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Geothermal SystemsThe future is now

Geothermal Systems

Why is geothermalWhy is geothermal gaining 

?momentum?

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Buildings Dominate U.S. Energy Use and Carbon Emissionswith Heating, Cooling, and Water Heating being the Largest Contributors

Thermal Loads

Heating 9.2%

Cooling 4.3%

Hot Water 3.8%

Total 17.3%

~ 20% of all U.S. Carbon Emissions

Geothermal Heat Pump Systems• are the most energy‐efficient, environmentally clean, and cost‐effective space‐conditioning system

• produce the lowest carbon dioxide emissions, including all source effects, of all available space‐conditioning technologies ‐ (EPA)g g ( )

• are one of the Most Effective Ways to the Reduce Energy Consumption and Environmental Footprint of our Building Stock

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Important Because

• Energy Security of US and Australia

• Electric Grid Capacity

• Rising Energy Cost

• Climate Change / Green Movement

• LEEDS or similar Building Movementg

• Incentives by many allies

• Lowest Life Cycle Cost

The Oklahoma State Capitol uses over 600 geothermal heat pumps

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Geothermal Heat Pumps

Black Point Inn Black Point Inn ‐‐ Prouts Neck, MEProuts Neck, ME

Alta Condos, Washington DCAlta Condos, Washington DC French Laundry Rest.French Laundry Rest.‐‐ Napa, CANapa, CA

Galt House Hotel Galt House Hotel ‐‐ Louisville, KYLouisville, KYStatue of Liberty Gift ShopStatue of Liberty Gift Shop

Harvard Library Harvard Library –– Cambridge, MACambridge, MA Whistler Village Whistler Village ‐‐ BC, CanadaBC, Canada

ASHRAE Headquarters ASHRAE Headquarters ‐‐ Atlanta, GAAtlanta, GA

Commercial Buildings

Gaillardia Offices Gaillardia Offices –– Okla. CityOkla. City California University of PACalifornia University of PA Hirschfeld Towers Hirschfeld Towers –– Denver, CODenver, COYale Art Bld. Yale Art Bld. –– New Haven, CTNew Haven, CT

Geothermal Heat PumpBasic PrinciplesBasic Principles

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Earth is a Vast Solar Collector

The Earth is a Source of Heat in Winter…

Outdoor air design temperature:-15°C

23°C

18°C

Geothermal heat pumps transfer underground heat into buildings to provide heating

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…and an Efficient Place to Reject Heat in Summer

Outdoor air design temperature:38°C

23°C

18°CGeothermal heat pumps transfer heat from buildings into the ground to provide cooling

…using Heat Pump Technology

Geothermal heat pumps circulate water through a sealed underground piping loop where it is naturally warmed (or cooled) by the Earth

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Vertical Closed‐Loop Installation

Drilling Pipe LoopInsertion

Heat Fusing

InsideConnection

Thermal Conductivity TestingThermal Conductivity Testing

• Obtain:

– Local Ground Temperature

– Formation Thermal Conductivity

– Formation Thermal Diffusivity

• Not Necessary on all projects

Systems >1800m2or >100 kW– Systems >1800m2 or >100 kW

– Can save 15‐25% on installation cost

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Air Out58 F

WaterOut95 F

WaterIn

85 F

Water‐Source Heat Pumps ExchangeHeat Between Air and Water

The ground becomes the Cooling Tower and / or Boiler

Fan

WaterCoil

Air Coil

ExpansionValve

Heats or Cools on Demand

Operates on the Same Principle as a Refrigerator

Air In80 F

Compressor

ReversingValve

(Cooling Shown)

Zone HP

Ground‐Loop Heat Pump System

Ground HX

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Zone HP

Surface‐Water Heat Pump System

Submerged Heat ExchangerSubmerged Heat Exchanger

Heat Pump

Geothermal Hybrid System ‐ Summer

Water Pump

Earth Loops

Cooling Tower(ON)

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Heat Pump

Geothermal Hybrid System ‐Winter

Water Pump

Earth Loops

Cooling Tower(OFF)

Ground Energy Exchangers

• Two Primary Categories

–Closed Loop Systems

–Open Loop Systems

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Ground Energy Exchangers

• Closed Loop Systemsp y– Vertical Boreholes

• 60‐120 meters deep per borehole

• Grouted annular space between pipe and borehole

– Horizontal Loops• Straight Pipe (Residential)Straight Pipe (Residential)

• Slinky Pipes (Residential/Commercial)– Depth of Slinky pipe is directly influenced by surface conditions 

• Buried Depths are critical – 2 meters recommended

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Ground Energy Exchangers

• Closed Loop Systemsp y– Surface Water Heat Exchangers

• Critical is the surface area of body of water AND the depth of the body of water AND the seasonal temperature swings

• No real design guidelines or tools – ASHRAE has an RFP b i d l h i b d ito begin to develop the science better and gain more 

understanding

• Pipe or Plates typically used in all sorts of configurations – photos later!

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Ground Energy Exchangers

• Open Loop Systems– Check with local state(s) on acceptance and if allowed, what are requirements

– Well Water is most common source• Pump and dump

• Injection/Reinjectionj / j

– Ponds/Lakes most second common source• Caution against location of intakes and drains

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Ground Energy Exchangers

• Open Loop Systemsll d f– Well and Surface Water

• Verify through water testing is meets mfrs conditions and/or limits for particulates

– Dissolved minerals

– Precipitates

– Etc.

– Surface Water‐ Ponds/Lakes• Critical is the surface area of body of water AND the depth of the body of water AND the seasonal temperature swings

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Vertical Loop Field

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Horizontal Slinky (Pit) Loop

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Horizontal Slinky (Pit) Loop

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Horizontal Slinky (Pit) Loop

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Questions