Borehole Thermal Energy Storage (BTES)

Transcription

Session 6: HVAC Technologies -BTESBorehole Thermal Energy Storage (BTES)Chuck Hammock, PE, LEED AP BD C, CGDAndrews, Hammock & Powell-Consulting Engineers10 August 2016, 1400-1530Rhode Island Convention Center Providence, Rhode Island

Presentation Outline and Objectives Provide a brief overview of multiple forms ofUnderground Thermal Energy Storage (UTES & TES)e.g. Borehole Thermal Energy Storage (BTES) orAquifer Thermal Energy Storage (ATES) Advise what applications are UTES appropriate Learn what differentiates UTES/BTES from “normal”GroundLoop Heat Exchangers (GHX) andGeothermal Heat Pump (GHP) “architectures” Present the initial results of ESTCP’s EW-201135 Overwhelm you with acronyms2Energy Exchange: Federal Sustainability for the Next Decade

Brief Overview of TES/UTES Thermal Energy Storage (TES) can be:– Above ground, below ground or both– Sensible only, latent only or both– Diurnal, Seasonal or Both In the Underground form, UTES is:– Normally ATES or BTES but can be.– Hybrid UTES: Combine above groundand underground Storage (Drakes Landing)– Pit Storage:45 Contributors, One American(200,000 M3, 85 C, Denmark) for heat ora cold version called SeasonalSnow Storage (SSS)SSS- Sundvall Sweden Storage– Abandoned Mines or Flooded natural caverns (CTES)– Energy Piles (basically a multi-purpose structural pile/BTES system)3Energy Exchange: Federal Sustainability for the Next Decade

ATES and Hybrid BTES ATES (similar to “American”open loop Geo systems butbetter). In use around theworld, but currently justone “cold-only” ATES systemin the USESTCP ATES-Ft. Benning, GA Hybrid BTES (warm storage)at Drakes Landing nearCalgary, CanadaDrakes Landing, Canada4Energy Exchange: Federal Sustainability for the Next Decade

BTES for non-GHP applicationsSolar Thermal Application-Drakes Landing, Canada“Hybrid” with above ground thermal storage & BTESCombined Heat & Power (CHP) plant with BTES5Energy Exchange: Federal Sustainability for the Next Decade

BTES Concepts Technology is well suited to “Geothermal HeatPumps” (GHP) but is equally appropriate with SolarThermal (Drakes Landing), any waste heat (e.g. CHP,Industrial processes) or “waste cool” situation Differentiated from “American” closed loop GHXarchitectures due to engineered thermal storage &:– Reversing valves allowing water to flow in or out of core– Boreholes piped in series (versus all in parallel) thatallow varying Delta T across each borehole– Concentric (solid & hollow) cylindrical thermal zones– Actively managed heat/cold “hybrid” component6Energy Exchange: Federal Sustainability for the Next Decade

Germany’s VDI-4640 Underground ThermalEnergy Storage (UTES) GuidelinesEnergy Exchange: Federal Sustainability for the Next Decade

When to consider BTES? Above 50 Tons? There probably is a min.size threshold before BTES should beconsidered, due to reversing valve, etc. cost,but theoretically, three thermal zones can be created with asfew as 30 boreholes, therefore 30-60 tons (typ.) Smallest/Largest by AH&P so far: 60/336 boreholes If smaller GHX footprint needed (due to closer boreholespacing since engineered for thermal storage not just heatextraction/dissipation). Ideally square/circular land availability,but the “cylinder” can be oval (VA’s BTES-5) Anytime you are considering GHPs and/or have a good sourceof “free” heat or cold (CHPs, Solar, etc.) Water conservation desired while retaining high EERs All Fed. Properties. BTES (unlike ATES) is a 50 state technology8Energy Exchange: Federal Sustainability for the Next Decade

BTES-1 (ESTCP/NAVFAC), Marine Base (MCLB)Albany, GeorgiaBTESReversingValves &AdiabaticDry-CoolerCircular HDPE Headers/Radial Sub-Mains at BTES-19Heat-Recovery Water-to-Water GHPEnergy Exchange: Federal Sustainability for the Next Decade

BTES-2/3/4 (NAVFAC); BTES-5 (VA)66 Ton BTESBTES-2 MCLB Albany GA183 Ton BTESBTES-3 MCLB Albany GA56 Ton BTESBTES-4 MCLB Albany GA“Oval” BTES-5BTES-5 VA Perry Point, MD10Energy Exchange: Federal Sustainability for the Next Decade

BTES-1 has a 2.6 km fiber optic based Distributed TemperatureSensing (DTS) system with 1300 underground temperature pointsRack Mounted DTS ComputerDTS Distance/Sampling TemperatureAccuracy Table4” dia./225’ long DTS Well(Typ. for 9)BTES-1 Temperature ReadingsEnergy Exchange: Federal Sustainability for the Next Decade

BTES-1 with true Energy-Water-Nexus controlCombining BTES with Adiabatic Dry-Coolers provides a virtualEnergy-Water-Nexus “slider bar” to reduce/eliminate thecopious water consumption generally associated with traditionalcooling towers while still exceeding water-cooled EERsModerate Water/Lowest KWH-KWDNo Water/Moderate KWH-KWDAdiabatic 100BTES Max1616BTES Winter200-1600BTES Yr. Ave200-400Annual Water ReductionVirtual Energy-Water BTES80-100%Nexus Slider-BarClose-up of hydrophilic evaporative coolingpad/gutter at adiabatic dry-cooler coil inletEnergy Exchange: Federal Sustainability for the Next Decade

Temperature Plots of BTES Entering and Leaving Water &Charging/Discharging Modes In the next few slides, the blue line represents:– The water at the perimeter of the BTES– If the system is being “charged with cold”, this is the temperatureleaving the outer boreholes. If the system is “discharging its cold”, thisrepresents the warmer water entering at the outer borehole Conversely, the green line represents the water at the core of theBTES that is entering the core during “charging” and leaving thecore during “discharging”Red shading represents “cold discharging”or heat going into the BTES (typical)Sample plot of water temperatures during cold discharging-only mode in early fallEnergy Exchange: Federal Sustainability for the Next Decade

Temperature Plots of BTES Entering and LeavingWater & Charging/Discharging Modes (continued)Sample plot of water temperatures during DIURNAL STORAGE times inlate fall (“cold-discharging” during the day & “cold-charging” at night)Blue shading represents “charging”, (cold storage) orheat being removed from the BTES (typical)Sample plot of water temperatures during continuous (24 hr/day) “coldcharging” SEASONAL STORAGE mode in winterEnergy Exchange: Federal Sustainability for the Next Decade

Temperature Plots of Inner, Middle and OuterBorehole Delta T’sSample plot of water temperatures differentials across three boreholes in seriescharging the BTES in late fall with “cold”. The teal line is the delta T across theinner borehole, the green the middle borehole and the blue the outerborehole. The most heat transfer is occurring exactly where it is needed .at the core of the BTESEnergy Exchange: Federal Sustainability for the Next Decade

ESTCP’s EW-201135 (BTES-1) 11 monthresults MCLB Albany ( as of 30 June 2016) KBTUs/Ft2 are down 48.1% even when this highly coolingdominate building experienced a 14% increase in Cool. Deg.Days (CDD) and room temps kept 1 F colder. Combinedannual elec., gas, water & maint. savings are 169k/year On-site gas consumption &emissions eliminated. So far, evaporative water consumption is zero a reduction of5.1M gallons/yr., though we may chose to consume up to 1Mgallons (20% of baseline per the ESTCP Demo Plan) to lowerKWH/KWD further Current payback on 1.8M BTES cost is 10.7 years “Technology Transfer”: A with 4 moreBTES system currently under design andscheduled to bid in late 201616Energy Exchange: Federal Sustainability for the Next Decade

Session 6: HVAC Technologies -BTESQuestions and AnswersChuck Hammock, PE, LEED AP BD C, CGDAndrews, Hammock & Powell, Inc.Consulting Engineers250 Charter LaneMacon, GA 31210chammock@ahpengr.com478-405-8301, Ext. 6362Skype: chuck.hammock.ahp17Energy Exchange: Federal Sustainability for the Next Decade

Borehole Thermal Energy Storage (BTES) Session 6: HVAC Technologies -BTES Chuck Hammock, PE, LEED AP BD C, CGD Andrews, Hammock & Powell-Consulting Engineers 10 August 2016, 1400-1530 . Energy Exchange: Federal Sustainability for the Next Decade Presentation Outline and Objectives