Transcript Power Point Presentation

Geothermal Heating and Cooling
Applications
Rachel Kerekgyarto
Geothermal Energy
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Thermal energy stored in the Earth
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Sources
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Solar energy absorbed in Earth’s crust
Radioactive decay at the core of the Earth
Clean, sustainable energy source
Geothermal Resources
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Three Classifications
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Low Temperature: 40oF - 100oF
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Moderate Temperature: 100oF - 300oF
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Direct-Use Heating Applications
High Temperature: > 300oF
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Widespread
Heat Pump Applications
Electricity Generation
Focus: Low Temperature
Geothermal Heating Principles
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Conventional heating systems (furnaces or
boilers) create heat
Heat pumps transfer existing heat from one
area to another
Ground temperatures are more stable than air
temperatures…Smaller Lift
Ground serves as a…
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Heat source in the winter
Heat sink in the summer
U.S. Ground Temperatures
Range: 37oF - 77oF
Changes in Ground Temperature
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Seasonal ground
temperature change
decreases with depth
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Depths greater then 20 ft: constant ground temperature
Geothermal Heat Pump System
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Three Major Components
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Ground Loop Piping System
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Heat Pump
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Circulates a fluid & serves as an underground heat
exchanger
Uses refrigerant loop to convert heat into useable heat
Ductwork
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Distributes heat throughout building
Types of Ground Loops
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Open Loops
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Open to environment
Circulate groundwater (or surface water) to the heat
pump, then discharge the water
Closed Loops
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Sealed loop of pipe in the ground or a body of water
Continuously circulates a fluid to the heat pump
Open Loops
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Well Requirements
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Water Quality Concerns
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1.5 – 3.0 gpm per ton of
heating capacity
Hardness, Acidity, Iron
Water Discharge
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Surface water
Drainage ditch
Recharge groundwater
Closed Loops - Horizontal
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Shallow Trenches
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4 – 6 ft deep
Pipe Length
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500 ft of pipe per ton of
heat pump capacity
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Land Area
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750 to 1500 ft2 per ton
Closed Loops - Vertical
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Drilled Boreholes
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Pipe Length
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Depths up to 250 ft
300 ft of pipe per ton
Land Area
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100 – 200 ft2 per ton
Closed Loops - Slinky
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Greater heat transfer in a given volume of soil
Compact or Extended Coils
Horizontal Configuration
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Uses 1/3 trench length
of a 2-pipe loop
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Vertical configuration
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Depths of 20 – 30 ft
Closed Loops – Lake
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Water Surface
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¼ - ½ acre
Water Depth
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Minimum 8 ft
Closed Loops
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Piping
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HDPE Plastic Pipe
Joined by thermal fusion
Minimum 50 yr warranty
Closed Loops
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Ground Loop Fluids
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Water: warm climates only
Antifreeze Solution
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Salts
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Glycols
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Non-corrosive, fair heat transfer, BUT toxic & viscous
Alcohols
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Non-toxic, good heat transfer, BUT corrosive
Non-corrosive, fair heat transfer, BUT toxic & flammable
Potassium Acetate
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Non-toxic, non-corrosive, more efficient
Closed Loops - Geobag
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LDPE Plastic Bag
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60 ml thick
Horizontal Configuration
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Uses 1/5 trench length
of a 2-pipe loop
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Undergoing Field Development
Closed Loop – Direct Expansion
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Direct Refrigerant Ground Loop
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Higher Efficiency
Copper Piping
Undergoing Field Development
The Heat Pump
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Refrigeration device that works backwards
Heating Schematic
The Heat Pump
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Cooling Schematic
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Domestic Hot Water Heating
Refrigerant
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R-22, an HCFC
ODP = 0.05 (Ozone Depletion Potential)
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5% of CFC-11&12 ODP
Production Phase Out 2030
Alternatives
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Blends of HFC’s – zero ODP
System Cost Comparison
Heat Pump Efficiency
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Coefficient of Performance: 3.0 - 4.0
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Produce 3 to 4 times the energy used
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40% to 60% Energy Savings
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2 – 8 year Payback on Initial Cost
Utility Rebates
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GHP’s reduce peak load
Operating Cost Comparison
Eliminating Emissions
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Galt House East Hotel
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Louisville, Kentucky
Open Groundwater Loop (58oF)
Annual Energy Savings: 5.6 mil kWh
Annual Emission Reductions
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1.8 mil lb of CO2
44,000 lb SOX
33,000 lb NOX
Conclusion
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Estimated 400,000 GHP Systems in U.S.
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Increasing Popularity
Residential & Commercial Installations
Advantages
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High Efficiency
Reduce Emissions
Renewable Resource
Economical
Constant Availability