Utilities ponder battery storage as solar soars

SAN FRANCISCO – Growing electricity generation from by solar and wind energy is flowing into California’s electrical grid, forcing utilities here to begin integrating energy storage technologies into their systems as they seek to offset the peak midday energy generating capacity of these “intermittent renewables” with peak late afternoon energy usage.

While traditional “bulk storage” techniques like pumped hydro and compressed air remain the most cost-effective storage methods, utility executives and market analysts at the Intersolar North American conference here said promising storage technologies like zinc bromine flow batteries are being demonstrated on the grid and in utility substations. Persistently high battery costs continue to slow adoption, however.

While next-generation battery technologies like lithium ion remain too expensive for utilities, Mark Rawson, senior project manager for Sacramento’s Municipal Utility District, said technologies like zinc bromine are approaching the $400/kWh price point utilities need to begin widespread deployment of the storage technology.

While lithium ion remains one of them most promising battery technologies, it remains expensive and unproven for grid storage applications. Besides cost, the big question for utilities is whether lithium ion batteries will be “durable and reliable,” Rawson said, adding that automotive applications will likely show whether lithium ion batteries are sufficiently robust for mission-critical power grid applications. If the technology is widely adopted in electric vehicles, for example, Rawson said the resulting scaling would help reduce battery costs below the $400/kWh barrier.

The Sacramento utility is participating in several photovoltaic storage demonstrations, including a Energy Department-sponsored project with lithium-ion battery specialist A123 Systems. For now, Rawson said, “The market still has to develop to bring down lithium-ion battery costs.”

Renewable energy analysts here agreed, but argued that lithium ion and other storage technologies hold great promise as utilities search for reliable storage technologies that would allow them to use greater quantities of electricity produced by solar photovoltaics (PV).

The solar industry is currently shifting from the electricity generation phase to a new “integrated energy” phase in which renewable energy sources are being consumed where they are produced rather than transmitted to other parts of the grid, said Daniela Schreiber, an energy analyst with Germany’s EuPD Research.

“We are currently experiencing the dawn of a new era – PV 2.0,” Schreiber argued, an incremental step in which storage technologies are decentralizing the power grid and allowing consumers to directly consume power produced by photovoltaics.

Schreiber added that the integration of storage technologies into power grids also creates opportunities for new market entrants providing new power electronics and control hardware and software needed to integrate storage technologies into power grids.

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