Grid energy storage is a critical component in the modernization of the electricity system and the development of smart grids with increasing levels of renewable generation, but there are several challenges to its widespread deployment, a new report from the U.S. Department of Energy finds.

Currently in the U.S. there is about 24.6 GW of grid storage, with about 95% of it as pumped storage hydro, due to its larger unit sizes and longer history as the technology of choice. This is approximately 2.3% of total electric production capacity, and is a lower fraction than in Europe or Japan. In order to achieve 20% renewable generation by 2020 some 18.6 GW of intra-hour balancing will be required for grid stability, of which at least 5 GW from energy storage would be reasonable.

The report identifies four principal challenges related to the widespread deployment of energy storage. These are the development of cost effective energy storage technologies, validated reliability and safety, an equitable regulatory environment, and industry acceptance.

Some of the key strategic actions to meeting these challenges are:

  • Cost competitive energy storage technology can be achieved through research, resolving economic and performance barriers, and creating analytical tools for design, manufacturing, innovation and deployment.
  • The reliability and safety of energy storage technologies can be validated through research and development, creation of standard testing protocols, independent testing against utility requirements, and documenting the performance of installed systems.
  • Establishing an equitable regulatory environment is possible by conducting public-private evaluations of grid benefits, exploring technology neutral mechanisms for monetizing grid services, and developing industry and regulatory agency accepted standards for siting, grid integration, procurement and performance evaluation.
  • Industry acceptance can be achieved through field trials and demonstrations and use of industry-accepted planning and operational tools to incorporate storage onto the grid.

“Energy storage is a vital component of a more resilient, reliable and efficient electric grid,” said Energy Secretary Ernest Moniz. “We must continue developing innovative energy storage technologies and finding new ways to ensure wider adoption to help move the nation closer to the grid of the future.”

DOE’s targets for storage development include achieving a system capital cost for AC energy storage systems under $250/kWh, levelized cost under $0.20/kWh/cycle and system efficiency over 75% in the near term, and system capital cost under $150/kWh, levelized cost under $0.10/kWh/cycle and system efficiency over 80% in the long term. Such AC energy storage systems would include redox flow batteries, sodium-based batteries, lead-carbon batteries, and lithium-ion batteries, among other technologies.

The report, Grid Energy Storage, was commissioned at the request of the Senate Energy and Natural Resources Committee and reviews the status and benefits of storage technologies and details DOE and other storage activities in the U.S.

View the report HERE.

By Jonathan Spencer Jones