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Distributed End-Use Thermal Energy Storage and the Smart Grid

Technologies to Reduce Peak Load and Maximize Use of Renewable Energy

Michael WinklerSchatz Energy Research Center

Copyright 2009, Schatz Energy Research Center, Arcata, CA

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Grid Limitations

20th Century Grid:Centralized, dispatchable generation

21st Century Requirements:Increasing demand for electricityDistributed generationIncreasing desire for intermittent rewewables

Results:Overloaded gridLimitations on intermittent renewables

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Fundamental Problem of Intermittent Renewables

Time mismatch of supply & demandPossible Solutions

Manage Renewable Sources Like Loads (@ < 20% penetration)ExportStore

treehugger.comhttp://plurionsystems.com/images/charts/Summer-peak-coincidence_pop.jpg

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Supply-Demand Mismatch

treehugger.comhttp://plurionsystems.com/images/charts/Summer-peak-coincidence_pop.jpg

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@ Source Other

Thermal

End-Use

Storage Types

Electrical

Cold

Refrig. Water

Heat

Space ProcessA/C

Plug-inHybrids

BatteryBanks

6Residential Energy Consumption Survey 2005, eia.doe.gov

Residential Energy Expenditures 2005

Space Heating

28%

Water Heating

15%

Refrigerators8%

Other Appliances

and Lighting34%

Air-Conditioning

15%

Total Thermal = 66%

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Battery vs. Thermal StorageCharacteristic Battery Storage Thermal StorageCost ($/kWh) $100-1000 $25-75

Cycle Life 300-500 Unlimited1st Law Efficiency 80-90% 75%-95%Energy Density

(Wh/L)100-250 Cooling

40 (water)260 (ice)Heating

40 (water)160 (hi-T, solid)170 (paraffin)

Preliminary Assessment of Battery Energy Storage and Fuel Cell Systems in Building Applications, Arthur D. Little, Inc., August 2, 2000engr.uconn.edu/~jmfent/ADL%20Building%20DOE%20report%20BES.pdf, P. 85, http://www.steffes.com/downloads/pdf/2100_tech_data_sheet.pdf

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Thermal Storage Media

ColdChilled WaterIce

Heat Hot WaterHigh-Temperature SolidsPhase-Change Media (PCM’s)

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Air Conditioners/Heat PumpsConvert electricity to heat/cold @high efficiency (COP Range: 2 to 5)

=Coefficient of Performance (COP) Electricity InHeat/Cold Out

Key enabling technologies to convert renewable energy (wind, solar-electric, etc.) into heat/cold

vortex.wcupa.edu/ec/graphics/geothermal.gif

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Reducing Peak Grid LoadPeak Shaving vs. Permanent Load Shifting

Peak ShavingShort-term comfort/service reductions to reduce peaks

Permanent load shiftingUsing storage to permanently shift load to far off-peakNo reductions in comfort or service

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8760 Hours of the Year

TDV

Wei

ghte

d En

ergy

Use

OFF

Pea

k

ON

Pea

k

Peak Shaving vs. Permanent Load Shifting (still using high-cost energy)

January June December

Significant On-Peak Cost

Demand ResponseA/C Cycling

TDV = time dependent value of energy; for additional information search: TDV cookbookIce Energy Corp.

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Permanent Load Shifting

8760 Hours of the Year

TDV

Wei

ghte

d En

ergy

Use

OFF

Pea

k

ON

Pea

k

January June December

Insignificant On-Peak Cost

Ice Energy Corp.

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Permanent Load ShiftingMove Building A/C energy to Far Off-Peak

created & stored

Low capacity factor High capacity factor

• Use what nature provides– Transmit energy when consumer demand is low– Store cooling energy at night when its cool

http://www.ctsavesenergy.org/files/ECMB%20Ice%20Energy%20Permanent%20Load%20Shifting%20r4.ppt.

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Permanent Load Shifting - Heat Storage

http://www.steffes.com/offpeak/thermelect/thermelect_overview.aspx

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Variable Renewable Energy…a Must Take Resource

Productively use itRamp another resource to balance systemCurtail itOr Store it for later use

Storage is the Storage is the ““Holy GrailHoly Grail”” for renewable for renewable energyenergy

steffes.com

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Renewables + Heat Pumps + TS =

+ +

Optimization of RenewablesEnergy ConservationEnergy EfficiencyLow Cost, Consumer Cooling & Heating

steffes.com

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Wind and Thermal Energy Storage

Create market for off-peak windReduce need to run on-peak generatorsIncrease availability of wind resource energyProvide bi-directional, utility-controlled regulation of energy resource

Ice Energy Corp.

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Wind Farm Output (2004)

http://www.wapa.gov/rm/PlanProjectsRM/docs/WACM_Wind.pdf

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WACM Load (2004)

http://www.wapa.gov/rm/PlanProjectsRM/docs/WACM_Wind.pdf

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Thermal Storage (TS) and Renewables

Wide use of Renewables requires storageStore renewable energy when available and provide backup using off-peak base load generationTS provides low cost, long life storage Use of renewables, heat pumps and TS significantly reduces carbon footprintLow Cost of operation for consumer

steffes.com

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TS and Renewables (continued)

Reduces our dependence on imported energy

Demand response benefits to Power Company

Optimizes use of available renewable power

Helps meet state RPS (Renewable Portfolio (Renewable Portfolio Standards)Standards)

steffes.com

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Evolution of Rates for Renewable Energy and Thermal Storage

1. Flat (kWh)2. Fixed Time-of-Use (kWh)3. Interruptible (kWh)4. Critical Peak Pricing (kWh)5. Real-Time (kWh)6. As-Available (kWh)7. Flat (delivered BTU’s)

A. Heat pumps/air conditioners owned by 3rd partyB. Charge for BTU’s, not kWh

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Advanced Rates, Smart Grid and Thermal Storage

Can enble users to:Use energy for compressors only when rates and grid load are lowestContinue full service during scheduled power interruptionsAccept excess energy from intermittent renewables as it is availableDo heating and cooling at low, predictable, fixed cost

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Thermal Storage and the Smart Grid

Smart Grid operator sends requests to demand-responsive loads when:

Grid load is lowIntermittent renewable energy supply > demand

Demand-responsive thermal storage loadsStore energy as heat/cold when grid operator requests, until storage is fullUse stored heat/cold as needed

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Putting it All TogetherSmart Grid/Demand-Responsive Loads

Ice Energy - How OSIsoft addresses our business requirements - Brian Parsonnethttp://www.osisoft.com/osisoft/downloads/Regional_Seminars/Denver/Ice%20Energy.ppt.

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Smart Grid - Evolution

gridpoint.com

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Conclusions

Two major challenges facing the Grid:Reducing peak loadsIncreasing the use of renewable energy

End-use Thermal Storage combined with Heat Pumps through a Smart Grid can play an important role in meeting both challenges

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Thermal Storage Manufacturers

Ice StorageBaltimore Air CoilCalmacDunham-BushIce EnergyIntegrated-Ice Systems Trinity Thermal Systems VogtIce

Heat StorageSteffesPower Tank (Germany)

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Cold Storage – PCM (ice)

Ice Energy Corporation

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Ice Energy Corporation

ice-energy.com/products/commercial/tabid/60/Default.aspx

Ice Bear 30 Hybrid Air Conditioner

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Calmac - Icebank

calmac.com/products/icebank.asp

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Heat Storage - PCM (paraffin)

http://www.powertank.de/fotos/presse/340-Zellen-Latentspeicher.JPG

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Heat Storage - PCM (paraffin)

http://www.powertank.de/engl/downloads/EN-1.pdf

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Heat Storage - PCM (paraffin)

http://www.powertank.de/engl/downloads/EN-1.pdf

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Heat Storage – Solid (magnetite ceramic)

http://www.steffes.com/downloads/pdf/TE-Article-1.pdf

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Heat Pump with Thermal Storage(TS)

http://www.steffes.com/offpeak/comfortplus/3100cutaway_large.aspx

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Smart Water Heater

Minimizes energy costs by coordinating the following with time-varying rates:

Time of water heatingElevation tank temperature

steffes.com

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Links

Ice StorageBaltimore Air Coil - baltimoreaircoil.comCalmac - calmac.comDunham-Bush - dunham-bush.com/pdf/DBush_ICE-CEL.pdfIce Energy - ice-energy.comIntegrated-Ice Systems - bio-radiant.com/PolarBearFR.htmlTrinity Thermal Systems - trinity-thermal.comVogtIce - tubeice.com/turbo/tes/tes.html

Heat StorageSteffes - steffes.com/offpeakPower Tank (Germany) - powertank.de/engl/willkommen.php