Taking Grid Energy Storage to the Edge

http://www.renewableenergyworld.com/rea/news/article/2010/05/taking-grid-energy-storage-to-the-edge

The concept of storing electricity generated in a utility grid has been tried since the beginning of the power industry. In the U.S., large-scale storage projects flourished in the 1960s, '70s, and '80s as utilities added 18 GWs of pumped hydro facilities to support the rapid build out of the fleet of nuclear power plants across the nation. Nuclear plants run best at higher power ratings, so pumping water in these hydro plants presented ideal off-peak loads during nights and weekends when customer demands are lowest. This method of grid storage has been improved during the past two decades, and today these plants provide more than 2 percent of the total capacity of the national grid.

Now, as the grid faces a rapidly growing component of renewable energy sources (wind and solar), the job of balancing generation sources and load demands is becoming more challenging. With most regions of the U.S. trying to achieve renewable portfolio standards (RPS) of 20 to 30 percent in the next 10 to 20 years, stable and reliable control of grid voltage will be a bigger task for utilities and system operators. Utilities and regulators know they must deal with this, and major changes are in the works.

The biggest steps started in 2009 with massive stimulus investments by the U.S. Department of Energy (DOE) to accelerate the development of smart grids throughout the nation. Demonstration projects totaling more than $1.6 billion were announced with implementation occurring in 2010 and 2011. The projects cover every aspect of smart grid technology, from intelligent meters in homes to automation of distribution circuits to energy storage devices such as flywheels and batteries at different levels of the distribution network.

Battery Power in Substations

Starting five years ago, American Electric Power (AEP) took the lead in determining the value of adding fairly large amounts of battery energy storage in substations. The distributed energy storage system (DESS) approach was used to test peak load management and improvement of system reliability by deploying systems in sizes of 2 MW with seven hours of support time. Figure 1 shows one of the systems installed in an Ohio substation.

<more>