Efficient bubble energy harvesting by promoting pressure potential energy release using helix flow channel

Abstract

The bubble energy harvesting system can provide in-situ energy supply for the subsea observation equipment through two stages of energy conversion. However, the conversion efficiency of bubble potential energy to fluid energy in the first stage is much lower than that of fluid energy to electrical energy in the second stage, limiting the output capability of the bubble energy harvesting system. Here, a complete energy transfer and conversion model for the subsea bubble energy harvesting is established for the first time. Regardless of the type of transducer used in the system, increasing the released pressure potential energy can substantially improve the efficiency of bubble energy harvesting. Based on this mechanism, we proposed a method to improve the released pressure potential energy and verified the results using a bubble energy harvesting system with a 3D streamline. The flow velocity and fluid volume of the system can be controlled by adjusting the helix angle and cylindrical diameter. Compared with the original system, the fluid pressure potential energy released of a 3D-system with a helix angle of 50 degrees can increase by at least 26%. The output energy density of the 3D-system with a height of 1.6 m can reach 6.6 J/m3, which is 59 times higher than that of the existing technology. This technology can efficiently harvest energy from subsea gas sources, and has the potential to become a long-term in-situ power supply solution for subsea observation networks.