The increasing regulatory push worldwide for renewable energy as well as a rise in demand for clean energy from corporate and individual consumers have now brought a lot of attention on large-scale storage of energy. The most popular forms of renewable energy generation- wind and solar require that energy be stored when the generation is high (which may not coincide with high demand for electricity) and be released into the grid when there is demand. As more are more nations target a higher percentage of renewable or clean energy in the next two decades, how far these targets would be met would depend to a large extent on the development of cheap means of large-scale energy storage. We will have a look at 5 promising technologies in grid-scale energy storage that could answer this all-important question.
Pumped Hydro Storage
Pumped hydro storage currently accounts for 90% of the world’s grid energy storage capacity. It uses surplus power generated to pump water up to a reservoir behind a dam. The stored water is then released through turbines to generate electricity when the demand for electricity is high. A recent study by Australian National University has identified 530,00 potential sites for pumped hydro energy storage worldwide, these sites that could be linked with solar or wind power generation systems to create grids that are fully sustainable.
Lithium-ion Batteries
Li-ion batteries dominate the consumer electronic, electric vehicle battery markets and are also being used successfully in grid-storage. The chief advantages being high energy density, low self-discharge, and low maintenance. The continued interest and R&D in Li-ion batteries has driven the price per kilowatt-hour to less than one-tenth of what it was a decade ago. Tesla’s Powerpack for commercial and grid applications make use of Li-ion battery technology for peak shaving, demand response, voltage control, and as a backup power reserve. The top manufacturers of Li-ion batteries globally by storage capacity are LG Chem, CATL, BYD, Panasonic and Tesla.
Vanadium Redox Batteries
In redox flow technology, electrodes are replaced by two tanks filled with electrolytic fluids with different oxidation levels, the electrolytes are then pumped through membranes that divide negatively and positively charged protons in different tanks. The most popular kind of redox flow battery is a Vanadium-flow battery. The advantage of redox flow batteries over Li-ion batteries is that they are more scalable, have a much longer operating life, are easier to 
maintain and perform much better when it comes to heat generation. By increasing the size of the electrolyte storage tanks, the energy storage capacity of redox flow batteries can theoretically be increased without limit, perfect for grid-scale operations. The global leaders in Vanadium Redox Flow batteries include Avalon Battery, UniEnergy Technologies, Rongke Power, Sumitomo Electric.
Flywheel Energy Storage
Flywheel energy storage systems function by converting electricity to mechanical energy in the form of rotational kinetic energy. Electricity is used to accelerate a rotor to a high speed and the power is maintained as rotational kinetic energy, the energy can be drawn from the system when required and the flywheel rotational speed is reduced. When energy is again introduced into the system, the rotor is accelerated. ABB has successfully integrated a flywheel energy storage system in an isolated micro-grid in the Alaskan island of Kodiak.
Compressed Air Energy Storage
Compressed air energy storage (CAES) plants use excess electricity generated during low-demand periods to pump air to be stored under high pressure underground. This pressurized air heated and used to rotate a turbine to generate energy again. The first utility-CAES project was the 290 MW Huntorf plant in Germany. Since then the scale and the storage efficiency of the technology have improved significantly.
Which of these technologies will be at the forefront of large-scale energy storage, or will it be something new? With the rising demand for renewable energy and global sales in electric vehicles projected to keep going up, it definitely is exciting times ahead for energy storage technologies. The virtual conference, Energy Storage and Battery Solutions during the 2020 crisis bring together experts and decision-makers from leading energy and technology companies in Europe to discuss the latest technologies and explore opportunities and developments in energy storage. Connect with us to join the discussion.
