Harvesting Broad Frequency Band Blue Energy by a Triboelectric–Electromagnetic Hybrid Nanogenerator

TLDR

Ocean wave energy is abundant yet underutilized because its low frequency and irregular amplitude make it difficult for conventional generators to harvest. This study introduces a hybrid nanogenerator combining a spiral‑interdigitated triboelectric unit (S‑TENG) and a wrap‑around electromagnetic generator (W‑EMG) to harvest ocean energy. The design isolates the S‑TENG from the environment, drives it via non‑contact magnetic attraction, and couples it with a W‑EMG that can be easily hybridized, enabling a floating system that simultaneously captures wind, solar, and wave energy. The hybrid nanogenerator generates electricity in both rotation and fluctuation modes across a broad frequency range, proving effective in driving LEDs under simulated wave conditions and demonstrating superior performance at low (<2 Hz) and high (>10 Hz) frequencies.

Abstract

Ocean wave associated energy is huge, but it has little use toward world energy. Although such blue energy is capable of meeting all of our energy needs, there is no effective way to harvest it due to its low frequency and irregular amplitude, which may restrict the application of traditional power generators. In this work, we report a hybrid nanogenerator that consists of a spiral-interdigitated-electrode triboelectric nanogenerator (S-TENG) and a wrap-around electromagnetic generator (W-EMG) for harvesting ocean energy. In this design, the S-TENG can be fully isolated from the external environment through packaging and indirectly driven by the noncontact attractive forces between pairs of magnets, and W-EMG can be easily hybridized. Notably, the hybrid nanogenerator could generate electricity under either rotation mode or fluctuation mode to collect energy in ocean tide, current, and wave energy due to the unique structural design. In addition, the characteristics and advantages of outputs indicate that the S-TENG is irreplaceable for harvesting low rotation speeds (<100 rpm) or motion frequencies (<2 Hz) energy, which fits the frequency range for most of the water wave based blue energy, while W-EMG is able to produce larger output at high frequencies (>10 Hz). The complementary output can be maximized and hybridized for harvesting energy in a broad frequency range. Finally, a single hybrid nanogenerator unit was demonstrated to harvest blue energy as a practical power source to drive several LEDs under different simulated water wave conditions. We also proposed a blue energy harvesting system floating on the ocean surface that could simultaneously harvest wind, solar, and wave energy. The proposed hybrid nanogenerator renders an effective and sustainable progress in practical applications of the hybrid nanogenerator toward harvesting water wave energy offered by nature.