TRIGENERATION STUDY TO INVESTIGATE THE FEASIBILITY OF PROCURING FREE COOLING FROM THE

WASTE HEAT PRESENTLY REJECTED FROM AN EXISTING CHP INSTALLATION.

EPSILON CONSULTANTS (IOM) LIMITED

7 Heather Lane | Douglas| Isle of Man.

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AUTHOR

MICHAEL GLANFIELD CEng MEI MIET MSLL

Epsilon Consultants (IOM) Limited

Registered address: 7 Heather lane

Abbeyfields Douglas

Isle of Man IM2 7EF

Contact details:

Tel: 01624 677278 Mobile: 07624 346826 Email: info@epsiloniom.com Web: www.epsiloniom.com

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CONTENTS

1.0 INTRODUCTION 2.0 EXECUTIVE SUMMARY 3.0 BASIS OF CLIENT BRIEF

4.0 PREVIOUS REPORTS 5.0 DESCRIPTION OF EXISTING INSTALLATION

5.1 Heating Systems

5.2 Cooling Systems

5.3 CHP Installation

6.0 ANALYSIS AND DISCUSSION

6.1 Existing CHP Performance

6.2 Electrical Consumption Data (MSB1)

6.3 Electrical Consumption Data (MSB2)

6.4 Additional CHP Installation (Option ‘A’)

6.4.1 Additional CHP Estimated Savings (Option ‘A’)

6.4.2 Additional CHP Simple Payback (Option ‘A’)

6.5 Additional CHP installation (Option ‘B’)

6.5.1 Additional CHP Estimated Savings (Option ‘B’)

6.5.2 Additional CHP Simple Payback (Option ‘B’)

6.6 Heat Demand versus External Temperature Data

6.7 Gas Consumption Data

6.8 CHP Waste Heat vs Cooling Capacity

6.9 Adsorption or Absorption Chiller

6.10 Simple Payback Period

6.10.1 Adsorption Chiller Simple Payback (Option ‘A’)

6.10.2 Absorption Chiller Simple Payback (Option ‘B’)

6.11 Adiabatic cooling

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APPENDICIES

CHARTS

i. Half-hourly Electrical Demand Charts

ii. Daily Electrical Demand Charts

iii. Monthly Electrical Demand Charts

iv. Existing CHP Electrical Performance Charts

v. Draft Electrical Load Assessment

vi. Daily Gas Demand Charts

vii. Monthly Gas Demand Chart

viii. Existing CHP Waste Heat Charts (water flow)

ix. Existing CHP Waste Heat Charts (flow & return temperatures)

x. Existing CHP Waste Heat Charts (kwh)

SUPPLIERS & MISCELLANEOUS

xi. Adsorption Chiller details - Weatherite Ltd.

xii. Absorption Chiller details – Toshiba Carrier UK Ltd.

xiii. Water Cooling details – Carter Environmental Engineers Ltd.

xiv. Adiabatic Dry Cooler details – Transtherm Ltd.

xv. Additional CHP - ENER-G Combined Power Ltd.

xvi. Cogeneration & On-Site Power Production article

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1.0 INTRODUCTION Epsilon Consultants were engaged by #### to investigate and report on the potential for upgrading the existing co-generation CHP (Combined Heat and Power) plant to achieve tri-generation capability. Reports ref: #### and #### should be read in conjunction with this supplementary report.

2.0 EXECUTIVE SUMMARY

a. The existing CHP system is playing an important role in providing a low energy solution to meet the needs of the site.

b. The existing CHP appears to possess spare electrical capacity which is not presently being

harnessed to reduce the electrical operating costs of the site and is recommended to be investigated further.

c. Any additional electrical capacity harnessed from the existing CHP shall also be reflected by

a consequent increase in the quantity of waste heat generated.

d. An additional CHP gas engine dedicated to meet the electrical demands of MSB2 would further reduce the costs of purchasing electricity for the site.

e. Waste heat liberated by the additional CHP engine may be harnessed to displace a quantity

of natural gas that is purchased to provide LTHW heating and hot water for the site.

f. The cooling capacity of the property may be increased in the summer months by the introduction of an adsorption or absorption chiller with the primary energy being derived from the CHP waste heat presently liberated by the heat rejection equipment during the summer period.

g. For environmental reasons Epsilon Consultants (IOM) Ltd recommend the selection of an

adsorption chiller design incorporating a naturally occurring and benign dry desiccant such as zeolite or silica gel.

h. Ongoing data logging of the CHP waste heat supply & return temperatures are

recommended to be carried out in order to assist with the optimum final selection of adsorption chiller.

i. For reasons of sound design and the elimination of the risk of legionnaire’s disease Epsilon Consultants (IOM) ltd recommend the selection of a ‘spray-less’ adiabatic design of water cooler (forming part of the adsorption chiller installation).

3.0 BASIS OF CLIENT BRIEF

The remit given to Epsilon Consultants was to investigate and report on the possibility of utilising the waste heat being discharged from the CHP’s heat rejection coil or ‘heat dump’ to provide additional cooling capacity.

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4.0 PREVIOUS REPORTS

The previous reports made a number of recommendations concerning the apparent lack of performance from heat station ‘3’ and for the recommissioning of the heating distribution system once the remedial works to heat station ‘3’ have been carried out. The client has recently brought to our attention the following matters which might influence the results of the original study and has requested a supplementary report to be prepared:

a. Remedial works to Heat Station ‘3’ have been carried out and completed. b. Technical issues concerning the metering of the main gas supply have been identified

and addressed. c. Daily data records of gas, electricity and CHP demands are now available for analysis.

5.0 DESCRIPTION OF EXISTING INSTALLATIONS

The original Mechanical, Electrical and Public Health systems were designed by #### consulting engineers, and installed by #### under sub-contract to #### who were the main Contractors for the site. The main plant area is located to the rear of the East wing and accommodates all the necessary plant and equipment required to provide all the services needs of the building, it is referred to as ‘The Energy Centre’. 5.1 Heating Systems The heating plant consists of three dual fuel gas fired (Natural Gas)/oil fired Robey Cochrane boilers, these are configured as follows;

Boiler 1 2.8Mw (2,800Kw) Boiler 2 2.8Mw (2,800Kw) Boiler 3 1.8Mw (1,800Kw)

Total 7.4Mw (7,400Kw)

Dependant on the fluctuations of the utilities at the time the heating plant can be switched between fuels to obtain the best value for money available at a given time. Generally the heating load is distributed via three heat stations at high temperature. These heat stations then distribute heating for both thermal comfort and domestic hot water from secondary heat exchangers to ceiling mounted radiant heating panels, air handling unit heating coils and domestic hot water systems.

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5.2 Cooling Systems The existing cooling system consists of two roof mounted mechanical chillers, these are located on the flat roof area above the production kitchen. The chillers are manufactured by ‘Powermaster’ model FE/STRAT/LN 1603 and are rated at 423Kw each, giving a total cooling capacity of 846Kw. During construction structural provision was made for the installation of a third chiller unit. The chillers are charged electrically from a 3 phase/415v supply, the chillers are energised overnight to take advantage of the reduced rate tariff and provides chilled water to two ice storage vessels located in the energy centre, each vessel is 43 m³ in volume giving a total storage volume of 86 m³. The secondary chilled water is designed to achieve a flow and return temperature of 6°c and 12°c respectively. The chilled water circuit from the ice storage vessels serve a primary plate heat exchanger, which in turn serves the entire site. This heat exchanger is manufactured by Alfa Laval and is rated at 1603Kw 5.3 Existing CHP installation

The existing CHP Unit is a ‘Guascor’ model SFGLD480 of Indian origin and is a natural gas turbo charged generator rated at 1000 KVA1 (Alternator), as per the manufacturers technical information below:

1 Manufacturers figures.

The CHP unit was installed around June 2007; it is housed in a self-contained block work room within the Energy Centre. The associated heat rejection units are located externally at high level above the main service access doors to the Energy Centre and are interconnected to the CHP unit to enable heat rejection. This unit is configured with six fans designed to cool the heating coil, it is manufactured by Heating & Cooling Coils Ltd and has an 80mm flow and return linked directly to the CHP. This CHP unit was supplied and installed by First Energy Limited. We understand that #### have an ongoing maintenance contract for the CHP, its associated equipment, pipework and controls. The selection of a CHP unit generally falls into one of two requirements, as follows:

Sized to suit electrical energy load required Sized to suit heat load required

Product Specifications for Natural Gas Guascor Gensets

Electrical KW

KVA at 0.8 p.f.

Rated Amperes at 415V.0.8 p.f.

Alternator Rating in KVA

Mechanical Brake KW

Engine Model

No. of Cylinders

Bore mm

Stroke mm

Cylinder Volume Ltrs.

Compr. Ratio

Weight Kg

812 1015 1421 1000 838 SFGLD 480

16 152 165 48 11.8:1 8450

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Other factors influencing selection include available space for plant, (which may have been the case in this instance); environmental issues such as noise nuisance to neighbours or adjacent buildings etc.

6.0 ANALYSIS OF HISTORICAL DATA AND CHP PERFORMANCE

6.1 Existing CHP Performance The bar chart (figure 6.1) shows the calculated monthly electricity cost savings for the period Dec 2012 – Oct 2013. The dark blue columns shows the savings in kwh generated units and the light blue columns takes into account other MEA charges.

Figure 6.1

6.2 Electrical Consumption Data (MSB1)

The bar chart (figure 6.2) illustrates the monthly electrical demands for MSB1 for the period Dec 2012 – Oct 2013. The light blue bars on the chart represent the electrical demand of MSB1 to which there is an existing CHP presently connected. The maximum electrical demand over the period Dec 2012 – Oct 2013 is 1,025kw

The light blue line represents the electrical contribution made by the CHP and varies between 57 – 80% of the total electrical demand.

It should be noted however that the rated electrical output of the CHP is 812kw and if fully utilised would meet approximately 90% of the electrical demand for this period. The existing CHP therefore appears to possess spare capacity which is not presently being harnessed to reduce the electrical operating costs of the site and is recommended to be investigated further. The additional electrical demands (108kva) for new works have been obtained from the M&E consultants and are represented by the dark blue bars on the chart.

£1

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08

£9

,55

8

£9

,69

5

£5

,84

5

£6

,42

2

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74

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45

£3

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£8

,76

8

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1,1

04

£4

,32

2

£0.00

£5,000.00

£10,000.00

£15,000.00

£20,000.00

£25,000.00

Oct-12 Nov-12 Dec-12 Jan-13 Feb-13 Mar-13 Apr-13 May-13 Jun-13 Jul-13 Aug-13 Sep-13

CHP ELECTRICITY COST SAVINGS OCT 2012 - SEPT 2013

CHP SAVINGS KWH ONLY

CHP SAVINGS INC OTHER CHARGES

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Figure 6.2

6.3 Electrical Consumption Data (MSB2) The light blue bars on the chart (figure 6.3) represent the electrical demand of MSB2 to which there is no CHP connected at present. The maximum electrical demand over the period Dec 2012 – Oct 2013 is 289kw The additional electrical demands (102kva) for new works have been obtained from the M&E consultants and are represented by the dark blue bars on the chart.

Figure 6.3

857 867 847 848 854 835 816

1,001 1013 10091025

108 108108 108 108

108108

108 108 108108

623

668 678657

685

635

691

524

582 569599

0

200

400

600

800

1,000

1,200

Dec-12 Jan-13 Feb-13 Mar-13 Apr-13 May-13 Jun-13 Jul-13 Aug-13 Sep-13 Oct-13

MONTHLY ELECTRICAL DEMANDSMSB1

DEC 2012 - OCT 2013ADDITIONAL ELECTRICAL MD

MONTHLY DEMANDS (MSB1)

CHP OUTPUT

ADDITIONAL ELECTRICAL MD:1) KEYLL DARREE EXTENSION (F) 20.0KVA2) NICU EXTENSION (E) 45.5KVA3) ENDOSCOPY UNIT (C) 27.0KVA4) BREAST CLINIC (D) 15.0KVA

RATED OUTPUT OF CHP (812KW)

261267

289276

249241 237

162

111118 122

102102

102102

102102 102

102

102102 102

0

50

100

150

200

250

300

350

400

450

500

Dec-12 Jan-13 Feb-13 Mar-13 Apr-13 May-13 Jun-13 Jul-13 Aug-13 Sep-13 Oct-13

MONTHLY ELECTRICAL DEMANDS (kw)MSB2

DEC 2012 - OCT 2013

ADDITIONAL ELECTRICAL MD

MONTHLY DEMANDS (MSB2)

ADDITIONAL ELECTRICAL MD:1) GEDDYN REESHT NEW EXTENSION (A): 72KVA2) NEW SOCIAL SERVICES DAY CENTRE (B) 30KVA

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The following table 6.3 shows the estimated maximum electrical demands for the site based upon known new works:

MSB1

Existing MD 1025 kva

Proposed MD 108 kva 1,133kva

MSB2

Existing MD 289 kva

Proposed MD 102 kva 391kva

Total MD 1,524 kva Table 6.3

6.4 Additional CHP installation (Option ‘A’) From the information shown in table 6.3 above it is possible to make a selection of a suitable rating machine based upon the total maximum estimated electrical demands of the site. Details of a 772kw (e) natural gas powered machine and estimated costs have been obtained from ENER-G Combined Power Limited and included elsewhere in this report.

In order that both the existing and additional CHP machines are loaded optimally it shall be necessary to carry out an electrical load assessment of the site in order to determine the optimum re-configuration of the LV switchboard. The exact location for the additional CHP requires to be determined but a containerised solution is presently envisaged and shall be sited as close as possible to MSB2. Heating services pipework and other mechanical works shall be required to interface the LTHW output with the existing heat stations and the cost for these works are presently excluded from this report.

6.4.1. Additional CHP Estimated Savings Summary (Option ‘A’) The estimated savings summary has been prepared by ENER-G Combined Power Ltd using the following present day energy costs and existing CHP performance values:

Cost of ‘on-peak’ electricity 13.42 p/kwh

Cost of ‘off peak’ electricity 7.76 p/kwh

Cost of natural gas 3.485 p/kwh

Electricity utilisation 70%

Steam utilisation 70%

LTHW utilisation 40%

Availability hours (per annum) 90% Table 6.4.1.1

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Parameter "Off Peak" Total / Mean

Capital £ -

Electricity Savings £ 104,498 £ 465,930

Electricity Export Income £ -

Electricity Generation Subsidy £ -

LTHW Savings £ 18,834 £ 56,501

LTHW Export Income £ -

LTHW Generation Subsidy £ -

Steam Savings £ 31,233 £ 93,699

Steam Export Income £ -

Steam Generation Subsidy £ -

Chill Savings £ -

Chill Export Income

Chill Generation Subsidy £ -

CHP Gas Cost (£ 135,804)(£ 407,412)

CHP CPS Cost £ -

GROSS ENERGY SAVINGS £ 18,761 £ 208,719

Maintenance (£ 80,000)

NET ENERGY SAVINGS (Pre Benefits) £ 128,719

CHP Fuel CCL Benefit £ -

Add. 'Ring-Fenced' Boiler CCL Benefit £ -

Triad Saving Benefit 0 £ -

Value of Carbon Benefit £ -

NET ENERGY SAVINGS (Post Benefits) £ 128,719

Simple Payback Period -

Discount Energy Purchase Cost £ -

NET ENERGY SAVINGS (Pre Benefits) £ -

NET ENERGY SAVINGS (Post Benefits) £ -

Parameter "Off Peak" Total / Mean

Electricity CO2 Abatement (tCO2) 646.7 1,940.0

LTHW CO2 Abatement (tCO2) 99.3 297.8

Steam CO2 Abatement (tCO2) 164.6 493.8

Chill CO2 Abatement (tCO2) -

Fuel CO2 Released (tCO2) (715.7) (2,147.1)

Total CO2 Abatement (tCO2) 194.8 584.5

(1,431.4)

389.6

329.2

1,293.3

198.5

"On Peak"

0

£ 189,958

(£ 271,608)

£ 62,466

£ 37,668

£ 361,433

"On Peak"

Table 6.4.1.2

6.4.2 Additional CHP Simple Payback (Option ‘A’)

Additional CHP (MSB2)

Supply & delivery (ENER-G Combined Power Ltd) £459,000*

Weatherproof acoustic enclosure £75,000*

Installation & Commissioning £125,000*

Ancillaries £15,000*

Total estimated cost £674,000

* Budget costs

Total estimated capital cost £674,000

Annual estimated energy savings (see table 6.4.1.2) £128,719

Simple payback 5.25 years

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6.5 Additional CHP installation (Option ‘B’)

Figure 6.5

From the information shown in figure 6.5 above it is possible to make a selection of a suitable rating machine based upon the base load electrical demands of electrical switchboard ‘MSB2’ and include an allowance for the estimated electrical demands for the new developments. Details of a 230kw (e) natural gas powered machine and estimated costs have been obtained from ENER-G Combined Power Limited and included elsewhere in this report. The CHP suppliers have advised that it is uneconomic on smaller rated CHPs to recover the high grade heat from the engine exhaust for the purposes of generating steam via a waste heat boiler. Savings in steam mitigation have therefore been excluded from the savings summary. In addition it may be seen from the savings summary that operating the CHP in “off-peak” hours produces a net loss so the unit should only run during “on-peak” periods. The maintenance price reflects running in the peak time only, however, if the electricity tariffs become more favourable so that running in the off-peak period can provide useful savings then the CHP maintenance costs will also increase accordingly.

The exact location for the additional CHP requires to be determined but a containerised solution is presently envisaged and shall be sited as close as possible to MSB2. Heating services pipework and other mechanical works shall be required to interface the LTHW output with the existing heat stations and the cost for these works are presently excluded from this report. The suppliers’ budget capital cost for a 230kwe CHP include for the following items only:

ENER-G 230 genset;

Low noise weatherised container rated to 65dBA @ 1m;

Low noise heat rejection radiator rated to 65dBA @ 1m;

Air fuel ratio controller and catalyst for low NOx emissions;

Low noise silencers;

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Power modulation panel;

DRV and 3 port valve for lower than 90°C flow and 80°C return;

Gas and heat meters;

G59/2 application fee;

Supply, delivery and commissioning only.

6.5.1. Additional CHP Estimated Savings Summary (Option ‘B’) The estimated savings summary has been prepared by ENER-G Combined Power Ltd using the following present day energy costs and following CHP performance values:

Cost of ‘on-peak’ electricity 13.42 p/kwh

Cost of ‘off peak’ electricity 7.76 p/kwh

Cost of natural gas 3.485 p/kwh

Electricity utilisation 100%

Steam utilisation n/a

LTHW utilisation 40%

Availability hours (per annum) 90% Table 6.5.1.1

Parameter "On Peak" "Off Peak" Total / Mean

Capital £

Electricity Savings £153,450 £44,366 £197,816

LTHW Savings £37,668 £18,834 £56,501

CHP Gas Cost (£131,479) (£65,740) (£197,219)

GROSS ENERGY SAVINGS £59,638 (£2,540) £57,098

Maintenance (£20,000)

NET ENERGY SAVINGS £37,098

Parameter "On Peak" "Off Peak" Total / Mean

Electricity CO2 Abatement (tCO2) 549.1 274.5 823.6

LTHW CO2 Abatement (tCO2) 198.5 99.3 297.8

Fuel CO2 Released (tCO2) (692.9) (346.4) (1,039.3)

Total CO2 Abatement (tCO2) 54.7 27.4 82.1 Table 6.5.1.2

6.5.2 Additional CHP Simple Payback (Option ‘B’)

Additional CHP (MSB2)

Supply & delivery (ENER-G Combined Power Ltd) £210,000*

Weatherproof acoustic enclosure £50,000*

Installation & Commissioning £100,000*

Ancillaries £10,000*

Total estimated cost £370,000

* Budget costs

Total estimated capital cost £370,000

Annual estimated energy savings (see table 6.5.1.2) £37,000

Simple payback 10 years Table 6.5.2.

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6.6 Heat Demands versus Average External Temperatures The following chart (figure 6.6) shows the daily average external temperatures plotted alongside the daily heat demands for the site for the month of January 2013. N.B. historical temperature records for the months of analysis were obtained from the nearest weather station website. As may be seen the temperatures rise and fall in a wave effect during the month of January 2013. The heat demand chart would be expected to show an approximate converse shape owing to the BMS controlling the output of the boilers to meet the heating demands of the site.

This finding may require some further investigation carried out on the building management system to ensure that the optimisation feature of the BMS is functioning properly.

Figure 6.6 Heat Demand vs Average External Temperature Chart Jan 2013

6.7 Gas Consumption Data

The heat generated by the CHP in day to day operation is sometimes referred to as ‘free heat’ because it is a by-product of the generation of electricity. The light red coloured bars on the chart represent the amount of gas consumed by the CHP for generating electricity and heat and the deep red coloured bars represent the quantity of gas consumed by the heating boilers for meeting the LTHW heating, domestic hot water and process steam demands. As can be seen from the following chart (figure 6.7) the heat output from the CHP is reasonably consistent for the latter part of the month of January 2013 and accounts for approximately 40% of the total heat demand for the site. In March 2013 the CHP contributed 36% of the total heat demand and in May 2013 the CHP contributed 48% of the total heat demand.

Minimum and maximum external temperatures have been overlaid on the gas consumption charts for informational purposes only. For the same reasons discussed in 6.6 above one would expect to see a fairly close correlation between the heating demands and recorded external temperatures.

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Figure 6.7 Gas Consumption Chart January 2013

6.8 CHP Waste heat vs Cooling Capacity

The monthly gas demands (figure 6.8.1) show that demands for heat from the main boilers is significantly reduced in the summer months. By comparing the excess heat chart for August 2013 (figure 6.8.2) shows that a significant amount of the heat energy supplied by the CHP is presently being liberated to the atmosphere rather than being put to any useful purpose.

Figure 6.8.1

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Nov-12 Dec-12 Jan-13 Feb-13 Mar-13 Apr-13 May-13 Jun-13 Jul-13

MONTHLY GAS DEMANDS (kwh)NOV 2012 - JULY 2013

CHP ELEC

CHP HEAT

BOILERS + STEAM

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Figure 6.8.2

Suppliers of packaged cooling equipment have advised that both the temperature and flow volume of the CHP waste heat for the period under analysis represents sufficient energy for either an absorption or adsorption chiller to provide an additional 423kw of cooling capacity. Ongoing data logging of the CHP waste heat water flow and supply & return temperatures are recommended to be carried out further in order to assist with the optimum selection of chiller. 6.9 Adsorption or Absorption Water Chillers? An article reprinted from the September 2009 online edition of Cogeneration & On-site Power Production provides an excellent description of the modes of operation, benefits and drawbacks of both adsorption and absorption water chillers (see appendices). In summary the adsorption machine incorporates a dry desiccant in the form of naturally occurring and environmentally benign zeolite or silica gel and the absorption design utilise a liquid desiccant in the form of lithium bromide which is not environmentally benign. For reasons of environmental sustainability Epsilon Consultants (IOM) Ltd recommend the selection of an adsorption chiller utilising zeolite or silica gel as the desiccant. A significant cost premium is attached to the adsorption chiller for reasons of the design being not so well established and relatively few machines having been supplied. The adsorption design also requires a chilled water buffer vessel to be incorporated owing to the production of chilled water being intermittent. Proposals have been received from suppliers of both types of chiller designs and are included elsewhere in this report. The suppliers of the adsorption chiller (Weatherite Ltd) have advised the following details (table 6.9.1) concerning the estimated electrical demands of the equipment parasitic loads:

807

679

818 818 818

780802 801 798 800 800 800 805 805 796 804 801 801 801 799 803 798 800 799 799 799 799

830

788808 799

0

5

10

15

20

25

0

100

200

300

400

500

600

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800

900

EXCESS CHP HEAT (M3) TO HEAT REJECTION PLANT AUG 2013WATER VOLUME

MEAN EXTERNAL TEMP

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ADSORPTION CHILLER 0.2 KW

PRIMARY PUMPS CHW 7.5 KW

SECONDARY PUMPS CHW 7.5 KW

PRIMARY COOLING PUMPS 30.0 KW

SECONDARY COOLING PUMPS 18.5 KW

HOT WATER PUMPS 18.5 KW

COOLING TOWER FANS 22.0 KW

TOTAL CONNECTED LOAD 104 KW

TOTAL RUNNING LOAD 60 KW

Table 6.9.1

The estimated costs for the supply of both types of chillers exclude the following items:- i. Offloading costs (crane & temporary storage)

ii. Adiabatic dry cooler iii. Pumps, fans & controls iv. Small air compressor v. Installation

vi. Pipework interface with existing systems vii. BMS interface

viii. Weatherproof container or enclosure

6.10 Simple Payback Calculation The following are simple payback calculations based upon the estimated capital costs for both chiller types and the electricity tariffs currently in force:

6.10.1 Option ‘A’ Adsorption chiller (Weatherite + Dry Cooler)

Adsorption Chiller

Supply & delivery (Weatherite Ltd) £195,000

Adiabatic dry cooler (Carter Env Engineers Ltd) £126,000

Installation & Commissioning £50,000*

Ancillaries £15,000*

Total estimated cost £386,000*

* Budget cost

Annual energy costs saved

1 M3 of ice storage = 93kwh. 43 M3 = 4,000kwh = 9.45hrs charging

8 hours x off-peak rate (£0.0776) x 423kw x 274 hours* £71,952

1.45 hours x on-peak rate (£0.1342) x 423kw x 274 hours* £22,553 £94,505

Less parasitic demands for adsorption chiller: 8 hours x on-peak rate (£0.1342) x 60kw x 274*

£17,650

Net annual saving £76,855

Assume 9 months per annum cooling cycle

Simple payback calculation

Total estimated cost £386,000

Annual estimated running cost £94,505

Less parasitic demands £17,650 £76,855

Simple payback 5 years

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6.10.2 Option ‘B’ Absorption chiller (Toshiba Carrier + cooling tower)

Absorption Chiller

Supply & delivery (Toshiba Carrier Ltd) £75,000

Forced draft cooling tower (Carter Env Engineers Ltd) £35,000

Installation & Commissioning £25,000*

Ancillaries £15,000*

Total estimated cost £150,000*

* Budget cost

Annual energy costs saved **

1 M3 of ice storage = 93kwh. 43 M3 = 4,000kwh = 9.45hrs charging

8 hours x off-peak rate (£0.0776) x 423kw x 274* £71,952

1.45 hours x on-peak rate (£0.1342) x 423kw x 274* £22,553 £94,505

Less parasitic demands for absorption chiller: 8 hours x on-peak rate (£0.1342) x 60kw x 274*

£17,650

Net annual saving £76,855

Assume 9 months per annum cooling cycle

Simple payback calculation

Total capital estimated cost £150,000

Annual estimated running cost £94,505

Less parasitic demands £17,650 £76,855

Simple payback 2 years

** The saving in electricity running costs may be calculated as the annual cost of electricity that would be paid by providing an additional 423kw electrical chiller and ice storage vessel of the same specification as presently exists.

6.11 Adiabatic cooling It should be noted that both adsorption and absorption chiller designs require a cooling tower (forced draft or induced draft) or an adiabatic dry cooler to be incorporated into the installation in order to reject the low grade heat from the condenser cycle. A water operated cooling tower of either forced draft or induced draft design presents an inherent risk of legionella unless a properly managed maintenance regime is implemented. A ‘sprayless’ design of adiabatic dry cooler, however, does not carry an intrinsic risk of legionella because of the closed circuit type of design although there is a premium to pay in terms of capital costs and running costs.

Budget proposals have been received from Carter Environmental Engineers for various specification water towers and adiabatic dry coolers and cooling towers are included elsewhere in this report.

For reasons of the elimination of the risk of legionella Epsilon Consultants (IOM) ltd recommend the selection of an adiabatic dry cooler.