Various energy storage systems have been invented in order to resolve the problem of intermittent power generation from renewable energy due to different weathers and seasons, and now the International Institute for Applied Systems Analysis (IIASA) has proposed a pristine energy storage solution, which is the Buoyancy Energy Storage Technology (BEST) that stores a sizeable amount of electricity with a cheaper price.

When swimming, some of us would have tried to press swim rings, buoys, or water wings into the water and watched them float back up to the water surface. This is how BEST essentially works-- by actuating the power generator through the kinetic energy derived when an object is rising rapidly to the sea surface.

In the envisage of the team, it is a vertical energy storage system concatenated by a cable, where a deeply anchored platform is established at the seabed, and a cable is used to concatenate the buoyancy device and the power generator.  Among these, the buoyancy device is set up in a large square array that is packed with high-density polyethylene pipelines that are filled with compressed air or compressed hydrogen, and the power generator is located at the very bottom.

（Source：IIASA）

The array is first pulled down to the sea for fixation when in need of power storage, and the pipes beneath the water would be released when in need of energy release, where the strong buoyancy actuates the power generator and feeds the power to the grid. The team believes that this system is likely to become an affordable and high-efficiency energy storage system that can be paired with offshore wind farms in particular.

The team also believes that it is a powerful energy storage system. The cost of the existing leading energy storage system has become increasingly low, and the cost of the latest grid-level battery energy storage has lowered to US$150/MWh. BEST is not trying to replace battery, since the two energy storage systems possess somewhat different properties. BEST is able to store a sizeable degree of energy, whereas battery is capable of storing electric energy and responding to the need of the grid in a rapid manner. Julian Hunt, a researcher of IIASA, commented that the cost of existing battery energy storage systems is US$150/MWh, and about US$50-100 for BEST.

However, the installation cost of a battery energy storage system is still NT$4-8 million/MW (different also in maintenance cost) cheaper than that of BEST. IIASA believes that these two particular systems are able to co-store offshore wind power in oceanic islands or island countries, such as Japan, Australia, and the Philippines.

The team also pointed out that BEST can become an affordable hydrogen compression system and an energy storage system. The hydrogen within the pipes is already compressed when pulled into the sea owing to the relatively larger water pressure in the deep sea environment, which is why additional hydrogen storage tanks can be incorporated to float to the sea surface, or connect pipelines to infuse hydrogen.

Research personnel  commented that this method achieves 90% of efficiency in hydrogen compression, while onshore hydrogen compression equipment attains “nearly” 90% of efficiency. The investment cost of traditional compressors is also 30 times to that of seabed compression, and that is why the adoption of seabed compression will save an enormous amount of money.

 (Cover photo source: pixabay)