Ongoing Project: Mechanical Energy Storage
Developing advanced energy storage lab, focusing on compressed air energy storage and buoyancy work energy storage technologies. Both are mechanical energy storage technologies and offer a viable alternative to electrochemical batteries
Compressed air energy storage (CAES) uses excess energy to operate a compressor that stores air at high pressures (200-300bar). Once the demand for energy rises, air is discharged from the tanks into an air motor that is coupled with an AC generator that delivers the electricity back to the grid or to loads off grid.
The compressed air energy storage system is modular, and can be expanded by controlling the number of interconnected tanks
Utilizing expansion cooling as an ancillary process to compressed air energy storage for refrigerant-less cooling applications (e.g. data centers). This can be accomplished by adding heat exchangers to the outlet of the compressor to remove heat that is routed to an adsorption chiller, while the expanding air that needs to be heated in order to be admitted to the air motor will result in a large capacity chilling effect (expansion cooling) that can be used for air conditioning or for cooling of data centers while also providing energy storage.
Using additive manufacturing technologies to produce compressed air energy storage equipment such as vaned air motors and AC generators.
Vaned air motors can be 3D printed while optimizing their size, number of blades, blades shape and size. The experiments center around retrofitting the air motor on existing AC generators, while research is being done on using fully 3D printed motors and generators.
Buoyancy work energy storage
Another mechanical energy storage technology that follows the simple Archimedes floatation principle. When demand is low, excess energy is used to submerge a buoy filled with air in water via a motor with a tether wound around a pulley. The buoy is anchored and remains under water until demand is high, at which point it is released and allowed to ascend, unwinding the tether and rotating the electric generator, and hence converting the potential energy into kinetic energy and eventually electrical energy.
The cycle then repeats between high and low demand. The variables include the buoy volume, inflating gas, host fluid as well as the friction interaction between the buoy and the liquid. The energy density is a function of the height/depth that the buoy has to complete the ascension.
At left: System charged (buoy at bottom position)
At right: System discharged (buoy at top position)