geothermal heat pump systems
DESCRIPTION
Geothermal Heat Pump SystemsTRANSCRIPT
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Curtis J. Klaassen, P.E.Iowa Energy Center
Energy Resource Station
GeothermalHeat Pump Systems
GeoExchange Technology
Introduction
What is Geothermal Energy?
Geothermal Heat Pump System Types
Geothermal System Features● Pros and Cons● Applications
Economics and the Bottom Line
Questions at Any Time……
Geothermal Heat Pump Technology
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Energy in Buildings
Buildings Use 39% of the Nation’s Primary Energy
21%
18%
33%
28%
ResidentialCommercialIndustryTransportation
Total Residential = 21%
Total Commercial = 18%
Energy Efficiency – Building BlocksStep 1 – Reduce Energy Load● Site Orientation and Building Arrangement ● Efficient and Effective Building Envelope
Step 2 – Improve Efficiency of Systems and Equipment● HVAC Systems – Geothermal Systems● Efficient A/C units, Boilers, Motors, Light Fixtures● Lighting Systems – Daylighting● Computers and Office Equipment
Step 3 – Effective Building Operations● Proper Control – Energy Management Systems● Commissioning ● Operations and Maintenance – Training and Support● Leverage Utility Company Rate Schedules
Step 4 – Alternative Energy Sources● Renewable Energy Options – Solar, Wind, Biomass
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What Is Geothermal Energy?Geothermal Energy is defined as “energy from the internal heat of the earth”
● 47% of the incoming radiation from the sun is absorbed by the earth
● The remainder is absorbed by the atmosphere or reflected back into space
Translated: Geo-Thermal means “Earth-Heat”
“High Temperature” Geothermal Energy● Energy Source for Hot springs and geysers● Temperatures exceed 300°F● Converted to produce useable heat and electricity
“Low Temperature” Geothermal Energy
Heat Energy contained near the surface of the Earth
Shallow Earth temperatures fluctuate with seasonal outside air temperature
Earth temperature becomes more stable with increasing depth
Nearly constant Earth temperatures at depths below 16 feet
Earth mean temperature approaches annual average outside air temperature
Deep Earth temperatures start to increase at depths below 400 feet-- at about 1 °F per 100 feet
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Low Temperature Geothermal Energy
Geothermal Heat Pump Systems● Take advantage of “Low Temperature” Geothermal Energy
● Constant Temperature Year Around – 47 to 50°F in Michigan● Apply a Water Source Heat Pump to “amplify” the heat energy
AKA● Ground Source Heat Pumps● Earth Coupled Heat Pumps● GeoExchange Systems● Well/Ground Water Heat Pumps● v.s. High Temperature Geothermal
Characterized by Medium used for Heat Source and Heat Sink● Air to Air or Air Source● Water to Air or Water Source● Water to Water● Ground Source or Geothermal
Capable of Heating, Cooling and producing Hot Water● Capacity measured in tons● One ton of capacity = 12,000 BTU per hour (Cooling or Heating)● Typical new home is about 4 – 5 tons of heating capacity & 2 tons cooling● Typical Classroom is about 2 – 3 tons of heating or cooling capacity
What are Heat Pumps?
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Geothermal Heat Pump System
Heating/Cooling Delivery System● Traditional Ductwork / Piping system to deliver
heat throughout the building
Heat Pump● Mechanical Unit that moves heat from the working
fluid, concentrates it, and transfers the heat to the circulating air
Ground Heat Exchanger● Underground piping system that uses a working
fluid to absorb or reject heat from the ground
Three Basic Components:
GeoExchange System TypesClosed Loop System● Buried HDPE Piping● Underground Heat Exchanger ● Circulating Fluid contained● Exchanges only Heat with
the Ground● Various Configurations
Open System● Ground Water from Well● Exchanges Heat and Water with
the Ground● Returns Water to the Ground
Special Systems● City Water Interconnect Systems● Hybrid Systems
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Horizontal Trench LoopCost effective when land area is plentiful
Needs 2500 square foot Land area per ton
Trench depth – Six feet or moreGEOTHERMAL PIPE
To Produce 1 ton of capacity:● Trench length – typically 300 feet● Pipe length – out & back = 600 feet
Courtesy IGSHPA
Courtesy IGSHPA
Horizontal Trench Configurations
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2 inch Headers
3 Circuits
Horizontal Loop
Three Circuits – each with Four Trenches and 4 pipes in each trench
Nominal 24 Ton Configuration
12 Horizontal Trenches Each 300 foot long with Four ¾ inch pipes
Slinky Loop
Slinky Coil – Overlap
Slinky Coil – Extended
To Produce 1 ton of capacity:● Trench length – typically 125 feet● Pipe length – out & back = 700 feet
Courtesy IGSHPA
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Vertical Bore LoopKeeps Space required to a minimumNeeds 250 Square Feet Land area per tonBore Depth – 100 to 300 feetBore Diameter – about 4 to 5 inchesBore Spacing – 15 to 20 feet apart Nominal Capacity – One ton / 200 ft Bore Hole
Vertical Bore Grouting
Grouting of Vertical Bore Holes Required
● Seal Borehole to Protect Underground Aquifers
● Maintain Thermal contact between pipe and ground
● Allow movement of pipe
Grout Types● Bentonite Based● Thermally Enhanced ● Cement Based
Pressure Grouting from the bottom up recommended
Courtesy ASHRAE GSHP Engineering Manual
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Vertical Loop
2 inch Header Pipes
Nominal 24 Ton Configuration
200 foot Deep Vertical Bores with ¾” Pipes
3 Circuits with 8 Bores each Circuit
Horizontal Boring
Horizontal / Directional Boring Machine used
● Horizontal length typically 200 feet for one ton of capacity
● Bore depth controlled at 15 feet
● Setup from one ‘hub’location for multiple radial bores
● Minimal disturbance to topsoil and landscaping
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Pond Loop
Most Cost Effectiveclosed loop design
Pond Depth – 12 – 15 ft minimum maintained depth
Pipe Length – One 300 ft. coil per ton (minimum)
Capacity – 10 to 20 tons/acre of pond
2 Tons
3 Tons
4 Tons
Pond Loop
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Pond Loop Installation
Open Loop
Very Cost Effective, providing the following are verified:● Water Quality is High
● Water Quantity is Sufficient
● Meets Codes and Regulations
AKA “Pump and Dump”● 1.5 to 2 GPM per ton required● At 30% run time a 4 ton unit could use
100,000 gallons per month
● Typical Family of Four uses about 6,000 gallons per month for domestic purposes
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GeoExchange System Types
Special Systems● Standing Water Well
− Extraction and Rejection to the same well− Concentric Pipe – Return water on Outside Pipe− Bleed off water for temperature control
● Interconnection to City Water Mains− Extract heat from water mains with heat exchanger− Return water to water mains downstream
Hybrid Systems● Coldest days -- use auxiliary heat source● Hottest days -- supplement with cooling tower
EnergyPros and Cons
GeoExchange System Features
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GeoExchange System FeaturesEnergy Pros+ GeoExchange Heating Contribution
● 1 kW electricity plus 3 kW geothermal heat moved from the earth = 4 kW heat delivered
● Heating COP of 3.5 to 4.9
+ GeoExchange Cooling Contribution● Earth temperature sink cooler than air temperatures
= reduced cooling compressor work● Cooling EER of 14 to 27 (on 2 speed units)
+ Individual units allow zoning for off hour use
+ Reduced site energy consumption: 30% - 50% less
+ Lower energy costs: 20% - 30% less
GeoExchange System Features
Energy Cons− Economizer Free Cooling not normally available− Ventilation/make up air energy handled separately
Energy Considerations= EER and COP include allowances for fan and pump energy
= Distinction between EER and SEER
= Minimize Circulating Pump energy
= Water to Water Heating Options
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Energy Considerations
Heat Pumps – Ground Source● Heating Efficiency measured by COP (Coefficient of Performance)● Cooling Efficiency measured by EER (Energy Efficiency Ratio)● Efficiency measured at Specific Temperatures and Conditions
What are the Actual Entering Water Temperatures?
2.9
3.6 +
4.9
Closed LoopCOP @ 32°F EER @ 77°F
10.6
16.0 +
27.0
11.83.1Low Efficiency
20.0 +4.6 +High Efficiency
31.15.5Best Available
Open LoopCOP @ 50°F EER @ 59°F
Efficiency RatingARI / ASHRAE / ISO 13256 - 1
M T W T F S S
70°F
GeoExchange System EWT – Summer
EER = 20
EER = 16
15
-15
-10
-5
0
5
10
15
20
25
30
35
40
45
50
Sunday,January 25,
2004
Monday,January 26,
2004
Tuesday,January 27,
2004
Wednesday,January 28,
2004
Thursday,January 29,
2004
Friday,January 30,
2004
Saturday,January 31,
2004
Tem
pera
ture
- D
eg F
GeoEx_LWST GeoEx_LWRT OA_Temp
Outside Air Temp
Supply Temp
Return Temp
40.0 Deg F
34.6 Deg F
GeoExchange System EWT – Winter
IAMU GLSWT vs. GLRWT (day average): 2001
40
45
50
55
60
65
70
1/1 1/31 3/2 4/1 5/1 5/31 6/30 7/30 8/29 9/28 10/28 11/27 12/27
Year 2001 Date
Tem
pera
ture
(Deg
F)
GLSWT GLRWT
48°F
64°F
GeoExchange System EWT -- Annual
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Energy ConsiderationsCirculating Pump Energy● Pumping Energy Can Be Significant due to 24 / 7 Load Factor
● Minimizing Pump Head effective ● Many Geothermal Systems have excess Pumping Energy
● Circulating Pump Monitored Energy Use:− Represents 8 % of the HVAC Metered Peak Demand
− Consumes 36 % of the Total Building HVAC Energy
− Responsible for 18 % of the Total Building Energy Costs
Evaluate Pumping Options● Decentralized Loop Distribution
● Two stage parallel pumping
● Variable Flow pumping w/VFD’s
Energy ConsiderationsASHRAE Technical Paper●“Energy Use of Pumping Options for Ground Source Heat Pumps”
An ASHRAE Technical Paper by Stephen Kavanaugh, PhD. and Sally McInerny, Ph.D.,P.E.
0
20000
40000
60000
80000
100000
120000
Constant Speed Primary /Secondary
Variable Speed DecentralizedLoop Pumps
AnnualPumpEnergykWh
Evaluated Energy Consumption of 4 Pumping Systems• Constant Speed• Primary / Secondary• Variable Speed Drive• Decentralized Pumping
Majority of Savings due to the ability to cycle off pumps during unoccupied hours and lower pump head requirements
108,600
65,500
18,800 13,100
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Energy Considerations
Pump Energy Report CardBy Stephen Kavanaugh, PhD
F – Bad 15 or More
D – Poor10 to 15
C – Mediocre7.5 to 10
B – Good5 to 7.5
A – Excellent5 or Less
GradePump Power per 100 tons
Operation and Maintenance
Pros and Cons
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Operation and Maintenance Pros+ Unitary equipment – failure of one unit
+ Simple, not complex – Reduces Service Contracts
+ Avoids Boiler, Condensing Units or Cooling Towers
+ Elaborate Control Systems not required
+ No annual Boiler Teardown and Inspections
GeoExchange System Features
GeoExchange System Features
Maintenance and Operations Cons− Quantity of units to maintain− Air filters and drain pans (unitary)− Heat pump locations accessible
Maintenance Considerations= Refrigerant 22 vs 410A
= Equipment/compressor service life of 19 years
= Looping piping service life of 50 + years
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Environmental
Pros and Cons
GeoExchange System Features
Environmental Pros+ More comfortable indoor environment
> Each unit operates independently, allowing either heating or cooling to occur as required
> Individual Room Control of Heating or Cooling
+ No Make-Up Water for Boiler / Cooling Tower
+ No Chemical Treatment / Hazardous Materials
+ Eliminate Carbon Monoxide (CO) Potential
+ No Vandalism or Security Concerns
+ Minimal floor area required
+ Less energy means less natural resources and less pollution
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GeoExchange System Features
Environmental Cons− Noise inside building
Environmental Considerations= Selection of Circulating Fluids
= Temporary disturbance of landscaping
= Design for proper indoor air quality
Where does a GeoExchange System
Apply?
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GeoExchange Applications
New Construction● Integrate GeoExchange into design● Optimize system efficiency and costs
Retrofit Construction● Air condition existing non A/C building
● Replace Unit Ventilators or Fan Coil Units
● Minimum disturbance for Historical Preservation
GeoExchange Applications
Building Type● Good application:
− Single-story – finger plan
− Balanced envelope / interior thermal loads
● Weak application:− New well insulated multi-story “box” with high internal loads
● Residential− Excellent application
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GeoExchange Applications
Schools are Good Candidatesfor GeoExchange Systems
Retrofit older systems
Air conditioning upgradeSchool building layout normally good for balanced
heating/cooling loads
Typical classroom good economic size for heat pump
Open field area available for Geothermal Heat Exchanger
System advantages attractive to schools
Schools will be around to enjoy the life cycle cost benefits
GeoExchange Applications
Domestic Water Heating Applications● Desuperheater kit to heat domestic water – Standard Option
− Cooling Season = Free water heating− Heating Season = High COP water heating
● Water to water heat pumps preheat Domestic Water at a COP of 3.0 – 5.0
Water to Water Heat Pump Applications● Hydronic systems
● Radiant floor systems
● Heating water/chilled water source for Outside Air/ Ventilation Air with conventional air handling systems
● Swimming Pool water heating
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Radiant Floor Heating Application
Radiant Floor
● Circulate heated water through piping circuits embedded in floor slab
● Warm Floor radiates heat to the walls, ceiling and other objects
● Water to Water Heat Pumps provide water at an effective temperature
Geothermal System Economics
$ First Costs+ Energy Costs
+ Maintenance Costs
= Bottom Line
What is the Cost Experience?
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First Cost BasicsBuilding and HVAC System Criteria drive Costs● Building Type, Occupancy and Use● Thermal Zones and Ventilation Requirements● HVAC Equipment Space Allocation● Central System vs Distributed / Unitary System
Generally, the Geothermal system cost inside the building is less than or equal to conventional system
Incremental cost of a Geothermal Heat Exchanger vs● Boiler and Heating Water Pumping systems● Chiller / Cooling Tower and related Pumping systems● Condensing Units / Rooftop Units
First Cost is greatly influenced by Effective Design
First Cost Considerations
Manage the Installed Cost● Reduce the total Heating / Cooling Load
− Efficient Building Envelope− Outside Air Loads: CO2 / DCV and Energy Recovery Units− Recognize System Load Diversity
● Field Test for actual Soil Thermal Conductivity
● Organize and Minimize Geothermal System Piping
● Control the Control System Costs
● Experience based evaluation of System Design
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First Cost Considerations
Recognize All System Related Cost Savings
● Boiler Stacks and Roof Penetrations
● Boiler Room Combustion Air
● Chemical Treatment, Make Up Water and related equipment
● Structural Cost for Cooling Tower or Equipment Support
● Screen Walls and Fences for Vision, Vandalism, Security
● Machine Room (Refrigerant) Ventilation
● Natural Gas Service Entrance
● Reduced Mechanical Equipment Floor area
First Cost ConsiderationsUtility Company Incentives● $ 0 to $ 600 per ton● Custom Incentive Programs● Alternate Rate Schedules● Check with the Local Utility before Design
Financing Options● Energy Savings or Performance Contracting ● Utility Company Financing
Tax Incentives● Up to $1.80 per SF for 50% better than Energy Standard● Up to $300 Tax Credit for Residential Geothermal Heat Pumps
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First Costs – GeoExchange Bore FieldUnit Cost Summary – 14 Buildings
Gross Bore Field Cost Range Average
Cost per Square Foot: $ 1.88 – $ 4.55 $ 3.27 / SqFt
Cost per Ton: $ 715 – $ 2,817 $ 1,719 / Ton
Cost per Bore: $ 775 – $ 3,032 $ 1,537 / Bore
Cost per Foot of Bore: $ 4.43 – $ 12.50 $ 7.83 / BoreFt
These are project reported construction costs ● The costs are not qualified for scope or normalized for conditions● Costs do not include Credits for Boilers, Chillers, Cooling Towers● Costs do not include Utility Company Incentives● Additional Project Cost Information appreciated
First Cost Examples
West Liberty High School
● New High School 78,000 GSF with 280 tons cooling capacity
● Horizontal Bore Installation Alternate bid
● 112 Horizontal Bores at 500 feet long
● Horizontal Bores stacked two high
● $363,000 for Horizontal Bore Field piped to Building
● $3232 per bore / $6.46 per bore foot
● Vertical Bore arrangement bid at $160,000 more (44% increase)
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Energy Costs
Energy Costs
All Electric / Electric Heat Rate Schedule● Significant Factor for Energy Costs● Identify the applicable Rate Schedule● Electric Costs of 4 ¢/KWH electric heat vs. 8 ¢/KWH for winter use● Some Rates may be applied to the total building electrical use● Net Heating Energy Costs of $4/MMBTU vs. $12/MMBTU
Electrical Demand● Typical Reduction in Electrical Demand● Demand Limiting / Load Shedding Opportunities ● Demand may be a significant factor in total electric costs
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Energy Costs
Case Studies – Three Ankeny Elementary Schools
● Actual Site Energy Reduction: 46% to 54% BTU/SF-Yr
● Actual Energy Cost Reduction: 6% to 14% $/SF-YrNon Air Conditioned to Air Conditioned
● Energy Cost Avoidance: 20% to 34% $/SF-Yr
Operation and
Maintenance Costs
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Maintenance Costs
ASHRAE Technical Paper
● “Comparing Maintenance Costs of Geothermal Heat Pump Systems with Other HVAC Systems: Preventive Maintenance Actions and Total Maintenance Costs”A Technical Paper prepared for ASHRAE by Michaela A. Martin, Melissa G. Madgett, and Patrick J. Hughes, P.E.
● Project focus – Lincoln Public School District, Lincoln, NE− 20 School buildings and 4 HVAC System types were evaluated
− Maintenance Costs summarized by:> Preventive Maintenance Costs per SF per Year> Repair, Service, and Corrective Action Costs per SF per Year> Total Maintenance Costs per SF per Year
Maintenance CostsLincoln Schools, Lincoln Nebraska
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Economic Performance
Bottom Line
● Most Energy Efficient Heating & Cooling System Available
● Comfortable with a High Degree of Owner Satisfaction
● Reduces Energy Cost by 20% to 35%
● Adds 2 – 4% to the Total Cost of New Construction
● Incentives, Credits and Alternate Financing may be Available
● Typical 5 to 10 year payback
● Generally best Life Cycle Costs
Each Commercial Facility is Unique
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GeothermalHeat Pump Technology
Thank You…….. Discussion ! ! ! !
Questions ????
Iowa Energy Center / Energy Resource StationPhone: 515-965-7055
Geothermal Heat Pump Systems
Well Construction Considerations and Permit Regulations Affecting Geothermal Heat Pump Systems
Rising energy costs have generated increased interest in geothermal heat pump
systems (GHPS). According to the U.S. Environmental Protection Agency, GHPS can save homeowners 40-60 percent in heating and cooling costs, over conventional HVAC systems. Geoexchange technology reduces greenhouse gas emissions and household safety hazards associated with fossil fuel combustion. High performance commercial building designs regularly incorporate geothermal technology to reduce energy costs.
A GHPS using either a water well supply or return well for the disposal of used water
requires a well construction permit issued by the local health department. Depending on the particular GHPS design, additional permits may be needed from the Department of Environmental Quality (DEQ).
The last page of this document contains a decision tree flowchart describing when and
what types of DEQ permits may be required.
Definitions 1. Geothermal Heat Pump System - a mechanical device, also known as a ground
source heat pump or geoexchange system, which uses the geothermal exchange properties and the relatively constant temperature of earth formations for heating or cooling a building space. A GHPS consists of three parts: 1) heat pump unit, 2) heat exchanger, and 3) heating/cooling distribution system (e.g., duct work).
2. Closed-Loop - a geothermal heat exchanger that circulates a nontoxic antifreeze
heat transfer fluid through a loop or multiple loops of polyethylene piping installed below the ground surface or within a surface water body. Unlike an open-loop, a closed-loop heat exchanger does not involve the withdrawal of groundwater. The earth's heat is absorbed by the heat transfer fluid within the loop piping and transmitted to the heat pump unit's heat exchanger and compressor to provide heating. In the summer, the cycle is reversed and the GHPS removes heat from the building and transfers it into the earth.
3. Open-Loop - a geothermal heat exchanger that withdraws groundwater from a
supply well, passes the groundwater through a heat pump, and discharges the temperature-altered water either back to the ground in a discharge (return) well or to the ground surface or into surface water. Typically, the temperature is altered 4 to 10 degrees. In smaller residential settings, a single drinking water well may supply groundwater for both the GHPS and standard domestic uses.
4. Direct Exchange – a type of closed-loop heat exchanger that uses loops of copper tubing installed in pits, trenches or vertical borings in the earth, through which a refrigerant is circulated.
MICHIGAN DEPARTMENT OF ENVIRONMENTAL QUALITY Environmental Assistance Hotline Jennifer M. Granholm, Governor • Steven E. Chester, DEQ Director 1-800-662-9278 www.michigan.gov/deq May 2007
Geothermal Heat Pump Systems Page 2 of 8
5. Well - an opening in the surface of the earth for the purpose of removing fresh water or a test well, recharge well, waste disposal well, or a well used temporarily for dewatering purposes during construction (From Section 12701 of the Public Health Code). R 325.1606(3) of the well code further defines a well to include water supply wells, irrigation wells, heat exchange wells, and industrial wells.
6. Heat Exchange Well – a well used for the purpose of utilizing the geothermal properties of earth
formations for heating or air conditioning (From R 325.1606(3) of the well code). 7. Standing Column Well – a semi-open-loop heat exchanger consisting of a vertical boring from
which groundwater is withdrawn and into which groundwater that has passed through a GHPS is discharged.
Regulatory Authority
Depending on the specific type of heat exchanger, the owner or installer of a GHPS may be subject to the following state or federal regulations: a. Well Construction Code Part 127, Water Supply and Sewer Systems, 1978 PA 368 (Public Health Code), as amended, (MCL 333.12701 et seq.) and the administrative rules comprising the Michigan Water Well Construction and Pump Installation Code (state well code) (R 325.1601 et seq.), provides a mechanism to protect groundwater by regulating the construction and abandonment of water supply wells, water discharge wells (or return wells), and standing column wells needed for some GHPS. Closed-loops associated with a GHPS are not regulated under the state well code. b. Discharges to GroundwaterDischarges to groundwater are regulated under Part 31, Water Resources Protection, 1994 PA 451, Natural Resources and Environmental Protection Act (NREPA), (MCL 324.3101 et seq.) and Part 22 Rules (R 323.2201 et seq.). c. Discharges to Surface WaterNational Pollutant Discharge Elimination System (NPDES) surface water discharge permits are authorized by the 1972 amendments to the Federal Clean Water Act, Public Law 92-500, as amended, and the rules promulgated thereunder. Michigan has primacy to issue NPDES permits through Part 31 of NREPA, and promulgated rules. d. Water Use ReportingPart 327, of NREPA (MCL 324.32701 et seq.) establishes requirements for the reporting of water use. e. Underground Injection ControlThe federal Underground Injection Control (UIC) regulations are within Part C, Sections 1421-1426, Safe Drinking Water Act, passed by Congress in 1974. Michigan is not UIC primacy state. The federal UIC program is implemented directly by the U.S. Environmental Protection Agency, Region V, Chicago, Illinois. f. Other Laws and Regulations In addition to DEQ regulations, other state permits, such as mechanical, electrical, and plumbing are needed. Ordinances of some local units of government may have provisions pertaining to GHPS installations. Be sure to check with local officials and comply with all applicable local requirements.
Geothermal Heat Pump Systems Page 3 of 8
Permit Requirements and Construction Advisory for Closed Loop GHPSs Boreholes for the installation of a vertical closed-loop may extend several hundred feet in depth. Since vertical closed-loops and direct-exchange loops may penetrate drinking water aquifers, it is critical that loop boreholes be properly grouted to protect drinking water. Sealing the space between the vertical loop piping and borehole from the bottom up to the ground surface with an appropriate low permeability grout, as recommended by the GHPS manufacturer and consistent with the state well code, is strongly advised. Thermally-enhanced bentonite grouts, designed to enhance closed-loop performance, are acceptable if the permeability of the set grout seal is 1 X 10-7 centimeters per second or lower. Grout must be placed from the bottom of the loop borehole up to the surface through a grout pipe. The grout pipe should be withdrawn as the grout reaches the surface. Drill cuttings should not be shoveled into the borehole. The DEQ advises that loop boreholes be constructed by Michigan registered water well drilling contractors. Since closed-loops do not extract groundwater, the DEQ does not have authority to regulate their installation under the well code. Certain provisions within the Michigan Residential Code (MRC), implemented by the Michigan Department of Labor & Economic Growth, Bureau of Construction Codes & Fire Safety, apply to GHPS closed loop piping. Section M2104.2.1 sets forth minimum standards for heat fusion, electrofusion and stab-type insert fittings for the joining of polyethylene piping and tubing. Section M 2105.1 has minimum criteria for pressure testing of the assembled loop system before backfilling. Pressure testing is required with water at 100 psi for 30 minutes with no leaks observed. Refer to the MRC for further details. Closed-loops are installed either horizontally in ground trenches, vertically in a borehole, or submerged within a large pond or lake. Since the length of the closed-loop piping depends on the heating/cooling load of the building, large GHPS often use a series of vertical closed-loops interconnected by header piping. Several dozen boreholes of several hundred feet in depth may be needed. If a closed-loop is proposed to be installed within a pond, lake, river, an NPDES discharge permit may be required pursuant to Part 31, NREPA. To inquire whether a permit is needed or to apply for a permit, contact a DEQ district office or the DEQ Permits Section, Water Bureau in Lansing. A DEQ permit will be required prior to construction if the GHPS heat exchanger is installed in a wetland, floodplain, river, lake or critical dune area. Also, if the heat exchanger installation will disturb more than 1 acre of land or is within 500 feet of a water body, a soil erosion permit (as required by Part 91, Soil Erosion and Sedimentation, NREPA, MCL 324.9101 et seq. and R 323.1701) must be obtained from the appropriate county soil erosion agency. Because the fluid within a closed-loop heat exchanger does not directly contact the environment, a closed-loop is not considered a Class V well under the federal Underground Injection Control (UIC) regulations (40 CFR 144.3). The location of trenches and boreholes for GHPS closed-loops should be well documented and recorded. Future excavation, without knowledge of loop locations, can result in damage and spillage of heat transfer fluids into the environment and interruption of building heating or cooling.
Geothermal Heat Pump Systems Page 4 of 8
Permit Requirements and Construction Advisory for Open Loop GHPSs An open-loop GHPS can be installed in a variety of formats. In all cases, the supply well must be constructed in accordance with the GWQC rules and a well construction permit obtained from the local health department, where required under local ordinance. Additionally, the supply well must be constructed by a Michigan-registered water well driller, and the pump installed by either a Michigan-registered water well driller, pump installer or a licensed master plumber. In addition to well construction permits, any open-loop system installed in a wetland, floodplain, or critical dune area, will require a permit from the DEQ, Land & Water Management Division. The owner of an open-loop GHPS installed for commercial purposes, that uses a water well having the capacity to withdraw 100,000 gallons of water per day over any 30-day period, must report water use to the state of Michigan. Water withdrawal capacity of 100,000 gpd is equivalent to 70 gallons per minute. Registration is based upon the total pumping capacity of a facility's water system, regardless of how much water is actually withdrawn during a given year. A $200.00 annual filing fee is required. Water use is reported to the DEQ Water Bureau. Agricultural water users have the option of reporting to the Michigan Department of Agriculture or to the DEQ. Large quantity (over 70 gpm) open-loop GHPS owners should contact the Water Use Reporting Program, DEQ, Water Bureau, for further details. 1. Open-loop systems discharging to the groundwater through a discharge (return) well.
A local health department permit may be required for the discharge well, depending on the local well permitting ordinance. The discharge well must be constructed by a registered well driller in accordance with the state well code. A DEQ groundwater discharge permit will also be required if either of the following conditions are present:
a. There is chemical addition to the GHPS. b. The GHPS has a rating greater than 300,000 Btu/hr.
The isolation distance between the GHPS supply and discharge wells should be based on the heat pump unit manufacturer’s recommendations to minimize thermal interference effects on system efficiency. If possible, the discharge well should be located down gradient of both the geothermal water supply well and any drinking water supply well. The DEQ advises a minimum of 50 feet between the supply and return well, unless specified by the GHPS unit manufacturer. Potable water supply wells should be isolated from GHPS discharge wells a minimum of 50 feet if the discharge water has no chemical additives. If chemical additives are used, the potable water supply well should be a minimum of 300 feet. Deviations from the minimum isolation distance provisions may be granted by the local health department in accordance with R 325.1613 of the well code. The discharge of water within a return well should occur below the static water level in a manner that prevents the injection of air into the return well. Premature well plugging from precipitated ferric iron solids and biofouling may occur if air is introduced. GHPS discharge wells should be designed to discharge water back into the same aquifer from which the supply well withdraws groundwater to ensure that the quality of the discharged water does not degrade the quality of a drinking water aquifer. An open-loop GHPS equipped with a well for discharging heat pump water back into an aquifer is considered a Class V well under federal Underground Injection Control regulations (40 CFR 144.3). The EPA may require a permit for a heat pump return well.
Geothermal Heat Pump Systems Page 5 of 8
The use of chemical additives (such as biocides, algicides, or anti-scaling agents) would render the water unsuitable for discharge into the same aquifer as the heat pump supply aquifer. In such cases, the DEQ, Office of Geological Survey (OGS), Mineral Well Program, would require a deep injection well permit under Part 625, Mineral Wells, NREPA. Additionally, if the heat pump supply well withdraws groundwater from a brine-bearing aquifer, the OGS requires a permit for both the supply and discharge (return) wells.
2. Open-loop system discharging to groundwater through an infiltration gallery similar to a common septic system drainfield. Either a local health department on-site wastewater permit or a DEQ discharge-to- groundwater permit may be required depending on local codes and the amount of daily flow. Also, a DEQ discharge to groundwater permit is required under Part 31, NREPA, if there is chemical addition to the GHPS or if the GHPS rating is greater than 300,000 btu/hr.
3. Open-loop system discharging to the open ground surface with eventual infiltration. This type of disposal is allowed, but property owners need to be aware of the potential for nuisance conditions to be created. Based on site factors, such as soil conditions, topography, and the volume of water to be discharged, problems of soil erosion, sedimentation, freezing, or migration onto adjacent property, roadways, or drainage ditches may occur.
4. Open-loop system discharging to a surface water body
According to a Water Resources Commission 1980 policy statement, heat pump installations for single-family residential use are typically low-volume discharges, particularly in the cooling mode with not more than five-to-six gallons per minute and maximum temperatures of 90 to 95 degrees Fahrenheit. Flows for the heating mode are five-or-six times greater, but with temperatures below 50 degrees Fahrenheit. Based upon these characteristics, and further that a large system for single-family residential use will be rated at not more than 120,000 BTU per hour; the Water Resources Commission expected that discharges to the groundwater or to surface water courses from such systems should have minimal impact on water quality. The Water Resources Commission policy statement (January 24, 1980) specifically stated:
". . . heat pump facilities with a heat exchange capacity of 120,000 BTU per hour or less will not be required to have a discharge permit provided there are no chemical additives used in the system."
Most residential systems are not required to have a permit under this policy statement. However, if the use of additives is proposed or the heat exchange capacity exceeds 120,000 BTU per hour, then an application for discharge should be filed.
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Local Health Department Role
Local health departments play both advisory and regulatory roles regarding GHPS installations. In addition to the normal work done to permit a drinking water well for a facility, local health department personnel need to recognize the ground water resource protection issues associated with GHPS. If the proposed GHPS possibly needs a DEQ permit, the local health department staff should advise the owner or contractor accordingly. Through contract with the DEQ, local health departments have a regulatory responsibility to implement the state well code and issue local well construction permits. R 325.1606(3)(c) in the well code provides the authority to regulate the construction of water supply wells supplying GHPS. Section 12701(d) of the Public Health Code provides the authority to regulate construction of the geothermal discharge well. For further guidance, local health department staff should contact the DEQ, Well Construction Unit, Drinking Water and Environmental Health Section, Water Bureau, in Lansing at 517-241-1374, or by fax at 517-241-1328.
GHPS Installer Training Water well drilling contractors interested in GHPS educational opportunities should contact the International Ground Source Heat Pump Association (IGSHPA) and National Ground Water Association (NGWA). The IGSHPA offers installer accreditation after completion of a workshop and exam and the NGWA sponsors a conference focusing on geothermal industry opportunities for well drillers.
Information Sources
Several agencies and organizations have internet websites containing useful information about geothermal technology. Among them are:
1. American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE), at www.resourcecenter.ashrae.org
2. Geothermal Heat Pump Consortium, Inc., at: www.geoexchange.org
3. International Ground Source Heat Pump Association, at: http://www.igshpa.okstate.edu
4. Michigan Geothermal Energy Association (MGEA): www.earthcomfort.com
5. U.S. Department of Energy, Energy Efficiency and Renewable Energy, Geothermal Technology Program at: www.eere.energy.gov/geothermal
6. The Class V Underground Injection Control Study, Volume 19, Heat Pump and Air Conditioning Return Flow Wells, U.S. Environmental Protection Agency, Office of Groundwater and Drinking Water, (4601) September 1999, EPA/816-R-99-014s. The document can be viewed at: www.epa.gov/ogwdw/uic/classv/pdfs/volume19.pdf
7. Michigan Residential Code, Incorporating the 2003 edition of the International Residential Code for One- and Two-Family Dwellings, 2003, Copies are available from the Michigan Department of Labor & Economic Growth, Bureau of Construction Codes & Fire Safety, PO Box 30255, Lansing, MI 48909 at a cost of $45.00.
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8. Ground Source Heat Pumps, The Energy Observer, Quarterly Issue – June 2005, The Energy Office, Michigan Department of Labor & Economic Growth, PO Box 30221, Lansing, MI 48909, available at: www.michigan.gov/documents/EO_06-05_131159_7.pdf
9. Energy Star, Joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy, at: www.energystar.gov/index.cfm?c=geo_heat.pr_geo_heat_pumps
10. Guidelines for the Construction of Vertical Boreholes for Closed Loop Heat Pump Systems, 1997, National Ground Water Association, 601 Dempsey Road, Westerville, OH, 43081-8978.
11. PPI Handbook of Polyethylene Pipe – HVAC Applications and Statement Q, Plastic Pipe Institute Position Statement on Polyethylene Materials For Closed-Loop Refrigeration and Heating Applications, The Plastic Pipe Institute, at www.plasticpipe.org.
PERMIT DECISION FLOWCHART FOR GEOTHERMAL AND HEAT EXCHANGE SYSTEMS
____________________________________________________________________________________________
CLOSED LOOP SYSTEM ?
PART 127 RULES DO NOT APPLY
OPEN LOOP SYSTEM WITH CHEMICAL ADDITION ?
PART 127 RULES APPLY TO WATER SUPPLY WELL
DISCHARGETO GROUND WATER ?
PART 127 RULES APPLY TO WATER SUPPLY WELL
SURFACE WATER DISCHARGE
PART 127 RULES APPLY TO DISCHARGE WELL
DISCHARGE TO GROUND WATER ?
SURFACE WATERDISCHARGE RATED ABOVE 120,000 BTU/Hr ?
DISCHARGE PERMIT NOT REQUIRED (1)
NPDES PERMIT MAY BE REQUIRED (1)(2)
GROUND WATER DISCHARGE PERMIT MAY BE REQUIRED (2)HEAT
EXCHANGE UNIT RATED ABOVE 300,000 BTU/Hr ?
GROUND WATER DISCHARGE PERMIT NOT REQUIRED
NPDES DISCHARGE PERMIT MAY BE REQUIRED (1)(2)
(1) If any portion is installed in a wetland, floodplain, river, lake or critical dune area, then a permit from DEQ-Land & Water Management Division will be required.(2) Contact Water Bureau staff at DEQ district office for permit application and requirements. (Rev 2/21/07)
YES
YES YES
YES
NO
NO
NO
NO
NO
YES
YES
NPDES DISCHARGE PERMIT IS NOT REQUIRED (1)
NO
Geothermal Heat Pump Systems Page 8 of 8
This document was produced by the Michigan Department of Environmental Quality (MDEQ) and is intended for guidance only. Reliance on information from this document is not usable as a defense in any enforcement action or litigation. The MDEQ will not discriminate against any individual or group on the basis of race, sex, religion, age, national origin, color, marital status, disability, or political beliefs. Questions or concerns should be directed to the Office of Human Resources, PO Box 30473, Lansing, MI 48909