Geothermal Heat Pump Systems Being Green by using the Ground Presented by: Warren (Trey) Austin, PE, CEM, CGD, LEED-AP Geo-Energy Services, LLC 1
Geothermal 101 Terminology Geothermal/Ground Source Heat Pump /GeoExchange General term that groups all aspects of the technology and industry together COP- Coefficient of Performance; Rating for Heating Mode- Typical Range 2.8-4.0 Output Btu/hr divided by Input Btu/hr (Unitless) Heating Btu / hr Energy Input Btu / hr 2
Ton- Capacity of Equipment (Htg or Clg) by dividing Output (Btu/hr) by 12,000 Btuhr/ton 3 Geothermal 101 Terminology EER- Energy Efficiency Ratio; Rating for Cooling Mode- Typical Range 18-27 Output Btu/hr divided by Input kw Cooling Btu / hr Energy Input kw
Geothermal 101 Terminology Continued Borehole HDPE Grout Ground Thermal Conductivity q k ground dt dt 4
How do we move energy? Remember Science or Chemistry Class? PV nrt As Pressure Increases, Temperature Increases As Pressure Decreases, Temperature Decreases 5
Geothermal Heat Pump Heating Mode 6
Geothermal Heat Pump Cooling Mode 7
Geothermal Heat Pump Heating Mode w/dhw 8
Geothermal Heat Pump Cooling Mode w/dhw 9
Space Atmosphere Passive geothermal gradient U.S. Dept. of Energy 45% absorbed by ground Earth The earth is like a solar battery absorbing nearly half of the sun s energy. The ground stays a relatively constant temperature through the seasons. 10
It s a Heat Source in Winter It s a Heat Source in Winter 0 F in winter 0 F in Winter 70 F 70 F Space Temperature Sinusoidal temperature layer Insulating of earth layer of earth 40-60 F A Geothermal Heats System the building cools the ground in winter by winter & transfers absorbing the heat into from the the building ground 40 F-60 F 2. How Does It Work? Ground Temperature 11
It s It s A a Cool Source Place to to Reject Dump Heat Heat in in Summer Summer 98 F in Summer 95 F in summer 70 F 70 F Space Temperature Sinusoidal temperature layer Insulating of earth layer of earth 40-60 F and cool the Cools building the in building summer in summer by by rejecting heat rejecting to the ground heat to the ground 40 F-60 F 2. How Does It Work? Ground Temperature 12
Applications Majority of Use Space Heating & Cooling DHW (Desuperheater or Dedicated) Mountain Regions Radiant Floor Heating (Hydronic Units) Snowmelt (Be Careful!) May Triple system requirements Special Use Process Load Water (Hot/Chilled) 13
Fossil Fuels 10-20% of heat up the flue 1 Unit of purchased fossil fuel (therm or ccf) 80-90% of heat to the building 14
Electric Resistance Heat 1 Unit of purchased electricity (100%) kwh 100% heat to the building Appears efficient, but will cost more than NG Energy Cost = $0.061/kWh 1 kwh = 3,412 Btu 100,000 Btu = therm Result: $0.061/kWh = $1.79/therm 15
Free, Renewable Energy From the Earth (Ground Source) 1.0 Unit of purchased electricity kw 3.5 Units of energy to the building for water to air, 4.5 for water to water Plus 2.5 Units of free energy from the earth for water to air, 3.5 for water to water 16
Thermal Conductivity Testing Obtain: Local Ground Temperature Formation Thermal Conductivity Formation Thermal Diffusivity Not Necessary on all projects Systems >20,000 ft 2 or >30 tons Can save 15-25% on installation cost 17
18
Thermal Conductivity Values TC Map 19
E\M Difficult Easy M/D E/M 20
Internal Component of GeoExchange Systems Air Units Horizontal HP Vertical Console Rooftop Vertical Stack Split Hydronic Units WW 22
Internal Component of GeoExchange Systems Two-Stage Compressors ECM Fans Multi-Function Dual Circuit High Temperature 23
Project Considerations Know the Design Parameters Space Heating/Cooling Air Distribution Radiant Floor Heating Hot Water/Chilled Water Integrated Systems Other Auxiliary Loads DHW Snowmelt- Heat Rejection Refrigeration Thermal Conductivity Test 24
Project Considerations Loop Fields Performance indifferent when properly designed at the same EWTs Efficiency of equipment directly correlated to EWT Pond/Lake Loops or Plates Be cautious about Icing or Overheating Horizontal Loops Sizing loop must account for frost depths, surface snow, seasonal amplitude temperature changes 25
Project Considerations Loop Fields (continued) Vertical Boreholes Least site restrictive due to greater depths for heat transfer Accounts for majority of all installation (>80%) Typical 2 and 3 header lines 2 = 4-7 boreholes per header 3 = 6-12 boreholes per header Generally like to be the lowest utility 26
Project Considerations Loop Fields (continued) Hybrid Configuration Combine any of three traditional loop field designs to help reduce cost Combine with condensing boiler/solar heating technologies in heating load dominant situations Combine with fluid coolers/cooling towers in cooling load dominant situations Due to increasing use, further research is underway 27
Project Considerations Loop Fields (continued) In certain situations, a retrofit may be site prohibitive. Combine energy efficiency improvements Previous energy efficiency improvements may PROHIBIT a feasible retrofit Consider electrical service upgrades 28
Internal Construction No Different that any other HVAC system Piping ½ Insulation only for condensation HDPE pipe for interior as potential a cost saving measure Ductwork Flex duct collars to isolate vibration Circulating Pumps Primary/Secondary Lead/Lag 29
Construction Internal (continued) Equipment Location important for sufficient access Filter Replacement Fan Motor/Housing Compressor Maintenance Mfr s Recommended Clearance- Specific Areas P/T Ports at Unit- can be integrated with hose kits Equipment Cx- Flow and Capacity 30
Additional Considerations Efficiencies of COP and EER are dependent of EWT from Loop Field EWT typically range from 30 F to 100 F Typical Operation Pressures are 25 psig to 60 psig P/T ports are critical for diagnosis & troubleshooting Use qualified/certified professionals for design and/or installation 31
Additional Considerations Service annually with filter changes every 3-6 months Suggestion for no auto-water makeup with glycol systems (residential). 32
Benefits of GSHP System 30%-60% Lower Operating / Energy Cost 40%-70% reduction in Green House Emissions 100% Site Reduction Longer life span Greater Comfort Less Maintenance, Simplified Controls Better Aesthetics (no exposed outdoor equipment) 33
Economic Feasibility Life Cycle Cost Analysis is best way to account for all variables. What are they? Installation Costs Maintenance Costs Utility Rates Escalation Factors Cost of Capital Depreciation 34
Economic Feasibility Simple Payback calculation misses so many critical factors GHEX installation cost is often 90-100% of installation cost differential If TC Test is completed, use information to obtain preliminary installation cost of GHEX Eliminate Rule of Thumb when possible 35
Economic Feasibility More upfront initial work by consultant/engineer/designer will have a significant return on investment cost down the road. Pay me now or pay them later! Who s going to be cheaper? Complexity of system integration(s) increase 36
Economic Feasibility Pre-ARRA of 2009 LCCA Installation cost ranges $18.00 to $22.00 / ft 2 Operating costs $0.45 to $0.85 /ft 2 -yr Paybacks Average: 5-8 years Can be immediate to 5 years Some systems were 8-12 years Rebates/Tax Credits Depend on local utilities- special utility rates $2000 cap Federal Tax Credit on System cost 37
Economic Feasibility Post-ARRA of 2009 LCCA Installation cost ranges $18.00 to $22.00 / ft 2 Operating costs $0.45 to $0.85 /ft 2 -yr Paybacks Average: 2-5 years Can be immediate to 2 years Some systems were 6-10 years Rebates/Tax Credits Depend on local utilities- special utility rates 30% Federal Tax Credit on System cost 38
39
40
Integration with Renewables Integration with other renewable technologies, mostly: Solar Photovoltaic/Geothermal/Wind/Biomass Solar Thermal Enhancing and merging technologies to maximize performance and reduce combined economic impacts 41
New Trends Old way of thinking no longer can meet project expectations Traditional solutions cannot apply and often creates uninspiring solutions What do I mean? 42
Traditional Approach Space Cooling Space Heating Ground Loop Heat Exchanger 43
New Trends However, biggest advances with other non-renewable technologies have opened to door to evaluating synergies if a given project 44
Heat Rejection/Absorption Synergies Space Heating Ground Loop Heat Exchanger Space Cooling Refrigeration Rejection Hot Water Heating Load Rainwater Reclaim Fluid Cooler Shallow Heat Rejection Slab Greywater Reclaim 45
New Trends These synergies now allow for larger projects without necessarily increasing the needs of a GHEX Or realizing different load profiles over a day/week/month/year can share energy in both heating and cooling modes 46
Urbanized Areas New Trends Small Market Penetration Old Concept/New Approach Non-Potable Water or Other Plate/Frame HX separation Constant 50-55 F All Year 47
48
Vertical Loop Installation Equipment Drill Rig Flushing Pipe Vertical Ground Loop Fusion Equipment Grout 49
Vertical Loop Field 50
51
53
54
Horizontal Slinky (Pit) Loop 55
Horizontal Slinky Loop 56
Centralized Slinky 57
Pond/Lake Loop 58
Pond Loop- Plate Heat Exchanger 59
Special Application 60
Vault 61
62
63
64
Commercial Heat Pump Installation 65
66
Multi-family Installation 68
Case Study 1 PSD Facility Services Building Footprint 8,900 ft 2 Installed Capacity Number of Units Total Number of Boreholes Depth Total Feet of Boreholes 25 Tons 12 Heat Pump Units 18 300 5,400 70
5/1/02 9/1/02 1/1/03 5/1/03 9/1/03 1/1/04 5/1/04 9/1/04 1/1/05 5/1/05 9/1/05 1/1/06 5/1/06 9/1/06 1/1/07 5/1/07 9/1/07 1/1/08 Energy (kwh) Demand (kw) Case Study 1 PSD Facility Services Building 8000 35 7000 30 6000 5000 4000 3000 2000 Energy (kwh) Demand (kw) 25 20 15 10 1000 5 0 0 71
Case Study 1 50 45 40 35 30 25 20 15 10 5 0 40.32 22.42 21.21 22.76 25.35 23.64 16.06 Model FY 03 FY 04 FY 05 FY 06 FY 07 FY 08 kbtu/sqft-yr 72
Case Study 1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.7 0.40 0.54 0.50 0.55 0.52 0.36 Model FY 03 FY 04 FY 05 FY 06 FY 07 FY 08 $/sqft-yr 73
Case Study 1 PSD Facility Services Building Operation and Performance E-Star Benchmark Actual Score 75 97 Energy Intensity: Site (kbtu/ft 2 -yr) 47 25 Source (kbtu/ft 2 -yr) 135 70 Emissions: CO 2 (1000 lbm/yr) 568 295 SO 2 (1000 lbm/yr) 3 2 NO x (1000 lbm/yr) 3 1 Energy Cost: Annual ($) Annual ($/ft 2 -yr) $6,519.89 $0.77 $3,391.58 $0.40 * 74
Case Study 2 USPS Shawnee, OK Retrofit Existing Post Office 100-Ton Air-Cooled Chiller 650 mbh Boiler 2 Multi-zone Constant Volume AHUs with Hot Deck/Cold Deck Heating Only in several private offices including Postmaster 75
Case Study 2 USPS Shawnee, OK Total Number of Boreholes 35 Depth 360 Total Feet of Boreholes 12,600 Htg/Clg Plant AHU CVMZ Resize CHW Coil Load Side- CV Pumping 4-20 Ton GSHP Units AHU VAVMZ CHW/HW Source Side- VS Pumping 76
3/1/98 6/1/98 9/1/98 12/1/98 3/1/99 6/1/99 9/1/99 12/1/99 3/1/00 6/1/00 9/1/00 12/1/00 3/1/01 6/1/01 9/1/01 12/1/01 3/1/02 6/1/02 9/1/02 12/1/02 3/1/03 6/1/03 9/1/03 12/1/03 3/1/04 6/1/04 9/1/04 12/1/04 3/1/05 Energy Use (kwh) Case Study 2 USPS Shawnee, OK 90000 80000 70000 60000 50000 40000 30000 20000 10000 0 Htg/Clg Baseline 77
3/1/98 6/1/98 9/1/98 12/1/98 3/1/99 6/1/99 9/1/99 12/1/99 3/1/00 6/1/00 9/1/00 12/1/00 3/1/01 6/1/01 9/1/01 12/1/01 3/1/02 6/1/02 9/1/02 12/1/02 3/1/03 6/1/03 9/1/03 12/1/03 3/1/04 6/1/04 9/1/04 12/1/04 3/1/05 Energy Demand (kw) 200 180 160 140 120 100 80 60 40 20 0 Case Study 2 USPS Shawnee, OK Htg/Clg Baseline 78
Case Study 2 USPS Shawnee, OK Pre- Post- Retrofit Change Retrofit Peak Electric Demand (kw) 182 142-22% Electric Usage (kwh) 87,840 65,700-25% Gas (Therms) 2,647 846-68% Yearly Electric Usage (kwh) 705,360 621,320-12% 79
Case Study 2 USPS Shawnee, OK 80
Internet and Literature Resources Geo-Energy Services www.geoenergyservices.com Colorado Geo-Energy Heat Pump Association www.gogeonow.org International Ground Source Heat Pump Association www.igshpa.okstate.org Geothermal Heat Pump Consortium www.geoexchange.org 81
Questions? 82