Electrical/Thermal Conversion and Storage Technology and Opportunities Mike He, Achintya Madduri, Evan Reutzel, Seth Sanders

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Electrical/Thermal Conversion and Storage
Technology and OpportunitiesMike He, Achintya
Madduri, Evan Reutzel, Seth Sanders

• Energy Storage Overview and Intro to Flywheel
  Energy Storage
• Solar-Thermal, Thermal Storage, CHP Mike and
  Achintya
• Flexible ac/dc line interface Evan

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Energy Storage Overview

• Energy arbitrage return
• 0.30/kw-hr-day gives about 100/kw-hr-year
• For 3 year ROI capital value at 300/kw-hr
• Extra value in
• Avoided demand charge on customer side
• UPS, islanding function
• Power quality

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Electricity Storage Assoc Chart
http//www.electricitystorage.org/site/technologie
s/
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Per cycle capital cost (ESA)
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DOE National Energy Technical Laboratory Report,
Sept 2009
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History Integrated Flywheel Energy Storage
System

• 150 w-hr system scaled for HEV application in
  late 1990s
• Homopolar Synchronous Design
• Single-Piece Solid Steel Rotor/Energy Accumulator
• 3-5 W-hr/kg energy density for complete system
• Six-Step Drive for total system eff. 85
• Tested to 60 krpm, rated to 100 krpm

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Flywheel Energy Storage

• New effort with Prof. Hari Dharan (ME Dept)
• Infinite cyclability
• Power and energy scale independently
• Can use commodity materials
• Steel, composites, natural fiber composites
• Technical challenges, details in
• rotor materials, design
• containment
• Motor/alternator
• bearing system(s)
• power electronic interface and controls

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Estimated cost breakdown, based on 40-100 kw-hr
system (/kWh)
Rotor/vacuum housing/containment 150
Bearings 50
Motor/generator 10
Power electronics 10

TOTAL 220
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Rotor Analysis

• Energy density strength/weight ratio
• Exs
• High strength steel 66 W-hr/kg
• Engineering composites much higher 500 Whr/kg
• Derate by
• Shape factor 0.5 -1
• Speed range 0.84 for 40-100 range
• Safety/fatigue factor
• Steel example 15-30 W-hr/kg after derating
• Fabricated steel cost 2-4/kg gt 60-120/kw-hr
• Design for no failure, like aircraft