‘Alternative Farming Center’, Johnson County, Tennessee
Andrew
Andrew
Chiasson
Chiasson
Geo
Geo
-
-
Heat Center
Heat Center
Oregon Institute of Technology
Oregon Institute of Technology
Geothermal Heat Pumps
Geothermal Heat Pumps
in Agricultural Applications
in Agricultural Applications
Oregon
Oregon
Geothermal
Geothermal
Working
Working
Group Meeting
Group Meeting
May 17, 2006
Presentation Outline
Presentation Outline
•
•
Overview of geothermal heat pump
Overview of geothermal heat pump
(GHP) systems
(GHP) systems
aka: GeoExchange (GX), ground-source,
ground-coupled
•
•
Feasibility of agricultural applications
Feasibility of agricultural applications
Greenhouses
Aquaculture
Dairy farming
•
•
Example agricultural installations
Example agricultural installations
Detroit, MI
•
•
Heating
Heating
•
•
Cooling
Cooling
•
•
Hot water
Hot water
•
•
Humidity control
Humidity control
•
•
Ice making
Ice making
Overview:
Overview:
What do GHP systems provide?
What do GHP systems provide?
No outdoor equipment (no noise
or outdoor maintenance)
Comfort & air quality
Reduced peak electrical loads for
air conditioning
Residential Heat Pump
…but also…
Energy efficiency
Decreased maintenance
Decreased space needs
Low operating costs
1.
1.
Earth connection
Earth connection
Closed-loop
Open-loop
2.
2.
Water
Water
-
-
source heat pump
source heat pump
3.
3.
Interior heating/ cooling
Interior heating/ cooling
distribution subsystem
distribution subsystem
Forced air
Radiant
Components of GHP Systems
Components of GHP Systems
1
1
2
2
3
3
Components:
Components:
Water
Water
-
-
Source Heat Pump
Source Heat Pump
•
•
Water
Water
-
-
to
to
-
-
air or
air or
water
water
-
-
water heat
water heat
pump
pump
•
•
¾
¾
to 10 ton units
to 10 ton units
are most common
Vertical Closed
Vertical Closed
-
-
Loop
Loop
Horizontal Closed
Horizontal Closed
-
-
Loop
Loop
Spiral slinky,
Trenching
Excavation for a horizontal
Open
•
•
Closed
Closed
-
-
loop lengths depend on:
loop lengths depend on:
Peak hourly load
Annual heating loads vs. annual cooling loads
Optimum loop lengths occur when annual loads are balanced
•
•
Open
Open
-
-
loops:
loops:
Required groundwater flow rate depends on its temperature
(usually about 2 gpm/ton)
Groundwater quality and regulations!!
Some GHP Design Considerations:
Some GHP Design Considerations:
Loop Sizing
Some GHP Design Considerations:
Some GHP Design Considerations:
Peak vs. Annual Loads
Peak vs. Annual Loads
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
% of Peak Load Installed as Geothermal
%
of
Tot
a
l A
n
nua
l Loa
d
H
a
ndle
d
GHPs
GHPs
and Greenhouses:
and Greenhouses:
Feasibility
Feasibility
$4 $5 $6 $7 $8 $9 $10 $11 $12
Closed Loop Installation Cost ($/ft of vertical bore) Closed Loop Installation Cost ($/m of vertical bore)
$0.50 $0.75 $1.00 $1.25 $1.50 $1.75 $2.00 Natu ral Gas C o st ($ /th e rm) I N F E A S I B L E R E G I O N Region where geoth ermal c ould ha ndle <15% of the total a nnual l oad Regio n whe re ge otherm al co uld ha ndle 15-30 % of the to tal an nual load Regio n wh ere ge othe rmal could han dle 30-5 0% o f the tota l ann ual lo ad Regio n wh ere ge othe rmal could han dle 50-7 0% o f the tota l ann ual lo ad $15 $20 $25 $30 $35 $40 $2 $3 $4 $5 $6 $7 $8 $9 $10
Open Loop Installation Cost ($100/ton) Open Loop Installation Cost ($100/kW)
Nat u ral G a s C o st ($/m^ 3 )
Region where geothermal could handle up to 30% of the total annual load
$1.0 $1.5 $2.0 $2.5 $0.20 $0.30 $0.40 $0.50 $0.60 $0.70
Region where geothermal could handle 30-50%
of the total annual load
Region where g eotherm al could handle 50-70% of the t otal ann ual load Region where g eotherm al could handle 70-80% of the t otal ann ual load Region where geotherm al coul d hand le 80-90% of the total a nnual lo ad R e g i o n w h e r e g e o t h e r m a l c o u l d h a n d l e >9 0 % o f t h e t o t a l a n n u a l l o a d
Contours represent fraction of geothermal capacity to the peak hourly heating load
Full article available at http://geoheat.oit.edu/bulletin/bull26-1/art2.pdfGHPs
GHPs
and Aquaculture:
and Aquaculture:
Feasibility
Feasibility
$4 $5 $6 $7 $8 $9 $10 $11 $12
Closed Loop Installation Cost ($/ft of vertical bore) Closed Loop Installation Cost ($/m of vertical bore)
$0.50 $0.75 $1.00 $1.25 $1.50 $1.75 $2.00 Natu ral Gas Cost ($ /th e rm) I N F E A S I B L E R E G I O N Region where geothermal could
handle <15% of total a nnual load
Region where geothe
rmal could han
dle 15-30% of total a nnual load Region where geo
thermal could han
dle 30-55% of tota l annual load Regio n where geoth ermal c ould h andle 5 5-80% of tota l annua l load R e g i o n w h e r e g e o t h e r m a l c o u l d h a n d l e > 8 0 % o f t o t a l a n n u a l l o a d $15 $20 $25 $30 $35 $40 $2 $3 $4 $5 $6 $7 $8 $9 $10
Open Loop Installation Cost ($100/ton) Open Loop Installation Cost ($100/kW)
Nat u ral Gas C o st ($ /m^ 3)
Region where geothermal could handle up to 30% of the total annual load Region where geothermal could handle 30-55% of the total annual load Region where geothermal could handle 5
5-80% of the total annual load Region where geothermal could handle 80-90% of the total a
nnual load R e g i o n w h e r e g e o t h e r m a l c o u l d h a n d l e > 9 0 % o f t o t a l a n n u a l l o a d $1.0 $1.5 $2.0 $2.5 $0.20 $0.30 $0.40 $0.50 $0.60 $0.70
Contours represent fraction of geothermal capacity to the peak hourly heating load
Full article available at http://geoheat.oit.edu/bulletin/bull26-1/art3.pdfGHPs
GHPs
Applied to a Dairy Farm
Applied to a Dairy Farm
GEOTHERMAL LOOP
CLOSED-LOOP EARTH HEAT EXCHANGERS IN VERTICAL BOREHOLE ARRAY (single U-tube type, high-density
polyethylene) CIRCULATING
PUMP WATER-TO-WATER
HEAT PUMP HEATING & COOLING
WATER COIL STORAGE TANK LOAD 1 SPACE HEATING & COOLING LOAD 2 HOT WATER GENERATION (for dairy process) LOAD 3 MILK
CHILLING PROCESS DESCRIPTION
THE GEOTHERMAL LOOP ACTS AS A HEAT SOURCE AND SINK FOR WATER-SOURCE HEAT PUMPS.
IN ADDITION, THE GEOTHERMAL LOOP WILL ACT AS A THERMAL STORAGE MEDIUM, ALLOWING LOADS 2 AND 3 TO COMPLEMENT EACH OTHER ON BOTH SHORT AND LONG TIME SCALES. FOR EXAMPLE, LOAD 2 (HOT WATER
GENERATION) WILL ONLY EXTRACT HEAT FROM THE LOOP WHILE LOAD 3 WILL ONLY REJECT HEAT TO THE LOOP. WHEN THESE TWO LOADS ARE IN DEMAND SIMULTANEOUSLY, THE NET LOAD ON THE EARTH LOOP APPROACHES ZERO. AT OTHER TIMES, THERMAL ENERGY WILL BE TRANSFERRED TO/FROM THE EARTH BY ONE LOAD AT CERTAIN TIMES, AND THEN RECOVERED BY THE OTHER LOAD AT LATER TIMES.
GEOTHERMAL LOOP
CLOSED-LOOP EARTH HEAT EXCHANGERS IN VERTICAL BOREHOLE ARRAY (single U-tube type, high-density
polyethylene) CIRCULATING
PUMP WATER-TO-WATER
HEAT PUMP HEATING & COOLING
WATER COIL STORAGE TANK LOAD 1 SPACE HEATING & COOLING LOAD 2 HOT WATER GENERATION (for dairy process) LOAD 3 MILK
CHILLING PROCESS DESCRIPTION
THE GEOTHERMAL LOOP ACTS AS A HEAT SOURCE AND SINK FOR WATER-SOURCE HEAT PUMPS.
IN ADDITION, THE GEOTHERMAL LOOP WILL ACT AS A THERMAL STORAGE MEDIUM, ALLOWING LOADS 2 AND 3 TO COMPLEMENT EACH OTHER ON BOTH SHORT AND LONG TIME SCALES. FOR EXAMPLE, LOAD 2 (HOT WATER
GENERATION) WILL ONLY EXTRACT HEAT FROM THE LOOP WHILE LOAD 3 WILL ONLY REJECT HEAT TO THE LOOP. WHEN THESE TWO LOADS ARE IN DEMAND SIMULTANEOUSLY, THE NET LOAD ON THE EARTH LOOP APPROACHES ZERO. AT OTHER TIMES, THERMAL ENERGY WILL BE TRANSFERRED TO/FROM THE EARTH BY ONE LOAD AT CERTAIN TIMES, AND THEN RECOVERED BY THE OTHER LOAD AT LATER TIMES.
