The market for grid energy storage is robust and growing. According to a study published by GTM Research, the U.S. market for utility-scale grid storage is expected to rise from an annual value of about a quarter of a billion dollars in 2009 to about $2.5 billion by 2015.
The potential exists for continued rapid growth in this market in the United States and worldwide. Demand will be filled by companies pursuing a variety of technologies to fill the needs of the power grid.
What is Grid Energy Storage?
In an ideal energy world, the demand for electric power would be matched exactly by electric power supplied, with no need for backup power sources or storage anywhere in the grid. But, in the real world, demand and supply are often mismatched.
Demand for electric power varies by time of day and changes with every season. Power supply varies based on many factors, including plant downtime, changes in fuel supply and prices, and the intermittent nature of renewable energy sources such as wind and solar.
The imbalance between demand and supply is evened out by various technologies that store energy and make it available to the grid as it is needed. With the rise of the “smart grid” and the increasing importance of renewable energy sources, the demand for grid energy storage and the complex technologies that supply it are large and growing.
Sources of Grid Energy Storage
There are numerous technologies already available or being developed for supplying reliable and economic grid storage. Batteries and pumped hydro systems are among the most mature grid storage technologies.
Batteries can store excess electricity from wind and solar plants for distribution to the grid when it is dark or the wind stops blowing. One strategy on the drawing board is to use electric cars as sources of grid energy while they are plugged in at night for recharging.
Pumped hydro systems use excess generating capacity during off-peak hours to pump water uphill for later release through turbines to generate electricity during peak demand periods.
Other technologies at varying stages of research and commercialization include flywheels, compressed air storage, superconducting magnets and ultra-capacitors.
Interfacing with the Grid
With each of these energy storage technologies comes the need to be able to store and return the energy to and from the grid as needed. Grid-Tie Inverters (GTI) or Active Front End (AFE) power converters are typically used to provide this function. Advanced digital control solutions such as the OZGTI-3000 can be used to implement custom OEM solutions for this power conversion application.
Each grid storage technology has costs and benefits. The grid of the future will use a combination of several of them for maintaining the crucial balance between supply and demand.
Photo by kevin rigdon.