Energy Storage, Applications and Technologies
Dr. Imre Gyuk, Program Manager, Energy Storage Research, U.S. Dept of Energy
The merits of energy storage have come increasingly recognized during recent years. Already some 2.5% of U.S. electricity passes through storage in the form of pumped hydro. But 10% in Europe and some 15% in Japan provide much more substantial grid stability. As technology becomes increasingly digital and greater power quality is needed, storage devices, which can provide seamless continuity, are becoming an indispensable necessity. On the grid, fast energy storage can provide frequency and voltage regulation, which is twice as effective as regulation by fossil fuel generation and has a carbon footprint reduced by 70%. Storage can provide deferral of substation or distribution upgrade. As the electric load grows and generation and transmission fail to keep pace, management of peak load become an important task for storage. But the most serious role for storage arises from increasing penetration of intermittent renewable generation. Since fluctuations will now come from both the load and the generation side, regulation will need to be considerably increased. In addition, sudden ramping, particularly from wind, will have to be accommodated. Finally, wind in many parts of the U.S. is anticorrelated, so that available power at night time is often greater than the load. The resultant negative electricity prices impose a severe burden on both fossil and renewable generation. Energy Storage, along with demand response and distributed generation, has an essential role in all these applications. A portfolio of storage technologies, including advanced batteries, flow batteries, supercapacitors, and flywheels, is available to address applications in the tens of MW range. For larger applications, pumped hydro and compressed air energy storage (CAES) offer a good fit. While there are only two CAES plants currently in existence, there is considerable interest in establishing new plants. Funding available through the American Recovery and Reinvestment Act can be expected to result in many new and sizable storage facilities in the near future.