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Setting the Standard for Energy Storage System Performance

February 2015

Companies looking for an accurate method to gauge how well large batteries and other grid-scale energy storage systems work now have a new set of evaluation guidelines, called the Energy Storage Performance Protocol, at their disposal. The protocol serves as a starting point to draft standards by the International Electrotechnical Commission, the National Electrical Manufacturers Association, and the American Society of Mechanical Engineers. When completed, the standards will become the first-ever for measuring and reporting the performance of energy storage systems.

Official standards can take several years to develop and approve, but the protocol is expected to speed up the process. Developed by a working group of more than 100 stakeholders under the leadership of the DOE Office of Electricity Delivery and Energy Reliability and two DOE labs, Pacific Northwest National Laboratory and Sandia National Laboratories, the guidelines currently evaluate three energy storage performance uses:

  • Peak shaving: storing energy when power is abundant and discharging stored energy during times of high power demand
  • Frequency regulation: maintaining the power grid’s frequency at a constant 60 Hertz with frequent energy storage to balance power generation and demand
  • Islanded microgrids: small, self-sustaining power grids that generate enough electricity to power a home, neighborhood or town while being disconnected from the larger power grid

Several companies are already using the protocol when weighing whether or not to invest in an energy storage system. For example, Eos Energy Storage, a developer and manufacturer of grid-scale battery solutions, is using the protocol for in-house demonstration projects with customers.

"There are numerous use cases for energy storage on the electricity grid and there is a lot of confusion around how to determine best fit technologies for target applications," said Philippe Bouchard, Eos vice president of business development. "Having a standard testing protocol allows us to characterize performance in a manner that is uniformly accepted by the industry and our customers. This will help to determine the suitability of our product for specific applications and will accelerate market acceptance of new technologies on the grid."

The protocol is currently under revision and will be updated, initially in spring 2015, with three new applications:

  • Photovoltaic smoothing: evening out sharp power fluctuations that occur when passing clouds cause short-term changes in solar power generation.
  • Renewable firming/load following: making renewable energy more predictable by determining how much power on average can be available over the course of an hour
  • Volt/VAR control: keeping power traveling along the power grid within an acceptable voltage range so end users’ electric equipment can operate property and to reduce gradual power loss

The protocol is especially important as more and a greater variety of energy storage systems are being developed to enable the broader use of renewable energy. When adopted, the standards will still be voluntary, though more companies are likely to use them when they have gone through the official process. The protocol will continue to be revised as needed, with more metrics for existing applications added at the request of utilities who are considering using energy storage systems.

To learn more about the protocol, read the Fact Sheet on the DOE website.

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