borehole thermal energy storage (btes) · 2016-08-18 · borehole thermal energy storage (btes)...
TRANSCRIPT
Rhode Island Convention Center • Providence, Rhode Island
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
• Provide a brief overview of multiple forms of Underground Thermal Energy Storage (UTES & TES) e.g. Borehole Thermal Energy Storage (BTES) or Aquifer Thermal Energy Storage (ATES)
• Advise what applications are UTES appropriate
• Learn what differentiates UTES/BTES from “normal” GroundLoop Heat Exchangers (GHX) and Geothermal Heat Pump (GHP) “architectures”
• Present the initial results of ESTCP’s EW-201135
• Overwhelm you with acronyms
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Energy Exchange: Federal Sustainability for the Next Decade
• 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 ground
and underground Storage (Drakes Landing)
– Pit Storage: (200,000 M3, 85°C, Denmark) for heat or a cold version called Seasonal Snow Storage (SSS)
– Abandoned Mines or Flooded natural caverns (CTES) – Energy Piles (basically a multi-purpose structural pile/BTES system)
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Brief Overview of TES/UTES
45 Contributors, One American
SSS- Sundvall Sweden Storage
Energy Exchange: Federal Sustainability for the Next Decade
• ATES (similar to “American” open loop Geo systems but better). In use around the world, but currently just one “cold-only” ATES system in the US
• Hybrid BTES (warm storage) at Drakes Landing near Calgary, Canada
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ATES and Hybrid BTES
Drakes Landing, Canada
ESTCP ATES-Ft. Benning, GA
Energy Exchange: Federal Sustainability for the Next Decade 5
BTES for non-GHP applications
Solar Thermal Application-Drakes Landing, Canada “Hybrid” with above ground thermal storage & BTES
Combined Heat & Power (CHP) plant with BTES
Energy Exchange: Federal Sustainability for the Next Decade
• Technology is well suited to “Geothermal Heat Pumps” (GHP) but is equally appropriate with Solar Thermal (Drakes Landing), any waste heat (e.g. CHP, Industrial processes) or “waste cool” situation
• Differentiated from “American” closed loop GHX architectures due to engineered thermal storage &:
– Reversing valves allowing water to flow in or out of core
– Boreholes piped in series (versus all in parallel) that allow varying Delta T across each borehole
– Concentric (solid & hollow) cylindrical thermal zones
– Actively managed heat/cold “hybrid” component 6
BTES Concepts
Energy Exchange: Federal Sustainability for the Next Decade
Germany’s VDI-4640 Underground Thermal
Energy Storage (UTES) Guidelines
Energy Exchange: Federal Sustainability for the Next Decade
• Above 50 Tons? There probably is a min. size threshold before BTES should be considered, due to reversing valve, etc. cost, but theoretically, three thermal zones can be created with as few 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 borehole
spacing since engineered for thermal storage not just heat extraction/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 source of “free” heat or cold (CHPs, Solar, etc.)
• Water conservation desired while retaining high EERs • All Fed. Properties. BTES (unlike ATES) is a 50 state technology
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When to consider BTES?
Energy Exchange: Federal Sustainability for the Next Decade 9
BTES-1 (ESTCP/NAVFAC), Marine Base (MCLB) Albany, Georgia
BTES
Circular HDPE Headers/Radial Sub-Mains at BTES-1 Heat-Recovery Water-to-Water GHP
Reversing Valves & Adiabatic
Dry-Cooler
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BTES-2/3/4 (NAVFAC); BTES-5 (VA)
BTES-5 VA Perry Point, MD
66 Ton BTES 183 Ton BTES
56 Ton BTES
BTES-4 MCLB Albany GA
BTES-3 MCLB Albany GA BTES-2 MCLB Albany GA
“Oval” BTES-5
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BTES-1 has a 2.6 km fiber optic based Distributed Temperature
Sensing (DTS) system with 1300 underground temperature points
Rack Mounted DTS Computer
4” dia./225’ long DTS Well (Typ. for 9)
DTS Distance/Sampling Temperature Accuracy Table
BTES-1 Temperature Readings
Energy Exchange: Federal Sustainability for the Next Decade 12
BTES-1 with true Energy-Water-Nexus control
Moderate Water/ Lowest KWH-KWD
No Water/ Moderate KWH-KWD
Combining BTES with Adiabatic Dry-Coolers provides a virtual Energy-Water-Nexus “slider bar” to reduce/eliminate the copious water consumption generally associated with traditional cooling towers while still exceeding water-cooled EERs
Adiabatic Dry-Cooler
Close-up of hydrophilic evaporative cooling pad/gutter at adiabatic dry-cooler coil inlet
Virtual Energy-Water -Nexus Slider-Bar
Application
Heat Reject.
COP
Air-Cooled-DX 100
BTES Max 1616
BTES Winter 200-1600
BTES Yr. Ave 200-400
Annual Water Reduction
BTES 80-100%
Energy Exchange: Federal Sustainability for the Next Decade
• 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 temperature
leaving the outer boreholes. If the system is “discharging its cold”, this represents the warmer water entering at the outer borehole
• Conversely, the green line represents the water at the core of the BTES that is entering the core during “charging” and leaving the core during “discharging”
Temperature Plots of BTES Entering and Leaving Water & Charging/Discharging Modes
Sample plot of water temperatures during cold discharging-only mode in early fall
Red shading represents “cold discharging” or heat going into the BTES (typical)
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Temperature Plots of BTES Entering and Leaving Water & Charging/Discharging Modes (continued)
Sample plot of water temperatures during DIURNAL STORAGE times in late fall (“cold-discharging” during the day & “cold-charging” at night)
Sample plot of water temperatures during continuous (24 hr/day) “cold charging” SEASONAL STORAGE mode in winter
Blue shading represents “charging”, (cold storage) or heat being removed from the BTES (typical)
Energy Exchange: Federal Sustainability for the Next Decade
Temperature Plots of Inner, Middle and Outer Borehole Delta T’s
Sample plot of water temperatures differentials across three boreholes in series charging the BTES in late fall with “cold”. The teal line is the delta T across the
inner borehole, the green the middle borehole and the blue the outer borehole. The most heat transfer is occurring exactly where it is needed
….at the core of the BTES
Energy Exchange: Federal Sustainability for the Next Decade
• KBTUs/Ft2 are down 48.1% even when this highly cooling-dominate building experienced a 14% increase in Cool. Deg. Days (CDD) and room temps kept 1°F colder. Combined annual elec., gas, water & maint. savings are $169k/year
• On-site gas consumption & emissions eliminated.
• So far, evaporative water consumption is zero…a reduction of 5.1M gallons/yr., though we may chose to consume up to 1M gallons (20% of baseline per the ESTCP Demo Plan) to lower KWH/KWD further
• Current payback on $1.8M BTES cost is 10.7 years
• “Technology Transfer”: A+ with 4 more BTES system currently under design and scheduled to bid in late 2016
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ESTCP’s EW-201135 (BTES-1) 11 month results MCLB Albany ( as of 30 June 2016)
Energy Exchange: Federal Sustainability for the Next Decade 17
Questions and Answers
Chuck Hammock, PE, LEED AP BD+C, CGD Andrews, Hammock & Powell, Inc. Consulting Engineers 250 Charter Lane Macon, GA 31210 [email protected] 478-405-8301, Ext. 6362 Skype: chuck.hammock.ahp
Session 6: HVAC Technologies -BTES