Rotating machines as an alternative method of energy storage and power management mike werst - feb 2010
- 1. Rotating Machines as Energy Storage and Power Management SystemsMike Werstm.werst@cem.utexas.eduFebruary 10, 2010
- 2. TopicsAbout UT-Center for ElectromechanicsFlywheels as energy storageKinetic energy storageComparison to other forms of energy storagePeak power vs. peak energyFlywheel topologiesFlywheel Energy Storage Examples
- 3. Areas of TechnologyVG 12983aBiotechElectric Power• Electromechanical cell manipulation• Advanced Generators• Electric Grid Control• Energy Storage• Distributed Generation TechnologyDefense• Missile and Aircraft Launcher• All Electric Ship• Advanced Wheeled and Tracked Vehicles• Electromagnetic Guns• Electromagnetic ArmorSpace• Space Power• Electromagnetic Launch• Satellite Attitude ControlTransportation• Advanced Trains• Hybrid Vehicles• Active Suspension for Vehicles• Wheel Motors• Intelligent HighwaysOil & Gas• Exploration• Transmission
- 4. Flywheel Energy StorageWikipedia definition: “A flywheel is a mechanical device with a significant moment of inertia used as a storage device for rotational energy.”*Holm et. al., “A Comparison of Energy Storage Technologies as Energy Buffer in Renewable Energy Sources with respect to Power Capability.”Flywheels have a much broader range of usage than given credit for.
- 5. Kinetic EnergySpecific Strength of Selected Materials*Burr, “Mechanical Analysis and Design, 1981Flywheel energy storage efficiency is dependent on material and mass distribution
- 6. Flywheel HighlightsVG 12973eBackup Bearings• Conducted flywheel tests, including– Flywheel only tests to identify failure modes and structural margins– Flywheel burst tests to test candidate containment designs• Demonstrated life of more than 110,000 cycles with a 50% DODMagneticBearingsMotor GeneratorGimbal ShaftComposite FlywheelContainment System
- 7. Flywheel ChallengesLossesVacuum air gap significantly reduces windage losses at the price of vacuum pump auxiliaryBearingsRoller bearing require lubricationMagnetic bearings expensive and require touch-down bearingsSuperconducting bearings need developmentCarbon fiber material and manufacturing costDemand for high modulus/high strength carbon fiberIndustrial participation/competitiveness will bring mfg cost downFlywheel safetyDesign marginFlywheel health monitors/fault protectionContainment
- 8. VG 12973aKinetic Energy StorageApplication dictates flywheel topology that meets energy and power requirementsPartially-Integrated TopologyNon-Integrated TopologyFully-Integrated Topology
- 9. Flywheel Spin TestsVG 12973f• Flywheel tests to-date:– Numerous burst tests (modified design for containment proof tests)– Loss of vacuum test– Over-speed “As Built” Test- Preload loss- 1120 m/s- Benign and recoverable– Coupon/Fatigue testsMulti-ring preloaded flywheelHydroburst test couponHigh temperature & pressure autoclave4-axis filament winder
- 10. Technical Successes - Flywheel VG 12973g• Record tip speed for composite flywheel/arbor assembly (1.34 km/s)• Key features– Composite structural arbor design– Detailed material andmanufacturing process QA
- 11. CEM Flywheel ComparisonDesignedDesignedBuilt & testedBuilt & tested
- 12. Flywheel Energy Storage System for the International Space Station (FESS)• Operations advantages– Higher round trip efficiency– Known state-of-charge– Offer more flexibility in charge/discharge profiles– Doubled contingency power (energy)• Significant life cycle cost savings– Reduced logistics (up-mass & down-mass)– Reduced maintenance (EVA- IVA Hr/Yr) FW Battery (+ Electronics) (+ Electronics)Nominal Power 4.1 kW 4.1 kW Peak Power 6.6 kW 6.6 kWEnergy Delivered 5.6 kW-hr 4.6 kW-hrContingency Power 2 orbits 1 orbitLife Expectancy >15 years 5-6 years
- 13. Advanced Locomotive Propulsion (ALPS) Program FlywheelVG 12973h• electrical load leveling for hybrid electric locomotive • flywheel stores 480 MJ• @ 15,000 rpm• 2 MW motor/generator – ~3 min discharge• Testing with high input and output power
- 14. Backup BearingsRadial BearingStator WindingPermanent Magnet RotorComposite FlywheelMaterialsAluminumCeramicPermanent MagnetWindingsTitaniumInconelCompositeStainless SteelSteelCombo BearingTransit Bus FlywheelEnergy Storage:Power:2 kWhr stored, 1 kWhr delivered150 kW peak, 110 kW cont.,Between 30,000 and 40,000 RPMComposite tip speed:Application:930 m/s at 40,000 rpmPower averaging for 15 tonHybrid Electric Bus
- 15. CEM Flywheel Energy Storage Systems for Military ApplicationsVG 11536.pptS 4101.0607Composite Rotor Pulse Alternator664 MW, 2.5 kW-h(1991)Iron Core Pulse Alternator800 MW, 10.5 kW-h(1987)Composite Rotor Pulse Alternator2.4 GW, 11 kW-h(1995) ?S 3010.1993S 3910.1748Composite Rotor & Stator Pulse Alternator3 GW, 6.4 kW-h(1997)Current EM Gun Power SupplyResearch is Ongoing at CEM(2009)Electromagnetic Aircraft Launch System (EMALS) Energy Storage System(2006)
- 16. Homopolar Generator (HPG) FlywheelsFaraday disks1/10s to 10s of second discharge ratesVery high current/low voltage machinesCEM HPGs used for variety of applicationsLarge x-section resistive welding—12” sch. 60 pipe weldsRailguns—90mm, 9MJ muzzle energy High-field, single-turn magnets—9MA, 20T toroidal magnet All Iron Rotating (AIR) HPG6.2 MJ, 50 V, 750 kA60 MJ HPG Set—6 ea, 100V, 1.5MA/gen
- 17. Flywheel vs. Electrochemical Energy Storage 13121125101736948100,0001,000,000
- 18. SummaryAdvanced carbon materials and manufacturing methods enableEnergy densities comparable to chemical storage devicesExtremely high power densities for pulsed power applicationsFlywheels capable of wide range of energy storage applications: .01s to 1800sMany challenges have been overcome: additional R&D could improve energy storage capacity, efficiency and usage