Chilled Water Thermal Energy Storage –– an Alternative to ...

1 FEFPA Summer 2015 Chilled Water Thermal Energy StorageChilled Water Thermal Energy Storage an Alternative to static Icean Alternative to static IceChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Presentation By:Presentation By:Marc Rouleau, PEMarc Rouleau, PEExecutive Director of Facilities Management,District School Board of Collier CountyAdrian Roman, RA, AIAA drian Roman, RA, AIAD istrict Architect / Facilities Planning and Design,District School Board of Collier CountyLawrin T. Ellis, PE, LEED AP,Lawrin T. Ellis, PE, LEED AP, CxACxAPrincipal / Senior Mechanical Engineer,TLC Engineering for ArchitectureChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Presentation OutlinePresentation Outline Introduction to Thermal EnergyStorage (TES) Basic Design of Chilled WaterStorage Systems Tank Location Construction of Chilled WaterStorage Tank Operation of Chilled Water StorageSystems Economic Comparison of ChilledWater vs.

2 static IceChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Introduction to Thermal Energy StorageIntroduction to Thermal Energy StorageThermal Energy Storage (TES) Basic Concept TES Systems remove heat from or add heat to astorage medium for use at another time Most Common Application is Comfort Cooling Energy is Charged, Stored, and Discharged - Can be Daily, Weekly,or Seasonally Storage unit is Ton-hour Means to Reduce Total Utility Bill and/or Size of EquipmentApplications that Benefit from TES Loads are Cyclical Energy Costs are Time-Dependent (Time-of-Use Rate)

3 Utility Rebates or Economic Incentives for Load-Shifting EquipmentFocus on static Ice and Chilled Water StorageChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Introduction to Thermal Energy StorageIntroduction to Thermal Energy StorageThermal Energy Storage (TES) - static Ice Typical Storage Medium Water , due to High Latent heat Capacityof 144 Btu/lb Latent Technology achieves capacity through change of state fromSolid to Liquid during Melt process Typically Requires about ft3ice per ton-hour of cooling Example 5,000 ton-hours Cooling requires 7,275 ft3ice (roughly54,420 gallons/ Water ) Chilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Introduction to Thermal Energy StorageIntroduction to Thermal Energy StorageThermal Energy Storage (TES)

4 - Chilled Water Typical Storage Medium Water , specific heat of 1 Btu/lb F Sensible Technology achieves capacity through high specific heat ofwater Requires about ft3water per ton-hour (at 20 Degrees Delta T) Example 5,000 ton-hours Cooling requires 53,300 ft3water (roughly398,725 gallons/ Water ) Chilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsTypes of Chilled Water Storage Systems Simplest Form Series Storage Tank Effective at reducing on-peak electric demand Drawbacks Tendency for stagnation, Higher leaving watertemperaturesChilled Water TES an Alternative to static IceRouleau, Roman.

5 Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsTypes of Chilled Water Storage Systems Multiple Tanks Parallel Storage Tanks Minimizes stagnation associated with Series Tank Drawbacks Need accurate means of measuring tank volume,Complex Controls to ensure proper sequencingChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsTypes of Chilled Water Storage Systems Most Common Stratified Storage Tanks, System Preferredby Collier County Schools Exploits tendency of warm and cold Water to stratify Drawbacks Requires specifically engineered diffusersdesigned to promote stratificationChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsStratified Storage Tanks - Understanding Thermocline Naturally occurring change in density of Water between 44-54degrees.

6 Thermal layer separating warmer Water at top from coolerwater at bottom. Design of Stratification Diffusers optimized to maintain Thermocline . Chilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsStratified Storage Tanks Tank Sizing Estimates Building/Campus Load Profile Summer Peak Full Storage Shift TES Covers Load (Typical Operation) Total Capacity based on Ton-Hours ShiftedChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsStratified Storage Tanks Tank Sizing Estimates Building/Campus Load Profile Summer Peak Part Storage Shift TES Covers Peak Loads, AlternateApproach to Full ShiftChilled Water TES an Alternative to static IceRouleau, Roman.

7 Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsStratified Storage Tanks Tank Sizing Estimates Florida Power and Light Time of Use Tariff Summer and Winter PeakPeriods TES Operates During On-Peak Periods to MinimizeEnergy CostsChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsStratified Storage Tanks Tank Sizing Estimates Tank Storage Volume Calculation using Figure of Merit FOM of Sizing Estimates is approximately (90%) Given FOM, Total Ton-Hrs and Tank Differential Temperature,solve of Volume Using:Note.

8 Specific Gravity of Water at 50 F is approximately Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Design of Chilled Water Storage SystemsDesign of Chilled Water Storage SystemsStratified Storage Tanks Estimating Tank Geometry Tall, Slender Tanks are Preferred to Optimize Thermocline andMinimize Footprint Where practical, Tank Height should be greater than highestair vent in Chilled Water Lines Prevents Drainback Quick Formula for Tank Sizing:Volume, gallons = = Inside Tank Diameter, FeetH = Height of Water , FeetAssuming 750,000 gallons (6,583 Ton-hrs at 14 Degree Delta T)

9 AndDiameter of 50 feet, Height of Water is approximately Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank LocationAfter tank sizing estimates - but prior to construction -determine tank locationLocation can have a profound impact on cost, campusappearance and your relationship with the communityDetermining location is a balancing act school needs,cost, community concernsChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank LocationFirst Review Local Ordinances Height restrictions Aesthetic limitations Prohibited structures Florida Statutes (1)(a) and Florida Building Code District from compliance with local OrdinancesChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank Determine optimal location(s)

10 Distance from chiller plant and buildings Tank can act as chiller plant sound block Shield tank with buildings May be limited by retention areas, sporting fields, easements, terrainfeatures, buried Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank Location Conduct Internal Review Generate renderings All proposed locations Highlight potential visual impacts Illustrate plan to eliminate or minimize visual impacts Review locations with Principal and other stakeholders (maintenance,facility ) Chilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank LocationRenderings may look like this view from Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank LocationWith ground level Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank LocationChilled Water TES an Alternative to static IceRouleau, Roman, Ellis 7 July 2015 Tank LocationTank LocationChilled Water TES an Alternative to static IceRouleau, Roman.