This summer American Electric Power (AEP) became the first electric utility in the nation to deploy a community energy storage (CES) system in its service territory. AEP’s CES system consists of 80 25 kW units, which were installed in a residential neighborhood in Columbus, Ohio. NAATBatt member firms S&C Electric and International Battery supplied the storage units and the lithium-ion batteries that the first units contain.
The launch of the first CES system is a watershed in the history of grid-connected electricity storage in the United States. Although the U.S. Department of Energy and electric utilities nationwide continue to investigate different ways to store electricity on the grid, many industry experts are coming to the view that CES will be the “killer app” in grid-connected energy storage.
The attractiveness of CES systems does not lie in their cost. On a pure cost per kilowatt basis, it is cheaper to store electricity in bulk, using pumped hydro storage, compressed air systems or multi-megawatt flow batteries, than in hundreds of small 25-100 kV units installed in basements or buried in residential neighborhoods around the country.
But cost per kilowatt is not a valid basis for evaluating storage systems. Storage is not an objective itself; it is a means to an end. Storage serves the same end as all other grid infrastructure: providing safe, reliable electric power to consumers at the lowest possible cost. Judged by this metric, CES systems may have a leg up on their nominally cheaper storage and peak generation technology competitors.
The advantage of CES systems lies in their ability to provide multiple benefits to electricity customers and to the utilities that serve them. Because CES systems are located immediately proximate to the ultimate customer, they can provide back-up power, level peak loads and reduce the strain on, and necessary investment in, the complicated and often unsightly infrastructure needed to distribute centralized electric power. CES systems can facilitate the deployment and rational net metering of distributed solar and wind electricity generation and support the recharging of electric vehicles on demand. In addition, hundreds of CES units can be networked by utility operators to provide the same sort of transmission support and leveling of variable renewable energy generators that larger storage facilities and peak generators can provide.
The small size and low individual cost of CES units is also an advantage. Individual units are relatively inexpensive and can be deployed by ordinary utility work crews. Their deployment does not require complicated permits, environmental impact statements or dedicated maintenance resources. Bulk storage units and peak generators can take years to permit and deploy; CES units can be deployed as part of a utility’s ordinary capital improvement program.
The greatest advantage of CES systems, however, may be that their ability to provide back-up power is a benefit that can easily be explained to, and appreciated by, ordinary electricity customers. Ordinary consumers suffer tens of millions of dollars of damages each year due to power outages. Those who cannot afford or cannot deploy costly private back-up generators suffer disproportionately.
At the time the grid was designed, the impact of outages was generally shared and grudgingly accepted. There was no feasible technological fix. Today, however, there is, in the form of CES systems. Grid-connected energy storage will become a reality in the United States when consumers start demanding from their utilities and PUC’s the type of electricity reliability that 21st Century CES systems can provide. When they do, CES systems will lead the way in deploying energy storage technology on the grid.