Bubble energy harvesting suitable for weak gas sources using bubble stream release scheme

The subsea observation network can provide a window for human underwater exploration, but existing power solutions fail to provide sustainable and maintenance-free power for its widespread nodes. The ocean contains a vast amount of bubble potential energy, which has yet to be extracted as an energy source. Existing bubble energy harvesting systems rely heavily on the considerable number of bubbles to generate high enough velocity, incapable of fully utilizing widely distributed weak gas sources. In this work, we propose a bubble stream release scheme specifically designed for weak gas sources, based on the threshold matching principle of the energy harvesting system. Compared to systems that cannot harvest any energy from weak gases, we use a large bubble to start the system and the following small bubbles can generate electricity that otherwise would be wasted. In a system with a height of 1.6 m, the energy density of the bubble stream release scheme reaches 119.31 mJ/L, which is 7.6 times higher than that of the conventional scheme. The advantages of the bubble stream release scheme become more significant as the system height increases. This research allows abundant weak gas sources to become a promising energy source for subsea observation network nodes, accelerating the development of the smart ocean.