1. Comparison of Three DifferentGeoexchange Loopfields Daniel W. Felten, P.E., CGDWorld Energy Engineering ConferenceOctober 2011

2. Background ECS purchased abandonedfactory in 2007. Terraclime Geothermalbegan business operationsin 2009 Redeveloped 3rd floor(7,000 SF) for our offices Needed our firstgeothermal project to getThe Millgoing!!! Florence, MA 3. Geothermal Demonstration Site Design Industry standard U-Loop has been around fordecades. It works, but High drilling costs (150 to 200 ft of borehole per Ton) Grouting with high TC grout costly Land hog with 2 to 3 Tons (500 ft) every 20-25 ft Many competitors installing U-Loops Thermacouple and DX offered enticing claims withlimited penetration in the market 4. Thermacouple Claim:A Thermacouple earth energy systemallows theearth to exchange up to 5 tons of thermal energy 5. Reducing Drilling Requirements Kelix Thermacouple could reduce drilling depth by more than 60% (if claim true) One 306 foot Kelix can provide up to 5 Tons of heating/cooling 6. Earthlinked DX System ClaimTypically, the earth loops are 100 feet per ton ofcapacity. 7. Reducing Drilling Requirements Direct Exchange (DX) uses refrigerant in copper earth loops One ton per 100 feet of borehole 3 inch diameter borehole means quicker drilling and less grouting, less disturbance 8. Final Systems Configuration 5 Tons Direct Exchange (DX) Single stage Cu ground loops Manufacturer - EarthLinked Technologies 5 Tons Water Based U-Loop 5 Tons Water Based Concentric Tube KelixThermacouple Outside water systems interchangeable U-Loop 2 x 500 / Thermacouple 306 Water Based Manufactures: Carrier & WaterFurnace Data Acquisition using Web Energy Logger (WEL) 9. Drilling U-Loop Two 500-footboreholes, 6diameter, 1000 feettotal Bentonite sand grout HDPE Tubing 25% EtOH 2.5 days tocomplete 5 Tons Total $12/Ft = $12,000 10. Installing Loops Damaged U-LoopU-Loop Installation 11. Installing KELIX Thermacouple One 306-foot borehole, 6diameter Geo Supergrout Cementicious TC=1.0 4 diameter outer casing 1.5 days to complete recent modifications has reducedinstall time to 0.5 1 day) 5 Tons Total $14/Ft X 306 ft = $4,384 Plus, $5,500 materials Total Cost = $9,884 12. Thermacouple (Casing and Head) 13. Thermacouple Field Fabrication 14. Thermacouple Finished Wellhead 15. Drilling DX Boreholes Five 100- foot holes, 3 diameter Geo Supergrout Copper Earthloops One day to complete $2000/Ton = $10,000 16. Smaller DX Drill Rigs 17. DX Earthloop (Earthlinked) 18. Drill Tooling and DX Earthloop Copper Earthloops 19. DX Manifolds 20. DX Exposed Manifold ManifoldsFive 100 Earth Loops 21. DX Linesets (Interior) DX Linesets (Exterior)DX Installation (at the Mill) 22. Real Time Monitoring and DataAcquisition-Web Energy Logger (WEL) Real Time Monitoringand Data Acquisition Temps Pressures Flows Watts PerformanceReporting COP/EER Troubleshooting 23. Data Acquisition & Analysis Each system is instrumented at key locations Ground Loop (temps and flows) Air Handler (temps) Geo System (temps, pressures, amps) Ambient air & earth temps Data acquired at one minute intervals (NOTE:DONT TRY THIS AT HOME!) Systems were started up July 2009 24. http://welserver.com/WEL0201/ 25. DX System Performance Summary DX Modification ProgressionCOP Heat < 3 Original installation, R407c Pressure Oscillations due to component sizing mismatch, refrigerant characteristicsCOP/EER CoolingR407c changed to R22~3.3/11.3Flow control changedCooling capacity 5 Glide eliminatedTons confirmed System pressure losses remain due to distribution & volume 26. DX (Direct Exchange) 27. Mill Systems Performance SummaryWater Based SystemsWater Systems CommentsCarrier COP/EER R410a Two-Stage compressor option< 6/20+ provides max performance benefit byrejecting condensing heat @ 90F intoground @ 56F operating in 1st stageWF COP/EERR410a & Two Stage similar max benefit~6/20+North side building provides coolingadvantage 28. Water (25% Ethanol)COP3.5 4.1 (heating)5.5 6.1 (cooling)(ground systems interchangeablewith geothermal systems) 29. Thermacouple Cooling Performance 30. Comparative Analysis - Cooling 31. Normalizing Data - BTU vs. EWT U-Loop Initial EWT = 56 F Max EWT = 69 Delta EWT = 13 F over 72 minutes Total BTU Rejected = 93,000 BTU Rate = 6.5 Tons Kelix Thermacouple Initial EWT = 65 F Max EWT = 85 F Delta EWT = 20 F over 72 minutes Total BTU Rejected = 77,000 BTU Rate = 5.3 Tons50% greater EWT rise with 20% less BTU rejected 32. Normalizing Data 33. Capacity Evaluation Normalized to a Delta EWT = 13F(eg., how many BTUs does it take to get a 13 degree delta) U-Loop: 93,000 BTU (@ 6.6 Tons) Kelix:35,000 BTU (@ 5.4 Tons) Thermacouple Equivalent Capacity (relative to U-Loop) = 0.376Kelix Capacity = 0.376 X 6.6 Tons = 2.5 Tons Equivalent to 120 feet/Ton U-Loop at 152 ft/Ton Thermacouple is ~20% more efficient? 34. Is this a valid analysis? 15 minutesThese two geothermal systemsrarely cycled for 72 minutesThe majority of cycles for bothsystems were under 15 minutes 35. Its the ground, stupid We can force heat into/from the ground usingearthloop improvements The shorter the borehole, the greater the thermalgradient required The improvements are really about eliminatingborehole resistance 36. Decreasing Borehole Resistance andIncreasing Efficiency ThermacoupleGreater turbulence with lower pressure drop (reduced pumping penalty)Minimizes cross talk between inlet/outlet piping (PVC inner pipe)Better Grout: TC >1.0 vs 0.8More Conductive Casing: Fiberglass vs HDPE Direct ExchangeHighly conductive copper earthloopBetter GroutNo pumping penalty (other penalties may apply) 37. Decreasing Borehole Resistance andIncreasing Efficiency U-Loop systems work well and are easy to install DX and Thermacouple are viable alternatives forsmaller sites and/or higher drilling costs The manufacturer claims should be ignored -ground performance drives the system design Need to develop equivalent models for DX andThermacouple 38. System Comparisons