Conceptual design of a flywheel energy storage system. Final report

Technical Report · Thu Nov 01 04:00:00 EST 1979

OSTI ID:5566040

A conceptual design of a flywheel energy storage system suitable for on-site interfacing with residential photovoltaic (PV) energy sources is developed. The basic design objective provides a generous margin of safety and above-average reliability and efficiency at the lowest practical cost. The basic design concept and the general approach to the conceptual design of the energy-storage system are described. The basic concept to interface with PV energy sources utilizes a constant voltage motor/generator directly coupled to a flywheel rotor. The voltage level of the motor is maintained at the optimum operating voltage of the array of PV cells and permits peak-power tracking. Power is withdrawn from the flywheel-driven generator when the voltage output of the array drops below its optimum value, and power is delivered to the flywheel via the generator (then operating as a motor) when the voltage rises above the optimum value. A variety of motor types and flywheel-rotor types has been studied to arrive at a conceptual design to meet the program objectives. A fiber-composite rotor driving a separately-excited motor satisfies the basic requirements. To obtain acceptable efficiency and low run-down losses, the flywheel operates in a vacuum and has a combination of magnetic-thrust support and ball bearings to reduce bearing friction in an economical fashion. The need for rotary vacuum seal is eliminated by the use of a hermetically-sealed magnetic power coupling. Cost of the system has been determined for production models to be produced in annual quantities up to one-hundred thousand for both 10-kWh and 50-kWh capacities, and also for a 10 kWh one-of-a-kind demonstration model.

• Research Organization: Brobeck (William M.) and Associates, Berkeley, CA (USA)
• DOE Contract Number: EY-76-C-04-0789
• OSTI ID: 5566040
• Report Number(s): SAND-79-7088
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140600 -- Solar Energy-- Photovoltaic Power Systems
25 ENERGY STORAGE
250500* -- Energy Storage-- Flywheels
29 ENERGY PLANNING, POLICY, AND ECONOMY
290700 -- Energy Planning & Policy-- Transport & Storage
CAPACITY
COST
DATA
DATA FORMS
EFFICIENCY
ENERGY LOSSES
ENERGY STORAGE
ENERGY STORAGE SYSTEMS
EQUIPMENT INTERFACES
EVALUATED DATA
EVALUATION
FLYWHEEL ENERGY STORAGE
INFORMATION
INSOLATION
LOSSES
NUMERICAL DATA
PEAK LOAD
PHOTOVOLTAIC POWER PLANTS
PLANNING
POWER LOSSES
POWER PLANTS
RESIDENTIAL SECTOR
ROTORS
SIMULATION
SOLAR POWER PLANTS
SPECIFICATIONS
STORAGE
TABLES