Available Technology

Modular Electromechanical Batteries for Storage of Electrical Energy for Land-Based Electric Vehicles

The Laboratory has several decades of experience in the development of EMBs. In the course of this development several prototypes that advanced the technology were constructed and their designs were licensed. Work is now underway at the Laboratory to develop new types of EMBs with the objective of bulk storage of electricity at utility scale. This new generation of modular flywheel storage systems is based on the use of some special technologies, including passive magnetic bearings and a novel type of electrostatic generator that is very light in weight and, since it has near-100 percent efficiency, does not require active cooling. In these respects these new designs differ greatly from present commercially available flywheel storage systems. As noted above, the purpose of this FBO is to make U. S. Industry aware of an opportunity to participate in the development of EMBs specifically designed for vehicular use. With minor exceptions, at present all electric vehicles are powered by electrochemical batteries, with their well-known limited deep-discharge cycle life and modest electrical turnaround efficiency (70 to 80 percent). Electrochemical batteries in principle could continue to fill the storage demands of electric vehicles, but they fall short in three areas. The first is their limited cycle life under deep discharge conditions. Despite many decades of development the best of such batteries typically have a deep-discharge cycle life of about 1000 cycles, requiring operation under restricted depths of discharge to achieve multi-year lifetimes. Second, the "turnaround" energy efficiency of electrochemical batteries, being typically of order 80 percent, lowers the overall energy efficiency of the vehicle. It also limits the efficiency of regenerative braking, a technique that is important in increasing the range of the vehicle per kWh in its battery pack. Third, the electrochemical batteries in present use carries with them problems of overheating and catching on fire, and also involve the disposal of hazardous waste, problems that are not an issue with the EMB. The New Technologies: The integration of 3 key technologies distinguishes LLNL's electromechanical battery (EMB) from present-day flywheel systems. These technologies are: Electrostatic Generator/Motor (ESG): (very high efficiency with near-zero internal heat generation, utilizing an extremely simple and lightweight structure, eliminating point-loading stress-induced areas). Passive Magnet Bearings: (special permanent magnet arrays are used to levitate and to dynamically stabilize the rotating flywheel system, eliminating the need for complicated sensors and control circuits, which in turn, eliminates heat generation in the vacuum chamber and the corresponding active cooling system required). Carbon Fiber Composite Flywheel rotor employing special mechanical designs: (high-strength, low-density carbon composite material enables increased kinetic energy storage while achieving significant system weight savings). Additional attributes of LLNL's EMB include: - Projected 95% storage efficiency. - Simple and straightforward architecture promotes low cost, and high reliability. - Long "standby" energy storage lifetimes due to extremely low parasitic losses. - Long device lifetime as a consequence of 100% passive magnetic bearing design (no electromagnets), resulting in no frictional wearing of components and no heat-related issues. - No loss of capacity from number of charge-discharge cycles. - Near-zero internal heat losses from the electrostatic generator/motor and the passive magnetic bearing system, thus no requirement for an active cooling system.
Patent Abstract: 
The design calculations that have been performed in exploring the potentialities of LLNL's new approaches to flywheel energy storage have been built on existing and past LLNL flywheel programs, including a program aimed at flywheel systems for the bulk storage of electricity at utility scale. To achieve the requirements of such systems, as mentioned above, LLNL has developed some key new technologies, technologies that we believe are unique to flywheel energy storage.
Internal Laboratory Ref #: 
Lab Representatives
Share to Facebook Share to Twitter Share to Google Plus Share to Linkedin