While energy storage is a small fraction of total power generation capacity, promising examples suggest that distributed energy storage could change the electricity system during the next decade as fundamentally as distributed renewable energy has in the last decade.

Right now, 95% of energy storage in the U.S. is water pumped uphill into in reservoirs, but there are at least four applications that show how energy storage can complement renewables and offer more local control of the energy system.
Where Storage and Renewables Meet
As highlighted in a new report from the Institute for Local Self-Reliance, there are four areas where electricity storage is helping expand the use of distributed renewable energy.

  • Electric vehicles (EVs) – EVs provide an economical alternative to driving on petroleum fuel, and offer a broadly distributed method of storing grid electricity for future use. While the vehicle-to-grid technology needed to make energy storage practical is not widely in use, many EV owners already look at combining their vehicle with solar on their home to double-down on shrinking their carbon footprint.
  • Community solar – one electric cooperative in Minnesota is using battery storage with its community-based solar array to meet local energy demand. In the future, this may also provide additional revenue, and increase the potential scale of local solar projects.
  • Island power grids – using energy storage, modeling remarkably high penetrations of variable renewable energy (40% and higher), island grid energy storage can maintain reliability and the match between supply and demand.
  • Microgrids – localized power systems can reduce costs, increase reliability, and scale up renewables, made possible by combining local energy production and storage.

Energy Storage Technology and Uses
Over 95% of deployed energy storage is in the form of water stored in hydropower reservoirs. But new, promising technologies are being commercialized to support distributed renewable energy and meet the reliability and quality needs of the electricity system, along with many decades-old technologies.  Energy storage is divided into many technologies within 4 different media.

Energy storage can serve a number of important roles on the electricity grid, much more than simply storing daytime solar electricity for nighttime use, for example.

Uses for energy storage include:

  • Managing Supply and Demand – energy customers can reduce their bills by shifting energy use to low demand periods or by reducing their maximum
  • energy use in a given month. Energy storage can cost- effectively supply capacity and backup power that has historically been provided by expensive quick- response fossil fuel power plants.
  • Delivering Ancillary Services – at every moment supply and demand of electricity must be in balance. Energy storage can respond more quickly than most existing technologies, helping maintain the voltage and frequency of the electricity system to avoid damage to connected electronics and motors, and avoid power outages.
  • Reinforcing Infrastructure – power lines, transformers and other grid infrastructure wears more quickly when operating at peak capacity. Energy storage can shift energy demand to ease stress on expensive equipment. It also allows energy users to manage their own energy use.
  • Supporting Renewable Energy – renewables are often variable, and variable energy can be challenging for inflexible utility power plants to accommodate. Energy storage responds quickly and effectively to variations in renewable energy output, enabling higher penetrations of wind and solar on the electric grid.

The different technologies for energy storage vary in their ability and cost-effectiveness to provide these services. The forms of potential energy provide the best bulk storage of electricity, but the other forms can be more nimble and meet needs for fast response.
How Energy Storage Can Grow
Three factors mentioned in the report suggest that energy storage is on the cusp of greater growth:
1. Falling costs will permit utilities to use storage to more efficiently integrate high percentages of renewable energy;
2. Electric vehicle use will continue to grow quickly as a cost-effective alternative to petroleum fueled vehicles; and,
3. Businesses, individuals, and other entities will seek more control over their energy system, enabled by energy storage.

Energy storage will also change the political dynamic of local renewable energy development. Utilities that have tried erecting barriers to on-site power generation may find that cost-effective energy storage enables their customers to leave the grid. Although most will not leave, the option to defect (described in a recent Rocky Mountain Institute report) will give electricity customers unprecedented leverage and control over their energy future.

Photo Credit: Pete Slater