Utilities weigh battery storage option for solar energy

Renewable energy from solar and wind sources are flowing into California's electrical grid, forcing utilities 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 common "bulk storage" techniques, such as pumped hydro and compressed air, remain the most cost-effective storage methods, utility executives and market analysts at the Intersolar North American conference have declared that promising storage technologies, like zinc bromine flow batteries, are being demonstrated on the grid and in utility substations. However, high battery costs still hinder the adoption of these storage methods.

Mark Rawson, senior project manager for the municipal district of Sacramento, stated that although next-generation battery technologies, such as lithium ion remain too expensive for utilities, technologies like zinc bromine have approached the $400/kWh price point which utilities need to begin widespread deployment of storage technology.

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

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

Although renewable energy analysts agreed with Rawson, they also argued that lithium ion and other storage technologies hold great promise as utilities search for reliable storage technologies that would allow greater quantities of electricity to be produced by solar photovoltaics (PVs).

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.

According to Daniela Schreiber, energy analyst with Germany's EuPD Research says that there is an ongoing shift from the electricity generation phase to a new "integrated energy" phase. Renewable energy sources are being consumed where they are produced rather than transmitted to other parts of the grid.

"We are currently experiencing the dawn of a new era – PV 2.0," argued Schreiber, 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 could possibly create opportunities for new market entrants providing new power electronics and control hardware and software needed to integrate storage technologies into power grids.

- George Leopold
?? EETimes US