• Energy Research
• 7. Clean energy close
• 12. Responsible consumption close

This project’s mission was to achieve significant advances in the practical application of bulk high-temperature superconductor (HTS) materials to energy-storage systems. The ultimate product was planned as an operational prototype of a flywheel system on an HTS suspension. While the final prototype flywheel did not complete the final offsite demonstration phase of the program, invaluable lessons learned were captured on the laboratory demonstration units that will lead to the successful deployment of a future HTS-stabilized, composite-flywheel energy-storage system (FESS).

Research progress on the development of composite flywheels for use in a heat-engine/flywheel hybrid vehicle is reported. A design concept was generated for the instrumented containment assembly. Analytical results indicate that both the ''dead-weight-loaded bandwrap'' flywheel and the ''prestressed-rim bandwrap'' flywheel should significantly outperform Union Carbide Corporation-Nuclear Division's FY 1976/76T ''bandwrap composite'' flywheel. Analytical results to date indicate that the use of a hybrid rim with two or more materials of different elastic moduli, such as Kevlar-29/epoxy overwrapped with Kevlar-49/epoxy, should improve the flywheel performance. Additional transverse tensile characterization of Kevlar-49/epoxy, using three different room-temperature-curing epoxy resin formulations, resulted in no significant improvement over the approximately 1-ksi strength level previously attained in the FY 1976/76T flywheel.

A report is given summarizing Union Carbide Corporation-Nuclear Division's (UCC-ND's) composite flywheel program objectives and accomplishments for the period from May 1 through June 30, 1976. The necessity and urgency of national energy conservation is a well-recognized fact. Mechanical-energy storage, using rotating flywheels, is one of the few known methods for energy storage, and flywheels probably have the highest potential effectiveness for energy storage of any method now available. Initial application selected for the development of the composite flywheel is the heat engine/flywheel hybrid propulsion system for a vehicle, because of its high potential for the conservation of petroleum fuel in both the near and long-range time frames. Efforts have focused into key areas consistent with its experience base: state-of-the-art flywheel development, spin testing, and containment development. An operating performance goal of 20 watt-hr/lb (20 Wh/lb) energy density at an energy level of 0.56 kWh has been set by UCC-ND. The 20 Wh/lb goal encompasses both the composite flywheel and the hub that connects it to the shaft. It does not include the shaft. The goal exceeds the present performance of isotropic flywheels, and is also at the upper limit of current laboratory technology reported in the literature for compositemore » flywheels. The thick rim with radial overwrap bands was selected as the initial design concept. Kevlar-49/epoxy was selected as the construction material, and the end of the design phase is near. A process for fabricating full-scale Kevlar-49/epoxy thick rims was developed, and full-scale rims were successfully wound. More detailed information is presented on the development plan for this budgetary period, and the present accomplishments with respect to: (1) flywheel design, analysis, and fabrication and (2) spin testing are discussed.« less

The program to design, fabricate, and performance test a prototype, vehicular-sized, composite flywheel is described. The overall program scope encompasses development of both the flywheel and its containment; however, the FY 1976-1976T objective was directed toward development of the flywheel and testing it in existing facilities. The development effort was successful, leading to successful testing of a flywheel design which demonstrated an energy density performance of 10.1 Wh/lb during spin testing. The initial application selected for development of the composite flywheel was the heat engine/flywheel hybrid propulsion system for a vehicle. This application was selected by the ERDA Advanced Physical Methods Branch staff because of its high potential for conservation of petroleum fuel in both the near and far-term time frames. Other applications, such as utility load leveling, represent potential areas for significant energy savings but require more extensive development programs and funding resources. Successful development of a high-performance, composite, vehicular flywheel represents one step along the development path leading toward larger, higher-energy storage flywheel applications.

This report documents a high-level analysis of the benefit and cost for flywheel energy storage used to provide area regulation for the electricity supply and transmission system in California. Area regulation is an 'ancillary service' needed for a reliable and stable regional electricity grid. The analysis was based on results from a demonstration, in California, of flywheel energy storage developed by Beacon Power Corporation (the system's manufacturer). Demonstrated was flywheel storage systems ability to provide 'rapid-response' regulation. Flywheel storage output can be varied much more rapidly than the output from conventional regulation sources, making flywheels more attractive than conventional regulation resources. The performance of the flywheel storage system demonstrated was generally consistent with requirements for a possible new class of regulation resources - 'rapid-response' energy-storage-based regulation - in California. In short, it was demonstrated that Beacon Power Corporation's flywheel system follows a rapidly changing control signal (the ACE, which changes every four seconds). Based on the results and on expected plant cost and performance, the Beacon Power flywheel storage system has a good chance of being a financially viable regulation resource. Results indicate a benefit/cost ratio of 1.5 to 1.8 using what may be somewhat conservative assumptions. A benefit/cost ratiomore » of one indicates that, based on the financial assumptions used, the investment's financial returns just meet the investors target.« less

New materials and energy problems are increasing the feasibility of using flywheel energy storage systems to power personal automobiles. A promising concept appears to be the combination of the high specific power density of a flywheel with the high specific energy density of a small heat engine. A technical and fuel economy assessment of a small personal vehicle powered by a hybrid flywheel/heat engine drive system is presented. Technical evaluations indicate that a flywheel/heat engine system based on improved materials technology could serve as a practical vehicle drive. While somewhat limited in performance, the proposed system could produce significant improvements in fuel consumption rates. Technological advancements in materials and power transmission systems would make flywheel/heat engine systems even more attractive.

An assessment has been conducted for the DOE Vehicle Technologies Program to determine the state of the art of advanced flywheel high power energy storage systems to meet hybrid vehicle needs for high power energy storage and energy/power management. Flywheel systems can be implemented with either an electrical or a mechanical powertrain. The assessment elaborates upon flywheel rotor design issues of stress, materials and aspect ratio. Twelve organizations that produce flywheel systems submitted specifications for flywheel energy storage systems to meet minimum energy and power requirements for both light-duty and heavy-duty hybrid applications of interest to DOE. The most extensive experience operating flywheel high power energy storage systems in heavy-duty and light-duty hybrid vehicles is in Europe. Recent advances in Europe in a number of vehicle racing venues and also in road car advanced evaluations are discussed. As a frame of reference, nominal weight and specific power for non-energy storage components of Toyota hybrid electric vehicles are summarized. The most effective utilization of flywheels is in providing high power while providing just enough energy storage to accomplish the power assist mission effectively. Flywheels are shown to meet or exceed the USABC power related goals (discharge power, regenerative power, specific power,more » power density, weight and volume) for HEV and EV batteries and ultracapacitors. The greatest technical challenge facing the developer of vehicular flywheel systems remains the issue of safety and containment. Flywheel safety issues must be addressed during the design and testing phases to ensure that production flywheel systems can be operated with adequately low risk.« less

A report is given of the results accomplished during the third year of a three-year research program, the overall goal of which has been to conceive and evaluate practical ways to increase automobile fuel economy by energy management within the engine-transmission-vehicle system. The third year was devoted primarily to the detailed design, construction, and preliminary evaluation of a Flywheel Energy Management Powerplant (FEMP) installed in a Pinto. The vehicle has been built to experimentally verify performance simulations and to allow the practical aspects of a real flywheel vehicle to be studied. The FEMP consists basically of an internal combustion engine, a high-speed energy-storage flywheel, and a hydrostatic power-split continuously-variable transmission (CVT) system. The flywheel drives the car, and the engine comes on to ''recharge'' it (with efficient wide-open throttle operation) only when the flywheel speed drops below a predetermined value. The concept also permits effective and efficient regenerative braking. Computer simulations have indicated an improvement in city fuel mileage of about 50%, with improvements of 100% appearing feasible with further research. Preliminary testing of the car shows favorable performance.

Finding efficient and satisfactory energy storage systems (ESSs) is one of the main concerns in the industry. Flywheel energy storage system (FESS) is one of the most satisfactory energy storage which has lots of advantages such as high efficiency, long lifetime, scalability, high power density, fast dynamic, deep charging, and discharging capability. The above features are necessary for electric vehicles (EVs), railways, renewable energy systems, and microgrids. Also, electrical machines, power electronics converters, and control systems are the cores of energy transfer in FESS. Therefore, they have a critical role in determining efficiency, power rating, power factor, cost, angular velocity, and volume of FESS. So, in this study, the FESS configuration, including the flywheel (rotor), electrical machine, power electronics converter, control system, and bearing are reviewed, individually and comprehensively. Additionally, the mentioned components have been categorized to be a guide for future research. The investigated electrical machines are compared by Finite Element Analysis (FEA). Subsequently, our laboratory’s measurement results are reviewed experimentally showing the progress in the field of FESS, such as designing robust control algorithms and an Interior Permanent Magnet-Synchronous Reluctance Machine (IPM-SynRM) to use in FESS.