the cost of using 1970’s era design concepts and “fear”in chilled water systems
DESCRIPTION
The Cost of Using 1970’s Era Design Concepts and “FEAR”in Chilled Water Systems. Presented By : Hemant Mehta, P.E. WM Group Engineers, P.C. What is the “FEAR”. No change in design as previous design had no complains from client No complain because no bench mark exists - PowerPoint PPT PresentationTRANSCRIPT
The Cost of Using 1970’s EraDesign Concepts and “FEAR”in
Chilled Water Systems
WMGroup Engineers, P.C.
Presented By: Hemant Mehta, P.E.
What is the “FEAR”
• No change in design as previous design had no complains from client– No complain because no bench mark exists– Fear to take the first step to change the concepts to
use state of the art technology– Consultants sell time. Fear is any new concept will
take lots of time and it is not worth the effort
What are1970’s EraDesign Concepts?
• System Design for Peak load only• Primary/Secondary/Tertiary Pumping• 5°C (42°F) supply temperature• System Balancing• Circuit Setters• Band Aid solution for any Problem• Projected Demand way above reality• Oversized chiller, pumps TDH and everything else to
cover behind
State of the Art Plant concepts
• Plant designed for optimum operation for the year. Peak hours are less than 200 hours a year
• Variable flow primary pumping system • 3.3°C (38°F) or lower supply temperature• No System Balancing. Balancing is for a static system.• No Delta P valves – No Circuit Setters• No Band Aid solution for any Problem• Use chilled water system diversity (0.63) to Project
Cooling Demand• The total Chilled water pumping TDH even for a very
large system should not be more 63 meters(than 200 feet)
Selecting Equipment to Optimize EfficiencyChiller equipment is often erroneously selected based on peak load efficiency.
Peak load only occurs for a small number of hours of the year, as shown on the load duration curve below:
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000
Load
(Ton
s)
Hours
Jeddah Airport - Cooling Load Duration Curve
The Design of the Human Body
Heart (Variable Volume Primary Pump)
Lungs(Chillers)
Brain (Building End-Users)
Basic 1970’s Era Chiller Plant Design
Primary Pump Secondary Pump
Decoupler Line
Building Loads
Chiller
Current Design Used on Many Large District Chilled Water Systems
Primary Pump
Secondary Pump
Decoupler Line
Building Loads
Chiller
EnergyTransferStation
Building Pump
Modern Variable Volume Primary Chiller Plant Design
Building Loads
Chiller
Variable Speed Primary Pump
Lost Chiller Capacity Due to Poor ΔT
5°C (41°F)
No Flow Through Decoupler
13°C (55.5°F)
5°C (41°F)
13°C (55.5°F)
150 L/sec (2,400 gpm)
150 L/sec (2,400 gpm)
150 L/sec (2,400 gpm)
150 L/sec (2,400 gpm)
Chiller sees a ΔT of 8°C (14.5°F) at a flow of 150 L/sec (2,400 gpm)
The chiller capacity is therefore 5,000 kW (1,450 tons)
Ideal Design Conditions
Lost Chiller Capacity Due to Poor ΔT
5°C (41°F)
9°C (48.25°F)
5°C (41°F)
13°C (55.5°F)
75 L/sec (1,200 gpm)
150 L/sec (2,400 gpm)
75 L/sec (1,200 gpm)
150 L/sec (2,400 gpm)
Chiller sees a ΔT of 4°C (7.25°F) at a flow of 150 L/sec (2,400 gpm)
The chiller capacity is therefore 2,500 kW (725 tons)
Case 1: Mixing Through Decoupler Line
75 L/sec (1,200 gpm)
at5°C (41°F)
Lost Chiller Capacity Due to Poor ΔT
5°C (41°F)
No Flow Through Decoupler
5°C (41°F)
150 L/sec (2,400 gpm)
150 L/sec (2,400 gpm)
150 L/sec (2,400 gpm)
150 L/sec (2,400 gpm)
Case 2: Poor Building Return Temperature
Chiller sees a ΔT of 4°C (7.25°F) at a flow of 150 L/sec (2,400 gpm)
The chiller capacity is therefore 2,500 kW (725 tons)
9°C (48.25°F) 9°C (48.25°F)
Small Loss in ΔT Rapidly ReducesChiller Capacity
System ΔT Chiller Capacity
8.0°C (14.4°F) 100%
7.5°C (13.5°F) 94%
7.0°C (12.6°F) 88%
6.5°C (11.7°F) 81%
6.0°C (10.8°F) 75%
5.5°C (9.9°F) 69%
5.0°C (9.0°F) 63%
4.5°C (8.1°F) 56%
4.0°C (7.2°F) 50%
Assuming a design ΔT of 8°C (14.4°F):
Technical Paper by Erwin Hanson(Pioneer in Chilled Water System Design)
8°C
9°C
11°C
Billing Algorithm for Buildings to Give Incentive to Owners to Improve ΔT
• Adjusted Demand Cost
• Adjusted Consumption Cost
• Total Cost = Demand + Consumption
Total Site Demand Cost
XBldg ton-hrsTotal ton-hrs
XCost
Penalty Factor
Total Site Electric Cost -
Total Adjusted Bldg Demand
CostX
Bldg ton-hrsTotal ton-hrs
The Design of the Human Body
Heart (Variable Volume Primary Pump)
Lungs(Chillers)
Brain (Building End-Users)
History of Variable Primary Flow Projects
• King Saud University - Riyadh (1977)• Louisville Medical Center (1984)• Yale University(1988)• Harvard University (1990)• MIT(1993)• Amgen (2001)• New York-Presbyterian Hospital (2002)• Pennsylvania State Capitol Complex (2005)• Duke University (2006)• NYU Medical Center (2007)• Memorial Sloan-Kettering Cancer Center (2007)
King Saud University – Riyadh (1977)• 60,000 ton capacity with 30,000 tons for first phase• Six 5,000 ton Carrier DA chillers• Seven 10,000 GPM 240 TDH constant speed pumps• Major Problem: Too much head on chilled water pumps• Lesson Learned: Be realistic in predicting growth
Louisville Medical Center (1984)
• Existing system (1984) – Primary/Secondary/Tertiary with 13,000 ton capacity
• Current System (2007)– 120 feet TDH constant speed primary pumps with
building booster pumps – 30,000 ton capacity– Changed the heads on some of the evaporator shells
to change number of passes– Primary pumps are turned OFF during winter, Early
Spring and Late Fall. Building booster pumps are operated to maintain flow.
Yale University (1988)• Existing system (1988)
– Primary/Secondary/Tertiary with 10,500 ton capacity• Current System (2007)
– 180 feet TDH VFD / Steam Turbine driven variable flow primary pumps – 25,000 ton capacity
– Changed the heads on some of the evaporator shells to change number of passes
Amgen (2001)• Creation of a computerized hydraulic model of the existing
chilled water plant and distribution system• Identification of bottlenecks in system flow• Evaluation of existing capacity for present and future loads• Two plants interconnected: Single plant operation for most
of the year, second plant used for peaking• Annual Energy Cost Savings: $500,000
Additional Variable Primary Flow Projects
• Harvard University (1990)• MIT(1993)• New York-Presbyterian Hospital (2002)• Pennsylvania State Capitol Complex (2005)• Duke University (2006)• NYU Medical Center (2007)• Memorial Sloan-Kettering Cancer Center (2007)
• CCWP-1 plant was built four years ago
• CCWP-2 design was 90% complete (Primary/Secondary pumping)
• We were retained by Duke to peer review the design
• Peer review was time sensitive
• Plant design for CCWP-2 was modified to Variable Primary pumping based on our recommendations
Duke University Background
Duke CCWP-1 Before
Duke CCWP-1 After• Dark blue pipe replaces old primary pumps
Duke CIEMAS Building CHW System
90% closed Triple duty valves50% closed
Balancing valve50% closed
Duke CIEMAS Building AHU-9
NYU Medical Center (2007)• Plant survey and hydraulic model indicated unnecessary pumps
• 1,300 horsepower of pumps are being removed, including 11 pumps in two brand new chiller plants
• $300,000 implementation cost
• $460,000 annual energy savings
NYU Medical Center (2007)• Plant survey and hydraulic model indicated unnecessary pumps
• 1,300 horsepower of pumps are being removed, including 11 pumps in two brand new chiller plants
• $300,000 implementation cost
• $460,000 annual energy savings
3 Pumps Removed
7 Pumps Removed
8 Pumps Removed
3 Pumps Removed
Memorial Sloan-Kettering - Before
Memorial Sloan-Kettering - After
Bypass or removal of pumps
Bypass or removal of pumps
Bypass or removal of pump
Pump Cemetery
To date we have removed several hundred large pumps from our clients’ chilled water systems
Plant Capacity Analysis -Detailed System Analysis is a Necessity
Modern computer software allows more complex modeling of system loads, which has proven to be very valuable to optimize performance and minimize cost.
Return on investment to the client for detailed analysis is typically very high.
• Applied revolutionary control logic
New York Presbyterian Hospital
Log Data ~ 20F T
Bristol-Myers Squibb• Biochemistry research building
• 140,000 square feet• AHU-1 (applied new control logic)
• 100,000CFM
• AHU-2 (existing control logic remained)• 100,000 CFM
Bristol-Myers Squibb• Applied revolutionary control logic
PA State Capitol Complex – CHW ΔT
South Nassau Hospital – CHW ΔT
Good Engineers Always Ask “Why?”
• Why does the industry keep installing Primary/Secondary systems?
• Why don’t we get the desired system ΔT?
• Why does the industry allow mixing of supply and return water?
Good Engineers Always Ask “Why?”
• Why does the industry keep installing Primary/Secondary systems?
• Why don’t we get the desired system ΔT?
• Why does the industry allow mixing of supply and return water?
Answer: To keep consultants like us busy!
Why change?
Reasons to Change
• The technology has changed
• Chiller manufacturing industry supports the concepts of Variable Primary Flow
• Evaporator flow can vary over a large range
• Precise controls provides high Delta T
Change is Starting Around the World• Most of the large district cooling plants in Dubai currently use
Primary/Secondary pumping
• By educating the client we were able to convince them that this is not necessary
• We are now currently designing three 40,000 ton chiller plants in Abu Dhabi using Variable Primary Flow as part of a $6.9 billion development project
Summary• There are many chilled water plants with significant
opportunities for improvement• WM Group has a proven record of providing smart solutions
that work• We will be happy to review your plant logs with no obligation
Louisville Medical Center Chilled Water Operating Data
0
5
10
15
20
25
30
35
40
45
50
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Year
CH
W P
rodu
ctio
n(m
illio
n to
n-ho
urs)
0.050
0.075
0.100
0.125
0.150
0.175
0.200
Cos
t($
/ton-
hour
)
Production Cost
1985: $ 0.171/ton-hr
2002: $0.096/ton-hr
September 16, 2008
The New Royal ProjectCentral Energy Plant Study
By
Determine the Optimum Central Energy Plant Configuration and Cogeneration Feasibility
Project Objective
• A new tertiary hospital for the region
• 95,000 m2 initial area (basis of analysis)
• Disaster Recovery Consideration• N+1• Onsite Power Generation (+/- 70% of peak demand)• Two separate central plants
The New Royal Project
Project Site
Typical Utility Tunnel
• Developing load profiles for Heating, Cooling and Power
• Developing and screening of Options
• Creating a computer model for energy cost estimate
• Performing Lifecycle Cost Analysis
• Performing Sensitivity Analysis
• Conclusions
Study Approach
• Cooling/Heating – Daily peaks provided by Bassett
• Cooling: 7,400 kWt (2,100 RT)• Heating: 8,000 kWt
• Power – Daily peaks provided by Bassett
• Peak demand: 4,500 kWe• Min. demand: 1,400 kWe
Load Profiles
Cooling Loads
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
Jan
Feb
Mar Ap
r
May Jun Jul
Aug
Sep
Oct
Nov Dec
Cool
ing
Load
(kW
t)Daily Peak Cooling Loads (Provided by Bassett)
Daily Cooling Load Profile1
2:0
0 A
M
1:0
0 A
M
2:0
0 A
M
3:0
0 A
M
4:0
0 A
M
5:0
0 A
M
6:0
0 A
M
7:0
0 A
M
8:0
0 A
M
9:0
0 A
M
10
:00
AM
11:0
0 A
M
12
:00
PM
1:0
0 P
M
2:0
0 P
M
3:0
0 P
M
4:0
0 P
M
5:0
0 P
M
6:0
0 P
M
7:0
0 P
M
8:0
0 P
M
9:0
0 P
M
10
:00
PM
11:0
0 P
M
NRP Average Daily Cooling Load Profile
Max Daily Cooling Load
Min Daily Cooling Load
3-D Cooling Load Profile
Cooling Load Duration Curve
0
500
1,000
1,500
2,000
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
5,500
6,000
6,500
7,000
7,500
8,000
0
50
0
1,0
00
1,5
00
2,0
00
2,5
00
3,0
00
3,5
00
4,0
00
4,5
00
5,0
00
5,5
00
6,0
00
6,5
00
7,0
00
7,5
00
8,0
00
8,5
00
Lo
ad (T
on
s)
Lo
ad (k
Wt)
Hours
NRP Cooling Load Duration Curve (kWt)
607 Equivalent Full-Load Hours
Heating Loads
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
Jan
Feb
Mar Ap
r
May Jun Jul
Aug
Sep
Oct
Nov Dec
Hea
ting
Load
(kW
t)Daily Peak Heating Loads (Provided by Bassett)
Daily Heating Load Profile1
2:0
0 A
M
1:0
0 A
M
2:0
0 A
M
3:0
0 A
M
4:0
0 A
M
5:0
0 A
M
6:0
0 A
M
7:0
0 A
M
8:0
0 A
M
9:0
0 A
M
10
:00
AM
11:0
0 A
M
12
:00
PM
1:0
0 P
M
2:0
0 P
M
3:0
0 P
M
4:0
0 P
M
5:0
0 P
M
6:0
0 P
M
7:0
0 P
M
8:0
0 P
M
9:0
0 P
M
10
:00
PM
11:0
0 P
M
NRP Average Daily Heating Load Profile
Max Daily Heating Load
Min Daily Heating Load
3-D Heating Load Profile
Heating Load Duration Curve
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
20,000
22,000
24,000
26,000
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
5,500
6,000
6,500
7,000
7,500
8,000
0
50
0
1,0
00
1,5
00
2,0
00
2,5
00
3,0
00
3,5
00
4,0
00
4,5
00
5,0
00
5,5
00
6,0
00
6,5
00
7,0
00
7,5
00
8,0
00
8,5
00
Lo
ad (M
BH
)
Lo
ad (k
Wt)
Hours
NRP Heating Load Duration Curve (kWt)
1,742 Equivalent Full-Load Hours
Electric Loads
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
Jan
Feb
Mar Ap
r
May Jun Jul
Aug
Sep
Oct
Nov Dec
Elec
tric
Loa
d (k
We)
Daily Peak Electric Loads (Provided by Bassett)
Daily Electrical Load Profile1
2:0
0 A
M
1:0
0 A
M
2:0
0 A
M
3:0
0 A
M
4:0
0 A
M
5:0
0 A
M
6:0
0 A
M
7:0
0 A
M
8:0
0 A
M
9:0
0 A
M
10
:00
AM
11:0
0 A
M
12
:00
PM
1:0
0 P
M
2:0
0 P
M
3:0
0 P
M
4:0
0 P
M
5:0
0 P
M
6:0
0 P
M
7:0
0 P
M
8:0
0 P
M
9:0
0 P
M
10
:00
PM
11:0
0 P
M
NRP Average Daily Electrical Load ProfileMax Daily
Electrical Load
Min Daily Electrical Load
3-D Electrical Load Profile
• Natural Gas: $9.00 / GJ
• Electricity (taken from hospital bill):• Demand Charge: $0.265641 per kVA per day
• Based on contracted annual demand• About $10.00 per kW per month
• Energy Charge:
• $0.14618 / kWh (on-peak, 7 am to 10 pm)• $0.05322 / kWh (off-peak, 10 pm to 7 am and
weekends)
• Fixed Charges: $27.7155 per day• About $830 per month
Utility Rates
• Minimum first cost
• Two locations
• Conventional equipment• Electric chillers
• Gas-fired boilers
• Diesel emergency generators
• No cogeneration or thermal storage
• Operational efficiency and reliability
Base Option Considerations
Central Energy Plant – Base Option
Plant Component
East CEP West CEP
Chiller Plant(2) 2,500 kWt electric motor driven, water-cooled chillers
(2) 2,500 kWt electric motor driven, water-cooled chillers
Boiler Plant(2) 2,750 kWt fire tube boilers producing hot water
(2) 2,750 kWt fire tube boilers producing hot water
Thermal Storage
None None
Power Generation
(1) 2,000 kVA diesel generator (emergency power)
(1) 2,000 kVA diesel generator (emergency power)
• Non-Electric Chillers• Absorption Chillers (with or without heaters)
• Steam Turbine Driven Chillers
• Gas Engine Driven Chillers
• Thermal Storage• Ice Storage
• Chilled Water Storage
• Cogeneration
• Geothermal
Alternative Plant Considerations
Electric vs. Non-Electric Chillers Sample taken from another project
Hybrid Plant – Option 1A Plant
ComponentEast CEP West CEP
Chiller Plant
(1) 2,650 kWt electric motor driven, water-cooled chiller(1) 2,450 kWt direct-fired absorption chiller/heater
(1) 2,650 kWt electric motor driven, water-cooled chiller(1) 2,450 kWt direct-fired absorption chiller/heater
Boiler Plant
(2) 1,750 kWt fire tube boilers producing hot water
(1) 1,500 kWt direct-fired absorption chiller/heater (same unit as above)
(2) 1,750 kWt fire tube boilers producing hot water
(1) 1,500 kWt direct-fired absorption chiller/heater (same unit as above)
Thermal Storage
None None
Power Generation
(1) 2,000 kVA diesel generator (emergency power)
(1) 2,000 kVA diesel generator (emergency power)
• Advantages of ice storage• Ice storage requires less space
• Suitable for low temperature operation
• Disadvantages of ice storage• Ice generation requires more energy
• Ice storage system has a higher first cost
• Ice storage is not considered for this project
Ice Storage vs. Chilled Water Storage
Thermal Storage – Option 2
Plant Component
East CEP West CEP
Chiller Plant(2) 1,750 kWt electric motor driven, water-cooled chillers
(2) 1,750 kWt electric motor driven, water-cooled chillers
Boiler Plant(2) 2,750 kWt fire tube boilers producing hot water
(2) 2,750 kWt fire tube boilers producing hot water
Thermal Storage
(1) 30,000 kWt-hr chilled water storage tank connected to site chilled water distribution system
Power Generation
(1) 2,000 kVA diesel generator (emergency power)
(1) 2,000 kVA diesel generator (emergency power)
Cogeneration AlternativesSystem Application Assessment
Reciprocating Engines Suitable for high electric but low thermal loads such as NRP.
Fuel Cells Emerging technology not for commercial use.
Microturbines Limited capacity of units and requires skilled labor.
High Pressure Steam Boiler and Back Pressure Turbine
No steam required by NRP.
High Pressure Steam Boiler and Condensing Turbine
No steam required by NRP.
Gas Turbine with HRSGTypically for larger installations, requires skilled operators, and possible emissions treatment issues.
Combined Cycle GenerationTypically for larger installations, requires skilled operators, and possible emissions treatment issues.
Engine Generator Topping Cycle
Option 3 – Cogen w/ Gas Engines
Plant Component
East CEP West CEP
Chiller Plant
(2) 1,750 kWt electric motor driven, water-cooled chillers(1) 1,140 kWt hot water-fired absorption chiller
(2) 1,750 kWt electric motor driven, water-cooled chillers(1) 1,140 kWt hot water-fired absorption chiller
Boiler Plant(2) 1,750 kWt fire tube boilers producing hot water
(2) 1,750 kWt fire tube boilers producing hot water
Thermal Storage
None None
Power Generation
(1) 2,000 kVA natural gas generator (cogeneration)
(1) 2,000 kVA diesel generator (emergency power)
(1) 2,000 kVA natural gas generator (cogeneration)
(1) 2,000 kVA diesel generator (emergency power)
* Diesel generators not required if onsite LNG storage is provided
Option 4 – Cogen & Thermal Storage
Plant Component
East CEP West CEP
Chiller Plant
(2) 1,750 kWt electric motor driven, water-cooled chillers(1) 1,140 kWt hot water-fired absorption chiller
(2) 1,750 kWt electric motor driven, water-cooled chillers(1) 1,140 kWt hot water-fired absorption chiller
Boiler Plant(2) 1,750 kWt fire tube boilers producing hot water
(2) 1,750 kWt fire tube boilers producing hot water
Thermal Storage
(1) 10,000 kWt-hr chilled water storage tank connected to site chilled water distribution system
Power Generation
(1) 2,000 kVA natural gas generator (cogeneration)
(1) 2,000 kVA diesel generator (emergency power)
(1) 2,000 kVA natural gas generator (cogeneration)
(1) 2,000 kVA diesel generator (emergency power)
* Diesel generators not required if onsite LNG storage is provided
Summary of OptionsOption Chiller Plant Boiler Plant Thermal Storage
Power Generation
1 (4) 2,500 kWt electric (4) 2,750 kWt boilers None(2) 2,000 kVA diesel backup generators
1A(2) 2,650 kWt electric,
(2) 2,450 kWt absorbers
(4) 1,750 kWt boilers, (2) 1,500 kWt absorbers
None(2) 2,000 kVA diesel backup generators
2 (4) 1,750 kWt electric (4) 2,750 kWt boilers(1) 30,000 kWt-hr chilled water storage
(2) 2,000 kVA diesel backup generators
3(4) 1,750 kWt electric,
(2) 1,140 kWt absorbers(4) 1,750 kWt boilers None
(2) 2,000 kVA natural gas cogen units,
(2) 2,000 kVA diesel backup generators
4(4) 1,750 kWt electric,
(2) 1,140 kWt absorbers(4) 1,750 kWt boilers
(1) 10,000 kWt-hr chilled water storage
(2) 2,000 kVA natural gas cogen units,
(2) 2,000 kVA diesel backup generators
• Simulation of plant operation
• Calculation of total energy use (power and fuel) and cost
Energy Model
Hourly Computer Model
Detailed Equipment Data
Monthly Energy Cost Summary
Monthly Energy Cost Graphs
Comparison of Annual Energy Costs
$3.7 M $3.7 M $3.6 M
$0.9 M $0.8 M
$0.6 M $0.6 M $0.6 M
$2.1 M $2.1 M
$0.0 M
$1.0 M
$2.0 M
$3.0 M
$4.0 M
$5.0 M
Option 1 Option 1A Option 2 Option 3 Option 4
Comparison of Annual Energy Costs
Electric Cost Gas Cost
$4.3 M $4.3 M $4.2 M
$3.0 M $3.0 M
Thermal Storage Economics
• Installed Cost (Opt. 1A):$1,700,000
• Annual Energy Savings: $98,000
• Simple Payback: 17 years
Low cooling load reduces benefits of thermal storage
25-Year Lifecycle Cost Analysis
• Capital Cost
• Energy Cost (gas and electric)
• Maintenance and Consumables Cost
• Staffing Cost
• Economic Rates
• Discount Rate
Construction Cost Estimates
Project Cost FactorsBased on typical healthcare development projects
• Preliminaries and Margin: 23%
• Project Contingency: 15%
• Cost Escalation to Start Date: 15%
• Consultant Fees: 10%
Total multiplier is approximately 1.8
Comparison of Initial Costs
$20.8 M$22.9 M $23.6 M
$28.0 M$29.5 M
$4.2 M$4.2 M
$ M
$5 M
$10 M
$15 M
$20 M
$25 M
$30 M
$35 M
$40 M
Option 1 Option 1A Option 2 Option 3 Option 4
Comparison of Initial Costs
Incremental Cost for Diesel Generators
Maintenance and Staffing Costs
Option Annual Maintenance Cost Annual Staffing Cost
1 $84,000 $130,000
1A $90,000 $130,000
2 $86,000 $130,000
3 $105,000 $195,000
4 $107,000 $195,000
• Options 3 and 4 also require a $240,000 engine overhaul every 5 years (included in analysis)
• Staffing cost based on $65,000 per year for each full-time staff employee
Economic ParametersBased on estimated government rates
• Discount Rate: 8.00%
• Gas Cost Escalation Rate: 4.30%
• Electric Cost Escalation Rate: 3.40%
• Maintenance Escalation Rate: 4.00%
• Consumables Escalation Rate: 4.00%
25-Year Lifecycle Cost Analysis
Cost SummaryOption First Cost
Annual Energy Cost
25-Year Present Worth Cost
1 $20,839,000 $4,345,000 $87,223,000
1A $22,879,000 $4,311,000 $88,825,000
2 $23,558,000 $4,243,000 $88,473,000
3 $32,176,000 $2,988,000 $83,303,000
4 $33,704,000 $2,978,000 $84,722,000
Results of Lifecycle Cost Analysis
$87 M
$89 M$88 M
$83 M
$85 M
$80 M
$81 M
$82 M
$83 M
$84 M
$85 M
$86 M
$87 M
$88 M
$89 M
$90 M
Option 1 Option 1A Option 2 Option 3 Option 4
Comparison of Present Worth Costs
Sensitivity Analysis
• Varying electric demand charge
• Varying gas cost
• Change economic parameters
• Carbon emission tax
• Use of geothermal energy
