U.S. policymakers must focus more closely on developing new energy storage technologies as they consider a national renewable electricity standard, according to one of the principal recommendations in a newly released report, Integrating Renewable Electricity on the Grid, by the American Physical Society’s Panel on Public Affairs (POPA).

The report notes that as renewable generation grows it will ultimately overwhelm the ability of conventional resources to compensate renewable variability, and require the capture of electricity generated by wind, solar and other renewables for later use. Transmission level energy storage options include pumped hydroelectric, compressed air electric storage, and flywheels. Distribution level options include: conventional batteries, electrochemical flow batteries, and superconducting magnetic energy storage (SMES). Batteries also might be integrated with individual or small clusters of wind turbines and solar panels in generation farms to mitigate fluctuations and power quality issues.

According to APS, cnergy storage for grid applications presently lacks sufficient regulatory history. Energy storage on a utility-scale basis is very uncommon and, except for pumped hydroelectric storage, is relegated to pilot projects or site-specific projects. Some states such as New York categorize storage as “generation,” and hence forbid transmission utilities from owning it. In addition, utilities do not know how investment in energy storage technologies will be treated, how costs will be recovered, or whether energy storage technologies will be allowed in a particular regulatory environment.

Another challenge facing the grid involves the long-distance transmission of renewable electricity from places that receive a lot of wind and sun to those that do not. “We need to move faster to have storage ready to accommodate, for example, 20 percent of renewable electricity on the grid by 2020,” said George Crabtree, co-chairman of the POPA study panel and a senior scientist at Argonne National Laboratory. “And, by devoting the necessary resources to the problem, I am confident that we can solve it.”

The report addresses variability and transmission issues by urging the U.S. Department of Energy (DOE) to increase research on materials to develop energy storage devices and by encouraging the DOE to focus on long-distance superconducting direct current cables to bring renewable electricity to load centers, lessening the chance that power will be disrupted. The report also calls for examining renewable electricity in light of a unified grid instead of one that is fragmented and improving the accuracy of weather forecasts to allow for better integration of renewable electricity on the grid.

The APS report says the DoE should develop an overall strategy for energy storage in grid-level applications that provides guidance to regulators to recognize the value that energy storage brings to both transmission and generation services on the grid. The DoE should also conduct a review of the technological potential for a range of battery chemistries, including those it supported during the 1980s and 1990s, with a view toward possible applications to grid energy and storage. Another recommendation is that the DoE should increase its research and development in basic electrochemistry to identify materials and electrochemical mechanisms that have the highest potential use in grid-level energy storage devices.

The American Physical Society is the leading physics organization, representing 48,000 members, including physicists in academia, national laboratories, and industry in the United States and internationally. APS has offices in College Park, MD (Headquarters), Ridge, NY, and Washington, DC.