Flywheel Energy Storage for a
Smart Distribution Grid
Eric Severson,
Advisor: Ned Mohan
Department of Electrical and Computer Engineering
University of Minnesota
200 Union Street
Minneapolis, MN 55455
July 15, 2015
Eric Severson, Ned Mohan
Flywheel Energy Storage Research
1
Conventional flywheel system
Bearing system
PM Motor
Containment and
vacuum housing
10 kRPM - 100 kRPM
Magnetic levitation
Composite flywheel
Bearing system
Traditional Flywheel Design
Eric Severson, Ned Mohan
Flywheel Energy Storage Research
2
Conventional Flywheel Technology
High power to energy stored ratio
Very fast response time
Typical applications:
-
Pulsed-power
Power quality and UPS
Frequency regulation
More-electric vehicles
Often compete with super
capacitors
Best designs completely
self-discharge in 24 hours
Eric Severson, Ned Mohan
Companies:
Beacon Power LLC
PowerTHRU
Active Power, Inc.
VYCON, Inc.
Rotonix USA, Inc.
Amber Kinetics, Inc.
Velkess Inc.
Flywheel Energy Storage Research
3
Research Focus
Goal: Simultaneously provide regulation and load-following
services while being located on the distribution grid
Issues to address for use as load-following energy storage
Self-discharge
Cost / kWh
Energy Density
Eric Severson, Ned Mohan
Flywheel Energy Storage Research
4
Proposed flywheel module design
Flywheel
Bearing system
Rotor
Stator
PM Motor
Containment and
vacuum housing
Backup bearing
system
Composite flywheel
Bearingless ac
homopolar motor
Containment and
vacuum housing
Composite flywheel
Bearing system
Passive axial
magnetic bearing
Traditional Flywheel Design
Eric Severson, Ned Mohan
Proposed Flywheel Design
Flywheel Energy Storage Research
5
Hardware prototypes
Eric Severson, Ned Mohan
Flywheel Energy Storage Research
6