design, analysis & cost development of a 220 ton geothermal hvac system
DESCRIPTION
Design, Analysis & Cost Development of a 220 Ton Geothermal HVAC System. Albert A. Koenig, Ph.D. ARB/Geowell Systems www.ARBgeowell.com. Presentation Outline. L.E.E.D. Building Design (Silver) Goals Load Modeling/Simulation HVAC Distribution Technology Hydronic System Scheme - PowerPoint PPT PresentationTRANSCRIPT
Design, Analysis & Cost Development of a 220 Ton Geothermal HVAC System
Albert A. Koenig, Ph.D.
ARB/Geowell Systems
www.ARBgeowell.com
Presentation Outline
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
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
– 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 tonsEquipment: 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 TechnologyEsp. Suited for Open Office Areas
Chilled Beam Bldg. Heat Transfer
Chilled Beam Bldg. HX
0
5
10
15
20
25
0 20 40 60 80 100
Heat Transfer (tons)
Flr
-Clg
dT
(F)
emis=.65
Chilled Beam Bldg. HX
0
0.2
0.4
0.6
0.8
1
30 40 50 60 70 80
Heat Transfer (tons)
Em
iss
ivit
y
dT=15F
Hydronic System Diagram
Building External HVAC Load: HDD/CDD
Bldg. Monthly Load
0
200
400
600
800
1000
1200
1 2 3 4 5 6 7 8 9 10 11 12
MM
BT
U
Heating
Cooling
Building HVAC Design Spec
80,000 sqf office building (7 floors) 220 tons (365 sqf/ton) Building Load:
– 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
Rock Thermal Properties
0
0.5
1
1.5
2
2.5
3
Co
nd
ucti
vit
y (
BT
U/h
rftF
)
0.0
0.5
1.0
1.5
2.0
Dif
fusiv
ity (
Sq
f/d
ay)
Seasonal Heat Storage Measurement & Modeling/Simulation @ 50’/ton
Thermal Propagation in WellboreContinuous Heating
00.5
11.5
22.5
33.5
0 10 20 30 40 50 60 70
Time (hr)
Pro
pa
ga
tio
n L
(ft)
Avg. Formation TemperatureOver Thermal Penetration Distance
54
56
58
60
62
64
0 200 400 600 800 1000
Time (hr)
Ro
ck
Te
mp
. (F
)
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
0
100
200
300
400
500
600
0 0.1 0.2 0.3 0.4 0.5 0.6
Insulation Thickness (in)
HT
C (
BT
UH
/sq
f F
)
Colburn
Von Karman
ε/D = .01
Heat Transfer Benefit of GeowellTM: 4-Fold Improvement Over Closed Loops
Thermal Analysis: Closed Loop vs GeowellRock Prop: k=1.87BTUH/ftF, diff=1.11sqf/day
3
4
5
6
7
0 500 1000 1500 2000 2500
Op. Time (hr)
Re
sis
tan
ce
Ra
tio
(clo
se
d/g
eo
we
ll)
The ARB/Geowell Technology
Patented SCW technology that insure: minimal geofield installed expense
• 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• 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
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
Geowell Advantages
Applications
220 Ton Geothermal Field Layout
220 Ton Geowell Field Layout
220 Ton Design Specification
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
Drilling %
Electr %
Civil/Install %
Mech %
Installed Cost & Payback
Geowell Example: 220 ton bldg. loadInstalled loop (20 wells) price: $286,000[Heat Pumps (220 tons total): $176,000]less State Rebate ($/ton): ? - $ 77,000less Fed Tax deduction: - $ 48,000Net Cost: $161,000Annual Operating Savings: $ 22,850Discounted Payback: 6 yrs
Discounted Payback Analysis
NPV Analysis of Geothermal HVAC Applications0.027 Fuel Escalation Rate 220 ton Calculation of Annual HVAC Load0.035 Cost of Living 12 mean value (yrs) Heating mos. 5 COP0.05 Discount Rate 3 stand. dev. Cooling mos. 3 SEER
161000 Original Investment 20 Number Pumps Electric Rate ($/kWh) 0.093 avg. hr/mo. oper.86433.45 Annual Cost (NG/elect) NG Rate ($/MMBTU) 7.5456832.8 Annual Cost (Geowell)
29600.65 Annual Savings
Maintenance Expense Failure StatisticsYear Materials Labor Cash Flows Cumulative NPV Cumulative Failures No. Failed in Period
0 -$ -$ -$ -$ 0 01 -$ 281.52$ 30,118.35$ 28,684.14$ 0 02 -$ 291.37$ 30,929.29$ 56,737.92$ 0 03 -$ 301.57$ 31,762.05$ 84,175.17$ 0 04 -$ 312.13$ 32,617.21$ 111,009.43$ 0 05 -$ 323.05$ 33,495.38$ 137,253.94$ 0 06 -$ 334.36$ 34,397.17$ 162,921.64$ 0 07 -$ 346.06$ 35,323.22$ 188,025.19$ 1 18 1,011.31$ 716.34$ 34,904.70$ 211,650.07$ 2 19 1,046.71$ 741.42$ 35,833.30$ 234,748.53$ 3 1
10 1,083.34$ 767.37$ 36,786.50$ 257,332.25$ 5 211 2,242.51$ 1,191.34$ 36,246.56$ 278,524.87$ 7 212 2,321.00$ 1,233.03$ 37,197.75$ 299,237.96$ 10 313 3,603.35$ 1,701.58$ 36,547.14$ 318,619.69$ 13 314 3,729.47$ 1,761.14$ 37,491.47$ 337,555.43$ 15 215 2,573.34$ 1,367.08$ 40,202.18$ 356,893.37$ 17 216 2,663.40$ 1,414.93$ 41,256.11$ 375,793.27$ 18 117 1,378.31$ 976.30$ 44,203.87$ 395,079.27$ 19 118 1,426.55$ 1,010.47$ 45,378.53$ 413,934.98$ 20 1
Federal Tax IncentivesEPAct 2005 for Commercial Bldgs.
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 ProgramGeothermal GSHP Installations
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