Effectiveness of Retrofitting

Ice Slurry Thermal Energy Storage

for an Urban Hospital Chiller Plant

Stan RottMarketing DirectorIDE Technologies

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.

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

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

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

Tank with total approximate

volume of 150,000 ft3 and

stored cooling capacity of

about 50,000 Ton-hours

Retrofit Scope:

• Application of a waterproof liner

• Buffer reservoir & associated piping

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

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

Preliminary Data Analysis� Annual Load Duration Curve

• October, 2009 to October, 2010

� Hospital’s Load Analysis

• Base Electric Load: ~1,900 kW

Control Strategy� Tariff Structure

• Peak Demand Charges: 60% to 70%

• Time-of-Day Charges: minimal differences from peak to off-peakFrom Date To Date Meter # kWhr Demand,kW Charge,$/kW Charge,$/kWhr Charge,$/mo

8/25/2010 9/24/2010 5656007 518,400

5656008 528,000

5656009 432,000

5656029 523,200

7031005 518,400

Total 2,520,000 5,768

1,257,556

1,262,444

13.36 77,060.51

7.14 41,183.52

0.02 18,980.78

0.0151 19,054.56

0.0059 14,867.99

0.0039 9,941.40

1.04

37.56

9.90

16.44

4,323.59

185,477.29

64%

On Peak Energy Consumption

Off Peak Energy Consumption

CHARGES

Primary Distribution Demand

Transmission Demand

On Peak Energy Consumption

Off Peak Energy Consumption

System Benefit Charge

Tax Charges

TOTAL CHARGES

Temporary NYS Surcharge

Billing & Payment Surcharge

Total Meter Charge

Meter Reading

Meter Maitenance

Meter

Percent of Peak Demand

From Date To Date Meter # kWhr Demand,kW Charge,$/kW Charge,$/kWhr Charge,$/mo

7/27/2010 8/25/2010 5656007 566,400

5656008 499,200

5656009 628,800

5656029 614,400

7031005 614,400

Total 2,923,200 5,976

1,397,027

1,526,173

12.91 77,178.09

6.90 41,246.35

0.0061 8,535.15

0.0061 9,324.16

0.0059 17,246.87

0.0039 11,532.02

1.04

36.31

9.57

15.89

3,941.06

169,066.51

70%

On Peak Energy Consumption

Off Peak Energy Consumption

CHARGES

Primary Distribution Demand

Transmission Demand

On Peak Energy Consumption

Off Peak Energy Consumption

System Benefit Charge

Temporary NYS Surcharge

Billing & Payment Surcharge

Total Meter Charge

Meter

Meter Reading

Meter Maitenance

Tax Charges

TOTAL CHARGES

Percent of Peak Demand

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

Control Strategy� Implementation

11:00 pm – 4:00 am 5:00 am – 8:00 pm TES Load: 1.0 kW/Ton

∆

Disturbance

Set Point

TES Load

Process

Measurement

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

ResultsMonthly Summary – March: TES Full Load Shift

Load Duration Curve LDC w/ TES

Design Day Design Day w/ TES

Ice Slurry TES Charge/Discharge

Monthly Target Peak Demand: 2,750 kW

ResultsMonthly Summary – July: Highest Peak Demand 6,054 kW

Monthly Target Peak Demand: 4,820 kW

Design Day Design Day w/ TES

Ice Slurry TES Charge/Discharge

Load Duration Curve LDC w/ TES

Results

Annual LDC: Before & After TES Monthly Peaks: Before & After TES

Load Redistribution Peak Demand Reduction

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

ResultsIce Slurry TES Operation Period: March through October

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

Annuals Savings Summary*Peak Reduction

* The $/kW are indicative of ConEd service territory

Simple Payback Period: 6 years (or less in cases when adding or

upgrading chiller plant capacity)

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)

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

Contact InformationStan Rott

Marketing Director

IDE Technologies

main: 1-516-734-0420

cell: 1-267-210-3396

shlomir@ide-tech.com

www.ide-tech.com