Energy shifting involves storing electricity in the energy storage system for use at a later, pre-specified time. This bulk energy can be discharged during periods of high demand on the grid, whether by high pricing to sell energy back onto the market or charging in periods of lower-cost energy and then using that energy during higher-cost periods to support load. This is a common potential application for C&I customers to arbitrage electricity rates.

Coupling energy shifting with a renewable, such as rooftop solar or a co-located solar site, allows leveraging of time-of-day pricing. It can also optimize electricity consumption and defer investment for grid upgrades in cases where existing infrastructure may not be able to support long charging periods, such as EV roadside charging. In these cases, energy can be shifted overnight to use during the day to supplement the grid power.

Peak shaving is similar to energy shifting, but the main driver is to reduce peak demand to ultimately reduce the electricity bill or make operations more economical. Peak shaving is typically applied when the energy storage system is owned by the electricity consumer, rather than by the utility. The goal is to avoid demand charges (power fees) and the installation of capacity to supply the peaks of a highly variable load.

As with energy shifting, peak shaving reduces electricity bills and helps defer grid upgrades. Peak shaving using an energy storage system can be applied to EV charging, as well, especially when using a high-power charger.

Frequency regulation, reserve, and response is when the energy storage system is charged or discharged in response to the frequency on the grid, such as when maintaining a frequency within a certain dead band or following a signal-driving frequency. This approach to frequency regulation (fast frequency response) is a particularly attractive option due to its rapid response time and emission-free operation and can be used to support existing generation assets or as an ancillary service.

For example, solar farm installation regulations might require the frequency at point of interconnection to be within a predefined dead band, leading to solar developers installing energy storage systems that would drop frequency quickly and temporarily at the point of interconnection, in the event of passing weather conditions such as a dark cloud moving over the panels.

As generation decentralizes and the industry shifts to renewable assets that produce intermittent energy, electricity generation can be turned up or down and dispatched by a grid operator. Capacity firming allows the variable, intermittent power output from a renewable power plant, such as wind or solar, to be maintained at a committed level for a period of time.

Digitization plays an important role. Using built-in parameters, the energy storage system smooths out the power, so the grid sees consistent rather than intermittent energy, making it easier to manage.

In a spinning reserve application, energy storage systems can respond within milliseconds and supply power to maintain network continuity, while the backup generator is started and brought online. This enables generators to work at optimum power output, without the need to keep idle capacity for spinning reserves. This eliminates the need to have backup generators running idle. To provide effective spinning reserve, the energy storage is maintained at a level of charge ready to respond to a power failure. Often, cost and CO2 emission savings are easy to quantify in cases where spinning reserve is applied.

Spinning reserve is a reliable first step in displacing diesel generators. While working groups are researching long-duration storage technology, ABB currently recommends against replacing a full diesel generator or system with an energy storage system. Complete diesel generator replacement is possible from an energy supply standpoint, but not economical.