Future Energy Storage Technologies for the Grid

Bradford Roberts, Chair, Electricity Storage Association and Power Quality Systems Director, S & C Electric Company, provided a compelling discussion on energy storage technologies for the grid of today and tomorrow. He began his discussion with an interesting point, arguing that we all need to remember that the electricity industry is the only major industry that tries to operate with no inventory. Indeed, if we were to stop generating electricity right now, all of the lights would go out instantaneously. This is in contrast to a brick-and-mortar industry in which, if supply is cut there would still be inventory on the shelves likely able to last through the shortage.

A way to overcome the grid’s lack of inventory is through the deployment of storage technologies. There are many grid storage alternatives and Roberts presented a summary of a few: (1) pumped hydro, which is currently the biggest contributor to storage (in fact, current pumped hydro storage actually exceeds renewable energy capacity in the industry); (2) compressed air storage, which uses geological caverns and empty spaces underground to store compressed air (in a similar manner to pumped hydro which stores water); (3) batteries, which are developing at unprecedented rates with new technologies such as the Vanadium Redox (VBR), Zinc Bromine, and Zinc Flow Battery systems; (4) flywheel systems; and (5) power conversion systems.

These storage systems work most ideally in combination with renewable energy technologies such as wind power. Unfortunately, according to Roberts, the wind power capacity factor in the US is only about 25-27 percent. To tackle this problem, the US needs to undertake projects such as that recently completed in Japan where a 34 megawatt battery was connected to a 51 megawatt wind farm, allowing the wind farm to be 100 percent dispatchable during peak hours every single day.

Roberts has been very active in this field and pointed the audience to a report recently completed by the Electricity Advisory Committee, on which he is a member, entitled Bottling Electricity: Storage as a Strategic Tool for Managing Variability and Capacity Concerns in the Modern Grid.