Energy storage is a compelling complement to wind and solar, because of high flexibility and ability to operate as both load, when it charges, and generation, when the energy is deployed. Energy storage addresses many of the challenges to grid operators providing safe and reliable electricity for customers, and due to rapidly declining costs, performance improvements of lithium-ion batteries and an emergence of “grid-ready” energy storage products, commercially viable grid energy storage has now arrived, in certain applications. As energy storage becomes more widely available and economically feasible, it may make renewable generation, when paired with energy storage, a more viable option to provide reliable electric generation – and load demand – service in more areas of the world.
Storage anywhere
Energy storage can be deployed everywhere in the power grid, connected to transmission (T), distribution (D), or on customer-side of the meter. Storage may be co-located with renewables, conventional generation, loads, or it may be standalone.
Energy storage connected to the end customer could potentially address services upstream to support distribution, transmission, and generation functions, because its dispatch also propagates upstream. In contrast, a transmission-connected system typically cannot provide downstream services. Larger systems take advantage of economies of scale, which may offset access limitations for certain value streams.
Is that cycle worth it?
Service stacking comes with the costs and complications of multiple, potentially competing, commitments, which may also increase the wear and tear on energy storage systems. When designing an energy storage project, it is important to understand the value and associated requirements for each service addressed. Energy storage is still a relatively expensive resource, so excessive sizing or operation without an associated payback may cause a potential project to become uneconomic.
A common and desirable use of energy storage is often called peak shaving i.e. reducing the amount of power drawn from the grid beyond a specified limit. This typically maps to more precise services, such as resource adequacy (i.e. peaker plant substitution) or transmission or distribution upgrade deferral (i.e. non-wires alternatives). The sizing, availability, and location of energy storage for these services is critical, but the required dispatch may be infrequent when the grid is under stress, to achieve the desired benefit of deferring or avoiding an alternative major capital investment.
Other services, such as spinning and non-spinning reserves, may also be desirable with energy storage with very low operating costs because they essentially require energy storage to act as a reserve with no dispatch. Energy storage may also be able to offer these services while charging, by committing to stop charging if needed.
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