Energy storage technology provides flexibility to support renewable energy expansion and meet net-zero goals. Battery energy storage, which converts chemical energy directly to electricity, has emerged as one of the more popular large-scale solutions, while other storage methods may include compressed air, superconducting magnets or underground pumped hydroelectric storage.
Energy storage technology can also be utilized to help avoid price surges during periods of high demand, providing consumers with more savings while protecting the environment.
Battery
A battery stores chemical potential energy as positively charged ions within its electrolyte, and when connected to an external circuit these ions move between its electrodes in an electron tug-of-war that generates electricity.
At a grid scale, batteries provide backup power during an unexpected power outage and enable renewables to be dispatched when most needed – helping stabilize the electric grid, lower emissions and facilitate electrification to meet Net-Zero goals.
To meet its job, batteries must charge and discharge quickly, using high voltage to quickly move ions through their cells and large capacities for storage. A battery’s design and materials determine its rated power, duration and energy capacity – it’s crucial that consumers understand these terms when comparing batteries; one simple formula would be: Power = Voltage * Current.
Flywheel
Flywheels were once ubiquitous in engines and machines, but are making a comeback as power system components. Their purpose is to store kinetic energy – the mechanical energy associated with movement – for use later.
Flywheels are supported in vacuum chambers by magnetic bearings with low frictional losses to store energy for later use by an electrical machine that turns it. When required for energy storage or use by systems, these rotors can be turned with electrical machines that transform kinetic energy to electricity before applying it directly to them.
This approach creates a more consistent flow of power from renewable sources like wind and solar power that produce intermittent electricity outputs. Furthermore, this solution is often combined with batteries for quick bursts of power when needed.
Thermal
Thermal Energy Storage (TES) utilizes grid or onsite electricity to store heat either in an insulated medium or chemically bound forms, decoupling its availability from users’ needs, giving them lower prices and greater efficiencies through existing facilities.
TES uses standard cooling equipment with energy storage tanks to shift all or a portion of an air-conditioning system to off-peak, night time hours when electricity rates are significantly reduced. Ice banks that contain non-chemical phase changes, like those used as energy storage heat packs among skiers, also fall under this category of storage heat packs.
Long duration thermal storage deployment has been hindered by current rate design, which gives TES systems access to only wholesale or marginal pricing of electricity. To level the playing field for TES systems, Antora’s Noah Long has proposed reforms that may help level it in his RTC/LDES Council report.
Hydrogen
Hydrogen can be stored as a gas and used in fuel cells to produce clean electricity without carbon emissions or harmful emissions. Refueling hydrogen makes it ideal for transport applications like buses, trucks or ships that cover long distances in one tank of energy.
An extensive review was performed of 15 real-world projects using hydrogen technology for energy storage (full-scale and test/pilot systems), categorizing them by topology (grid connected or standalone off-grid systems), storage method (“CG”: compressed gas storage; “MH”: metal hydrides storage), objectives such as power ramping capability and load shedding and topology (grid connected/standalone off grid systems).
Operational data revealed that optimal energy conversion efficiency was reached when both electrolyser and fuel cell operated at their designated power levels while battery handled rapid power fluctuations, with this strategy significantly decreasing electrolyser power requirements and prolonging fuel cell lifespan [38]. Furthermore, hybridization with additional storage technologies such as batteries or supercapacitors proved essential to both improving overall system efficiency and longevity [40-43].