Effectiveness of Retrofitting Ice Slurry Thermal Energy Storage for an Urban Hospital Chiller Plant

1. Effectiveness of Retrofitting
Ice Slurry Thermal Energy Storage
for an Urban Hospital Chiller Plant
Stan Rott
Marketing Director
IDE Technologies

2. Executive Summary
The main purpose of this study is to investigate the effectiveness
of the retrofitting of an ice slurry storage system for the existing
central chiller plant of a large size hospital.
The study is also focused on improvement of the hospital’s
chiller plant efficiency as well as reduction of the annual electric
cost by application of an ice slurry Thermal Energy Storage (TES)
system utilizing water vapor as the primary refrigerant.
The results are a nearly FLAT monthly Peak Demand curve, which
allows for a reduction of about 2,000 kW (~30%) compared to
the hospital’s current recorded Peak Demand data.

3. Objectives
Assess hospital’s current specific power consumption
Isolate base load not related to comfort cooling
Estimate existing chiller plant efficiency
Evaluate chiller plant power consumption after retrofitting
with ice slurry TES, based on one Vacuum Ice Maker (VIM)
with a rated capacity of 1,000 Tons
Compare current power consumption with the projected
power consumption after retrofit
Quantify monthly and annual electric savings resulting
from the retrofitting of the chiller plant with TES
Estimate the required scope of work

4. Existing Conditions
Hospital Chiller Plant
• 4 x 1,000 Tons
• 3 x 1,000 Tons by Trane, plus 1 x 1,000 Tons by York
• Chiller plant age: ~26 years
• Critical application areas: Clean rooms & Surgery
• 2 x 75 Tons
• 1 x 35 Tons
• Several 5 Ton units
• Chiller plant capacity: ~4,200 Tons
• Estimated specific power consumption: ~1.1 kW/Ton

5. VIM & TES Reservoir
Preliminary Site Survey
1. VIM will be installed on
the rooftop
2. Rooftop structure may
need to be reinforced
3. TES Tank has no
limitation in terms of
shape, form or materials
of construction
Hospital building crawl space
would be retrofitted as a TES
Retrofit Scope:
Tank with total approximate • Application of a waterproof liner
volume of 150,000 ft3 and • Buffer reservoir & associated piping
stored cooling capacity of
about 50,000 Ton-hours

6. Design Consideration
Storage Type
• Daily/Weekly
• Seasonal
Tariff Structure
• Peak Demand
charges
• Peak vs. Off-peak
billing periods
Control Strategy
• Peak Demand
reduction
• Peak Demand set
point control

7. Preliminary Data Analysis
Hospital’s Power Consumption Data: hourly meter reading
• October, 2009 to October, 2010
Highest Annual Electric Peak Demand
• July 6th: 6,054 kW

8. Preliminary Data Analysis
Annual Load Duration Curve
• October, 2009 to October, 2010
Hospital’s Load Analysis
• Base Electric Load: ~1,900 kW

9. Control Strategy
Tariff Structure
• Peak Demand Charges: 60% to 70%
• Time-of-Day Charges: minimal differences from peak to off-peak
From Date To Date Meter # kWhr Demand,kW Charge,$/kW Charge,$/kWhr Charge,$/mo From Date To Date Meter # kWhr Demand,kW Charge,$/kW Charge,$/kWhr Charge,$/mo
8/25/2010 9/24/2010 5656007 518,400 7/27/2010 8/25/2010 5656007 566,400
5656008 528,000 5656008 499,200
5656009 432,000 5656009 628,800
5656029 523,200 5656029 614,400
7031005 518,400 7031005 614,400
Total 2,520,000 5,768 Total 2,923,200 5,976
On Peak Energy Consumption 1,257,556 On Peak Energy Consumption 1,397,027
Off Peak Energy Consumption 1,262,444 Off Peak Energy Consumption 1,526,173
CHARGES CHARGES
Primary Distribution Demand 13.36 77,060.51 Primary Distribution Demand 12.91 77,178.09
Transmission Demand 7.14 41,183.52 Transmission Demand 6.90 41,246.35
On Peak Energy Consumption 0.02 18,980.78 On Peak Energy Consumption 0.0061 8,535.15
Off Peak Energy Consumption 0.0151 19,054.56 Off Peak Energy Consumption 0.0061 9,324.16
System Benefit Charge 0.0059 14,867.99 System Benefit Charge 0.0059 17,246.87
Temporary NYS Surcharge 0.0039 9,941.40 Temporary NYS Surcharge 0.0039 11,532.02
Billing & Payment Surcharge 1.04 Billing & Payment Surcharge 1.04
Total Meter Charge Total Meter Charge
Meter 37.56 Meter 36.31
Meter Reading 9.90 Meter Reading 9.57
Meter Maitenance 16.44 Meter Maitenance 15.89
Tax Charges 4,323.59 Tax Charges 3,941.06
TOTAL CHARGES 185,477.29 TOTAL CHARGES 169,066.51
Percent of Peak Demand 64% Percent of Peak Demand 70%

10. Control Strategy
Terminology Description
• Process: Hospital’s Electric Load
• Disturbance to the Process: Electric Load Fluctuations
• Measurement: Real Time Electric Power Consumption Metering
• Controller: Programmable Logic Controller (PLC)
• Set Point: Monthly Peak Demand Level
• Adjustment: Chilled Water Flow Rate

11. Control Strategy
Implementation
11:00 pm – 4:00 am 5:00 am – 8:00 pm TES Load: 1.0 kW/Ton
Process Disturbance
Measurement Set Point
TES Load

12. Design Targets
One Time Incentives offered through State Org. & Utilities
Program Participation: Curtailable Service
Category Program
Peak Demand Reduction: 80% NYSERDA: $600.00/kW
ConEd: $500.00/kW
Demand Response: 10% NYSERDA: $200.00/kW
NISO: CSP Participation
Emergency TES Ballast: 10% N/A

13. Results
Monthly Summary – March: TES Full Load Shift
Design Day Design Day w/ TES
Ice Slurry TES Charge/Discharge
Load Duration Curve LDC w/ TES
Monthly Target Peak Demand: 2,750 kW

14. Results
Monthly Summary – July: Highest Peak Demand 6,054 kW
Design Day Design Day w/ TES
Ice Slurry TES Charge/Discharge
Load Duration Curve LDC w/ TES
Monthly Target Peak Demand: 4,820 kW

15. Results
Annual LDC: Before & After TES Monthly Peaks: Before & After TES
Load Redistribution Peak Demand Reduction

16. Results
Key characteristics of Ice Slurry TES
• Independent TES Charge and Discharge Loops
• Simultaneous operation of TES Charge and Discharge loops
Highest Expected Discharge Rate

17. Results
Ice Slurry TES Operation Period: March through October
Peak Reduction Annuals Savings Summary*
Month Pre- kW Post- kW Reduction $/kW Savings $
Jan 3072 3072 0 - $0.00
Feb 3060 3060 0 - $0.00
Mar 3108 2750 358 $18.80 $6,730.40
Apr 4932 2812 2120 $19.00 $40,280.00
May 5580 3750 1830 $21.87 $40,022.10
Jun 5864 4500 1364 $19.81 $27,020.84
Jul 6054 4820 1234 $21.87 $26,987.58
Aug 5968 4450 1518 $19.81 $30,071.58
Sep 5748 4430 1318 $20.50 $27,019.00
Oct 4456 2650 1806 $20.50 $37,023.00
Nov 3138 3108 0 - $0.00
Dec 3066 3046 0 - $0.00
Total $235,154.50
Simple Payback Period: 6 years (or less in cases when adding or
upgrading chiller plant capacity)
* The $/kW are indicative of ConEd service territory

18. Scope of Supply
Retrofit Scope
• Vacuum Ice Maker – VIM850 (1,000 Tons)
• TES Reservoir Retrofit (hospital crawl space mod’s)
• Plate & Frame Heat Exchanger
• Circulation System (pumps, piping, valves, controls, etc.)
• Transportation to the Site
• VIM Installation
• VIM Maintenance Area
• Structural Reinforcements (for roof installations)

19. Conclusions
Accomplished Project Goals
Peak Demand Reduction
Demand Response
Improved Existing Chiller Plant Efficiency
Improved Existing Chiller Plant Reliability
Significant Annual Operating Energy Cost Savings
Can Earn Utility Incentives
Key Characteristics of VIM Ice Slurry TES
• Environmentally Friendly – Uses Water Vapor as the ONLY Refrigerant
• Low Energy Consumption – less than 1.0 kW/Ton for ice making
• RAPID and VARIABLE Discharge Capabilities, with COLD supply temps
• Produces a pumpable and non-coagulating ice slurry
• Uses a compact, simple, and low cost TES Tank

20. Contact Information
Stan Rott
Marketing Director
IDE Technologies
main: 1-516-734-0420
cell: 1-267-210-3396
shlomir@ide-tech.com
www.ide-tech.com