Grid energy storage refers to a collection of methods used to store large amounts of energy within a power grid. Energy is stored when electricity is abundant and cheap (especially from intermittent power plants such as wind, tidal, solar, and other renewable sources) or when demand is low, and then returned to the grid during times of high demand when prices are typically higher.
Any power grid must balance the amount of electricity generated with the amount consumed, and both will undergo enormous changes over time. Any combination of energy storage and demand response has the following advantages:
Fuel-based power plants, such as coal, oil, natural gas, and nuclear energy, can operate more efficiently and easily at a constant production level.
Electrical energy produced by intermittent sources can be stored and used later, or else it must be transmitted elsewhere for sale or shut down.
Grid power storage can reduce peak generation or transmission capacity by using all stored potential plus delayable loads, thus saving the cost of this capacity.
More stable pricing, with the cost of storage or demand management included in pricing, leads to smaller changes in the electricity price charged to customers, or (if prices are legally stable) less expensive imports of wholesale electricity that would otherwise cause losses to utilities during high-demand peak periods.
Grid power storage can serve as emergency preparedness, which can reliably meet critical demand even without transmission or generation and delay non-necessity demand.
Renewable energy from sources like solar, tidal, and wind energy varies and produces volume of electricity that changed by random factors like time of day, phase of the moon, season, and weather. Therefore, the lack of storage for renewable energy presents special challenges to power companies. While connecting many individual wind sources can reduce overall variation, solar energy cannot be used at night, and tidal energy moves with the moon, causing significant impacts on any given utility.
In the summer, when electricity consumption is high, more solar energy can be absorbed and matched with demand. In winter peak hours, wind is associated with heating demand to a lesser extent and can be used to meet that demand. Based on these factors, intermittent sources of energy (such as solar and wind turbines) connected to the grid often require investment in grid power storage or demand-side management that exceeds 20% to 40% of total electricity generation capacity.
