Transcript Design, Analysis & Cost Development Albert A. Koenig, Ph.D. ARB/Geowell Systems

Design, Analysis & Cost Development
of a 220 Ton Geothermal HVAC System
Albert A. Koenig, Ph.D.
ARB/Geowell Systems
www.ARBgeowell.com
Presentation Outline
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L.E.E.D. Building Design (Silver) Goals
Load Modeling/Simulation
HVAC Distribution Technology
Hydronic System Scheme
Site Information
Load Design Spec
The GeowellTM SCW Technology
GeowellTM String Deployment
220 Ton Geothermal Field Layout
Installed Cost & Payback
Building Design Standard
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Basis: ASHRAE/IESNA Standard 90.1-2004 for
building energy efficiency/sustainability and
Standard 62 for ventilation
Bldg. envelope & systems designed to maximize
energy performance, based on
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Computer simulation model (DOE-2, TRACE)
Identification & implementation of the most cost-effective
energy efficiency measures
Quantification of performance vs. baseline bldg.
20% renewable energy credit: geothermal
Building Operating Expense
Building Interior Daylighting
DOE-2: Model Bldg. Hourly Energy Use
Silver L.E.E.D. Design Goal
Targets:
 280 KBTU/sqf =>180 KBTU/sqf annual energy use
 HVAC equipment: 250 tons => 180 tons
Equipment:
 Innovative active chilled beam ceilings for integral
room comfort using geothermal chilled water to
provide 15°F ΔT (floor to ceiling)
 73% efficient economizer with energy recovery
wheel
Exposed Chilled Beam Technology
Esp. Suited for Open Office Areas
Chilled Beam Bldg. Heat Transfer
Chilled Beam Bldg. HX
emis=.65
20
15
10
Chilled Beam Bldg. HX
5
0
0
20
40
60
80
dT=15F
100
Heat Transfer (tons)
1
Emissivity
Flr-Clg dT(F)
25
0.8
0.6
0.4
0.2
0
30
40
50
60
Heat Transfer (tons)
70
80
Hydronic System Diagram
Building External HVAC Load: HDD/CDD
Bldg. Monthly Load
1200
MMBTU
1000
800
Heating
600
Cooling
400
200
0
1
2
3
4
5
6
7
8
9
10
11
12
Building HVAC Design Spec
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80,000 sqf office building (7 floors)
220 tons (365 sqf/ton)
Building Load:
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External Load: 92 tons
Internal Load: 128 tons
(lighting, people, equipment & air transport)
Site Information
20 acres wooded area (NJ/NY)
 Proximity to river for ground water recharge
 Ample water well records in vicinity
 Water 50-60’ from surface
 Excellent hydrogeology for geothermal
application
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Diffusivity (Sqf/day)
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Conductivity (BTU/hrftF)
Rock Thermal Properties
2.5
3
2
1.5
1
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0
2.0
1.5
1.0
0.5
0.0
Seasonal Heat Storage Measurement &
Modeling/Simulation @ 50’/ton
3.5
3
2.5
2
1.5
1
0.5
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0
10
20
30
40
50
60
70
Time (hr)
Avg. Formation Temperature
Over Thermal Penetration Distance
64
Rock Temp. (F)
Propagation L(ft)
Thermal Propagation in Wellbore
Continuous Heating
62
60
58
56
54
0
200
400
600
Time (hr)
800
1000
ARB/Geowell Technology
A New Old Approach for
Using Geothermal
Water Wells for Building
HVAC
Water Well Operation with Re-injection
Wellbore Heat Transfer
Patented in-Well String Design for Fast
Deployment & Maintenance
Impact of Polypipe Insulation
on Wellbore Heat Transfer
Wellbore Heat Transfer
HTC (BTUH/sqf F)
600
500
400
Colburn
300
Von Karman
200
ε/D = .01
100
0
0
0.1
0.2
0.3
0.4
0.5
Insulation Thickness (in)
0.6
Heat Transfer Benefit of GeowellTM:
4-Fold Improvement Over Closed Loops
Thermal Analysis: Closed Loop vs Geowell
Rock Prop: k=1.87BTUH/ftF, diff=1.11sqf/day
Resistance Ratio
(closed/geowell)
7
6
5
4
3
0
500
1000
1500
Op. Time (hr)
2000
2500
The ARB/Geowell Technology
Patented SCW technology that insure:
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minimal geofield installed expense
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use of deep (nom. 1000’) wells to minimize footprint and the number of
submersible pumps
the entire 6” wellbore diameter and length are utilized in return water
heat exchange
minimal total drilled length to satisfy bldg. load specification
fast installation of each well string
minimal field installation time (pre-fab ext. plumbing)
minimal operating expense
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minimal parasitic power utilization by employing a control algorithm
that activates on those well pumps that are needed to satisfy the load
well strings designed for ease of pump replacement
Fast In-Well Deployment
GeoWellTM Submersible Pump Housing
and Docking Assembly
GeoWellTM Injected Molded
Components
Geowell Advantages
Lower installed cost ($1300 vs. $2300 per ton)
Smaller wellfield footprint (20% of closed loop)
Minimal parasitics: well row operational selectivity
Wellfield design using minimal number of pumps
Pre-fab plumbing kits to min. field installation expense &
insure best practices
Fast installation of in-well components
Applications
220 Ton Geothermal
Field Layout
220 Ton Geowell Field Layout
220 Ton Design Specification
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Based on drilling to a nom. depth of 800’
20 water wells, operated 4 rows x 5 wells per
row, or 5 x 4
Well-well spacing 30’
Footprint: ⅓ acre
Installed cost: $211,800
Field Plumbing Schematic
Installed Cost Breakdown
GeoWell Field Cost Breakdown
Mech %
Civil/Install %
Electr %
Drilling %
Installed Cost & Payback
Geowell Example: 220 ton bldg. load
Installed loop (20 wells) price: $286,000
[Heat Pumps (220 tons total): $176,000]
less State Rebate ($/ton): ? - $ 77,000
less Fed Tax deduction:
- $ 48,000
Net Cost:
$161,000
Annual Operating Savings: $ 22,850
Discounted Payback: 6 yrs
Discounted Payback Analysis
NPV Analysis of Geothermal HVAC Applications
0.027 Fuel Escalation Rate
220
0.035 Cost of Living
12
0.05 Discount Rate
3
161000 Original Investment
20
86433.45 Annual Cost (NG/elect)
56832.8 Annual Cost (Geowell)
29600.65 Annual Savings
Year
0
1
2
3
4
5
6
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9
10
11
12
13
14
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16
17
18
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
Maintenance
Materials
1,011.31
1,046.71
1,083.34
2,242.51
2,321.00
3,603.35
3,729.47
2,573.34
2,663.40
1,378.31
1,426.55
Expense
Labor
$
$
281.52
$
291.37
$
301.57
$
312.13
$
323.05
$
334.36
$
346.06
$
716.34
$
741.42
$
767.37
$
1,191.34
$
1,233.03
$
1,701.58
$
1,761.14
$
1,367.08
$
1,414.93
$
976.30
$
1,010.47
ton
Calculation of Annual HVAC Load
mean value (yrs)
Heating mos.
stand. dev.
Cooling mos.
Number Pumps Electric Rate ($/kWh)
NG Rate ($/MMBTU)
Cash Flows
$
$
30,118.35
$
30,929.29
$
31,762.05
$
32,617.21
$
33,495.38
$
34,397.17
$
35,323.22
$
34,904.70
$
35,833.30
$
36,786.50
$
36,246.56
$
37,197.75
$
36,547.14
$
37,491.47
$
40,202.18
$
41,256.11
$
44,203.87
$
45,378.53
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
5
3
0.093
7.54
COP
SEER
avg. hr/mo. oper.
Failure Statistics
Cumulative NPV
Cumulative Failures
No. Failed in Period
0
0
28,684.14
0
0
56,737.92
0
0
84,175.17
0
0
111,009.43
0
0
137,253.94
0
0
162,921.64
0
0
188,025.19
1
1
211,650.07
2
1
234,748.53
3
1
257,332.25
5
2
278,524.87
7
2
299,237.96
10
3
318,619.69
13
3
337,555.43
15
2
356,893.37
17
2
375,793.27
18
1
395,079.27
19
1
413,934.98
20
1
Federal Tax Incentives
EPAct 2005 for Commercial Bldgs.
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Tax deduction of up to $1.80/sqf for
qualifying property (e.g.$144,000 for a
80,000 sqf bldg.)
Split three parts: ⅓ each for envelope,
lighting and HVAC
Fully qualifying property must show (in a
simulation) 50% energy & power savings
over a reference bldg. that meets minimum
Standard 90.1-2001
State Rebate Program
Geothermal GSHP Installations
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PA offers only Energy Harvest grant
opportunities and Sustainable Development
Fund (SDF) loan pool (7-9%) + PECO ($800
installation rebate)
NY: $150-800/ton under LIPA
NJ: $370/ton
DE: $600/ton capped at $25,000