurring motion.
Wave patterns are unpredictable, seawater corrodes metal generating machinery, and waves' energy is simultaneously dispersed across three dimensions.
In part because of such challenges, the electrical output from several nascent, large-scale wave power projects has lagged behind predictions.
The team turned to so-called triboelectric nanogenerators, or TENGs, which convert motion into an electrical current using static electricity-the same principle as rubbing a balloon on a fuzzy sweater to generate charge.
"The devices are low-cost. They reach high power densities [with] high efficiencies," Rodrigues says, adding that TENGs continue to perform well even when waves are small and infrequent.
TENGs can generate power from any form of motion, but Rodrigues and her collaborators have focused on testing various TENG prototypes to optimize them for the specific conditions of wave motion.
They placed the model in a wave pool and simulated the five most frequent wave patterns that occur in the seaport in nearby Figueira da Foz, Portugal.
The new study marked the first time they have been tested under such realistic wave conditions, Rodrigues says.
This method produces potentially problematic loud noises, and it only takes advantage of the vertical motion of a wave.
Based on the success of their wave pool trials, the researchers plan to modify their TENG prototype and install it in a full-scale buoy in Figueira da Foz.