Drive for Energy Efficiency

Roger S H Lai23.04.2007

Why need to pay attention to energy efficiency?

1. Try to arrest the runaway increase of carbon dioxide. If the world does not do anything now and let business as usual, then by 2050, there will be so much climate change that the situation would be irreversible. (El Gore, IEA study: Energy Technology Perspectives 2006 :Scenarios and Strategies to 2050)2. Fossil fuel is finite

Reference Scenario: Implications for CO2

Emissions

Half of the projected increase in emissions comes from new power stations, mainly using coal & mainly located in China &

India

Increase = 14.3 Gt (55%)

0

10

20

30

40

50

1980 1990 2004 2010 2015 2030

Gt o

f CO

2

Coal Oil Gas

Alternative Policy Scenario: Global Savings in Energy-

Related CO2 Emissions

Improved end-use efficiency of electricity & fossil fuels is accounts for two-thirds of avoided emissions in 2030

Alternative Policy Scenario

Reference Scenario

Increased nuclear (10%)Increased renewables (12%)Power sector efficiency & fuel (13%) Electricity end-use efficiency (29%)

Fossil-fuel end-use efficiency (36%)

26

30

34

38

42

2004 2010 2015 2020 2025 2030

Gt o

f CO

2

Ways to save energy and reduce emission (1)

Use a different way of energy generation rather than fossil fuel: e.g. by 2030, contributions of reduction from: Renewable energy (12%), nuclear (10%)Improve the fuel to energy conversion of fossil fuel.Improve the loss of energy transmission to end use: Improve energy efficiency at end-use: potential of contributing up to 65% of the projected growth reductionCO2 sequestration (probably not mature enough to be significant)

Compounding losses…or savings—so start saving at the downstream end

What other countries are doing? (1)

Advanced countries have set ambitious goals. One scenario studied in Germany is:a) maintain current level of total energy consumption while maintaining economic growth, build no more fossil fuel power stations;b) phase out existing nuclear stationsc) build renewables to replace (b)d) improve energy efficiency by 50% by 2050 to meet new energy needs

What other countries are doing? (2)

UK: similar consideration. Carbon tax introduced. Aim to reduce carbon dioxide by 50% by 2050.

USA: e.g. Government buildings to save energy of 2% per year from 2005 to 2015: that is 20% in ten years.

China: Laws for RE and for EE established in recent years.

Are these energy efficiency targets realistic?

With innovative approaches, and changes in conventional installation practices, such targets are realistic.Cases quoted by Rocky Mountain Institute: over 50% energy eff. improvement achievedCase quoted by Scientific America in 9/2006 issue: factory in Germany 43% improvement.Our studies : A simple novel project at BATCX achieved 16% improvement Let’s see some examples

LightingT5 tubes much more energy efficient“Plug and enhance” devices now availableElectronics ballasts incur less lossUse of reflective luminairesMuch of the existing lighting systems could be retrofittedSuitable de-lamping

Fluorescent Tubes Lighting (1)

Power (lamp only)

Length(mm)

600 900 1200 1500

T8 18W 30W 36W 58W

T5 14W 21W 28W 35W

Fluorescent Tubes Lighting (2)

CoatingHalo-phosphate (standard T8)Tri-phosphate (standard provision for T5)

Halo-phosphate

Tri-phosphate

1200 mm T8 2850 lumen 3250 lumen

1150 mm T5 N. A. 2600* lumen

Electronics ballastsPotential Energy Saving

Take 1200mm system as an example

Standard T8 EMB to T8

EB

Standard T8 EMB to T5

EB

Standard T8 EB to T5 EB

44W to 36WSave 18%

44W to 31WSave 30%

36W to 31WSave 14%

Plug and Enhance (7)PnE not using QEBIt use tri-phosphors T8 tube with shorter than standard length and lamp power together with an additional EMB11% reduction in energy consumption

Use of LED Exit Signs

Conventional Exit Sign

18W 2-year service life

LED Exit Sign 3W 5-year service life Estimated savings: 24,800 kWh/annum

Replacement of Incandescent LampsIncandescent lamps

CFLs

Incandescent lamps

CFL

Lamp wattage (W) 40 9

Total circuital power (W)

1,672 264

Lighting level (lux) 1,300 1,600

Estimated Savings 10,000 kWh/annum

A/C system (1)Design

Water-cooled a/c system more energy efficient than air-cooled a/c system (more than 15%, up to 30% possible). Use of fresh water cooling towers.Improved piping and ductwork design, minimize bends, use larger size pipes and ducts.Do not excessively oversize the pumps and motors.

A/C systems (2)New design and retrofit

Automatic tube cleaning deviceUse of PROA to reduce scaling on the refrigerant side of the heat exchangerVSD for the air flow control and liquid flowCO2 sensing and controlOperational control: water temperature reset, air temperature reset, air duct static pressure reset

Typical areas for big savings

Thermal integrationPower systemsDesigning friction out of fluid-handling systemsWater/energy integrationSuperefficient and heat-driven refrigerationSuperefficient drivesystemsAdvanced controls

Let’s look at one example: pumping systems (information from Rocky Mountain Institute www.rmi.org)

Why focus on pumping? examplesPumping is the world’s biggest use of motorsMotors use 3/5 of all electricityA big motor running constantly uses its capital cost in electricity every few weeksRMI (1989) and EPRI (1990) found ~1/2 of typical industrial motor-system energy could be saved by retrofits costing <US$0.005 (1986 $) per saved kWh—a ~16-month payback at a US$0.05/kWh tariff. Why so cheap? Buy 7 savings, get 28 more for free!Downstream savings are often bigger and cheaper—so minimize flow and friction first

99% 1%

hydraulic pipe layout

vs.

Then minimize piping friction

EXAMPLE

1%

Boolean pipe layout

optional

99%

New design mentalityNew design mentality

• Redesigning a standard (supposedly optimized)industrial pumping loop cut power from 70.8 to 5.3 kW (–92%), cost less to build, and worked better

Just two changes in design mentality

• Redesigning a standard (supposedly optimized)industrial pumping loop cut power from 70.8 to 5.3 kW (–92%), cost less to build, and worked better

Just two changes in design mentality

New design mentality, an example

1. Big pipes, small pumps (not the opposite)1. Big pipes, small pumps (not the opposite)

No new technologies, just

two design changes

2. Lay out the pipes first, then the equipment (not the reverse)

2. Lay out the pipes first, then the equipment (not the reverse)

No new technologies, just two design changes

Fat, short, straight pipes — not skinny, long, crooked pipes! Benefits counted

92% less pumping energyLower capital cost

“Bonus” benefit also captured70 kW lower heat loss from pipes

Additional benefits not countedLess space, weight, and noiseClean layout for easy maintenance accessBut needs little maintenance—more reliableLonger equipment life

Count these and save…~98%?

Fat, short, straight pipes — not skinny, long, crooked pipes! Benefits counted

92% less pumping energyLower capital cost

“Bonus” benefit also captured70 kW lower heat loss from pipes

Additional benefits not countedLess space, weight, and noiseClean layout for easy maintenance accessBut needs little maintenance—more reliableLonger equipment life

Count these and save…~98%?

This case is archetypicalMost technical systems are designed to optimize isolated components for single benefitsDesigning them instead to optimize the whole system for multiple benefits typically yields ~3–10x energy/ resource savings, and usually costs less to build, yet improves performanceWe need a pedagogic casebook of diverse examples…for the nonviolent overthrow of bad engineering (RMI’s 10XE (“Factor Ten Engineering” project—partners welcome)

Which of these layouts has less capex & energy use?

Condenser water plant: traditional design

to chiller

to chiller

to chiller

return from tower

return from tower

return from tower

• Less space, weight, friction, energy

• Fewer parts, smaller pumps and motors, less installation labor

• Less O&M, higher uptimereturn

from tower

to chiller

return from

tower

…or how about this?

Summary of improved piping and ductwork

Reduce bends to minimize obstructions to flowUse larger diameter pipes and smaller pumps/motors

Power proportional to v3

Layout the pipe and duct first before laying out the components

Trial of the concept at BATCXBATCX as the trial site for “big pipe small pump’conceptBATCX was commissioned in 19992 x 330kW sea water-cooled ammonia chiller1/F sea water pump room pumping cooling water to 4/F chiller plant room

BATCX – Sea Water Flow Schematic Diagram

Proposed Modification

Existing ConfigurationWate

r Path

No. of fittings

12 x 90o

2 x branches2 x 45o

22 x branches2 x 45o

32 x 90o

2 x branches2 x 45o

Proposed Design

Water

Path

No. of fittings

12 x 90o

1 x branch

22 x 90o

2 x branches

3 2 x branches

Proposed Modification - 1/F Pump Roomsome bends eliminated

Before After

Proposed Modification - 4/F Chiller Plant with one section of pipe

enlarged

Before

After

Impeller Trimming (1)

The operating point is shifted to the right after the pipe work modification as frictional loss is reduced and the flow is increased

The impeller should be trimmed down as to reduce the flow back to the point before the pipe work modification

Impeller Trimming (2)

The distance between the original pump curve and the one extrapolated from the new operating point dictates how much the impeller should be trimmed down

Impeller Trimming (3)

The impeller was trimmed down from 228.6mm to 221.6mm (7mm) in diameterImprovement recorded ~8%

Impeller Trimming (4)

12.High Efficiency MotorP erformance Curve

72.0%

74.0%

76.0%

78.0%

80.0%

82.0%

84.0%

86.0%

88.0%

90.0%

50% Load 75% Load Full load

Loading

Effici

ency

Existing Motor High Efficiency Motor

EFFI of ECMEMP

Power Consumption of Sea Water Pump #2 at Different Stages

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

Before Pipe Work ModificationAfter Pipe Work ModificationAfter Impeller Trimming After Installation of HighEfficiency Motor

Pow

er

Consu

mpti

on (

kW

)

Conclusion from the trial project in BATCX

Energy saving from the modified changes in reducing pipe bends, and enlarging one section of the pipe gives about 8% improvement in energy efficiency.Use of high-efficiency motor gives another 8%More energy reductions could be achievable if the pipework is designed from scratch.

Water-cooled a/c systemGovernment conducted a study in 1999, water-cooled a/c much more efficient than air-cooled a/cLaunched the pilot scheme for using fresh water cooling towers for water-cooled a/c systemsSome installed systems have achieved good results

Development

Year 2000 2001 2002 2003 2004 2005

Pilot Scheme Designated Areas

6 11 28 45 57 71

Non-domestic Gross Floor Areas (m2)

9 M 16 M 28 M 40 M 52M 70 M

Coverage of Territorial Non-domestic Gross Floor Areas

12% 18% 30% 41% 53% 70%

Private Sector Participation

November 2005 figures46 Applications from New Development

1,489,556 m2 (51% of newly constructed buildings)

107 Applications from Existing Development

3,538,083 m2 (5% of existing buildings)

Achievement (1)

Year 2000 2001 2002 2003 2004 2005 Total

No. of Application

4 4 7 37 79 53 184

No. of Applications approved by WA in principle

4 4 4 27 37 25 101

No. of completed installations

0 2 3 2 15 12 34

Achievement (2)Completed cooling capacities: 362,533 kWAnnual energy saving: 35,120,000 kWh/yrAnnual emission reduction:

CO2 24,584 tonnes/yrNOX 63 tonnes/yrSO2 49 tonnes/yrParticulate 3 tonnes/yr

Benefits of Pilot Cases

1. Lower heat rejection system energy cost for replacing air-cooled dry radiators by cooling towers : 88%

2. Lower condenser water temperature : 8oC in summer

3. Improve chiller plant efficiency : 23%

A shopping mall

12 x 2,333kW cooling towers (total heat rejection: 27,996kW)

Annual energy saving: 4,870,000 kWh/yr

A commercial

complex

9 x 3,336kW cooling towers (total heat rejection: 30,024kW)

Annual energy saving: 4,650,000 kWh/yr

Benefits

Savings of three pilot cases as compared with air-cooled plant – 9, 520 MWh/yr

Equivalent to 9 HEC wind turbines in Lamma Island

Automatic Tube Cleaning System

Shell and Tube Condenser

Tube Cleaners Collector and Injector

Tube cleaner Trap

To drain

Condensing Water

Injection pressure (from pump, air compressor, or dynamic pressure of condensing water)

PLC Controller

Tube cleaners

Common Configuration of Ball Type Automatic Tube Cleaning System

Automatic Tube Cleaning System

Ball type tube cleaner

Brush type tube cleaner

Results of using automatic tube cleaning system

One Grade A office building in Eastern District with a water-cooled A/C system using cooling towers has improved the COP of the A/C system from

0.76 to 0.8 kW/ton -> 0.72 kW/ton

EMSD is trying out this in some venues

New initiatives in Improvement of Energy Efficiency for Air-conditioning Systems

Topics

Static Pressure Reset Controls for Variable Air Volume Supply Systems

All Variable Speed Chilled Water Plant Controls

High Efficiency Centrifugal Compressor Systems

Air-cooled Chillers Condensing Temperature Controls

Constant Static Pressure Controls

Conventional, Constant Static Pressure (CSP) VAV, A/C System Design:Maintain static pressure in main air duct at constant pressureconstant pressure

Area of Concern:Unnecessary high duct static pressure occurs in partial load condition and results in energy wastage

Reducing Static Pressure (RSP) VAV A/C Controls:

Resetting of duct static pressure set point according to actual on-line condition of the VAV boxes within the zone

Reduction of duct static pressure results in reduction of fan speed

Accomplishment of energy saving as a result of fan speed reduction of variable speed drives (VSD)

RSP VAV A/C Controls

Operating points with and without RSP control

Required fan pressure reduced without change of flow rate

RSP VAV A/C Controls

Relationship Between Supply Air Pressure and Fan Speed

Relationship between supply air pressure and fanspeed

76.85 91.74 128.52

174.22

224.00

254.33

0.0050.00

100.00150.00200.00250.00300.00

20 25 30 35 40 45 50Frequency (Hz)

Pre

ssu

re (

Pa)

Pressure (Pa)

Relationship Between Fan Power Consumption and Fan SpeedRelationship between fan power consumption

and fan speed

10.22

8.72

6.34

4.423.152.16

0.002.004.006.008.00

10.0012.00

20 25 30 35 40 45 50Frequency (Hz)

Po

wer

Co

nsu

mp

tio

n(k

W)

Power Consumption (kW)

Comparison of Hourly Average Static Pressures Between RSP and CSP Modes

Average Static Pressure under RSP and CSP

225

196

159

114132

73

250

179

161

166

144

157 145 151

169181

251

242244

255

248 249 252

256 253

234

0

50

100

150

200

250

300

07:30 08:30 09:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30 18:30 19:30Time

Su

pp

ly a

ir p

ress

ure

(P

a)

Average static pressure under RSP Average static pressure under CSP

Comparison on Daily Performance with same Cooling-degree Hour

CSP mode RSP mode

Averaged outdoor temperature (deg.C)

27.6 27.4

Operating Schedule 0730 – 1900hrs. 0730 – 1900hrs.

No. of Daily Cooling-degree Hours (CDH)

147.65 145.60

Total kWHr 90.86 66.65

kWhr/CDH 0.62 0.46

Saving 25.8%

Preliminary Findings on Energy Performance

CSP mode RSP mode

No. of sampling days 25 7

Total No. of Cooling-degree Hours (CDH)

4,044 968

Total kWHr 2,225 415

kWhr/CDH 0.55 0.43

Saving 21.8%

All variable speed chilled water plant control

Existing practice, chiller pumps are not variable speed. Chiller motors are large, and VSD expensive. Moreover, chiller variable speed control are not common.All variable speed system means that the chiller pump is variable speed, the chiller water supply is variable speed, the cooling water circulation is variable speed.With all these variables, the problem is how to optimize the control.

1. Natural Curve Sequencing

Methodology for determining the best operation sequence and loading of equipment with respect to kW/ton

Equipment is operated as close as possible to its natural curve

2. Equal Marginal Performance Principle by means of Demand Based Control

Methodology for determining the operation speed of each piece of equipment so that the chiller plant is operating at its most efficient configuration

Operation of the all-variable speed chiller plant is optimized based on the actual demand for cooling

Theory

Condenser

F

TT

F

T F

T F

T F

T F

T F

T F

VFD

VFD

VFDVFD

VFD

VFD

JohnsonControlDDC

Hartman Loop

Optimum Energy

Controller

Existing CCMS

Existing chiller plant power consumption :

0.8 kW/TR

Estimated power consumption of chiller plant with Variable Speed Control at 50% load and 70oF condensing water temperature: 0.65 kW/TR

Around 20% improvement in chiller efficiency is expected

Estimated energy saving : 500,000 kWh/year

Energy Saving

High Efficiency Centrifugal Compressor System

69

Features Turbocor compressor system claims to be an energy efficient technology for air-cooled and water-cooled chillers. The system mainly comprises:

VSD-controlled magnetic bearing compressors

Control program to control the chiller operation including load sharing among compressors

Electronic expansion valve

Oil free operation

Inverter Speed Control

Synchronous

Brushless DC

Motor

Motor and

Bearing Control

Inlet Guide Vanes

2-stage Centrifugal Compressor

Pressure and Temperature

Sensors

Components of the Compressor

Operating speed ranges from 18,000 to 48,000 RPM

Inverter is built into the compressor

Low starting current of 2A compared with 500A on a conventional compressor

The slower the compressors speed, the greater the efficiency

Provide best part load efficiency

Speed Energy3

Variable speed nature of the high efficiency centrifugal compressor

72

ASHRAE study (Research Project 361) Typical lubricated chiller circuits show

reductions in design heat transfer efficiency of 15%-25%, as lubricant accumulates on heat transfer surfaces, denatures and blocks normal thermodynamic transfer processes

Problems associated with Oil

Typical Integrated Part Load Value (kW/ton)

Reciprocating Compressors : 0.9 to 1.2

Screw Compressors : 0.6 to 0.7

Turbocor : 0.4

74

Suitable Application of the new high speed chiller

Replacement of old conventional chillers

Replacement of old compressorsOne example under consideration:

Existing chiller plant power consumption: 1.2kW/TR

Estimated power consumption of chiller plant with Turbocor compressor: 0.4kW/TR

Estimated energy saving:50,000kWh/year

Are the targets realistic?

Conclusion: Target realistic, but we need to be courageous enough to adopt new technologies and overcoming institutional hurdles.Also new technologies will be developed to further improve the energy efficiency in future (say, in the next 20 years), hence situation remains optimistic

How do we go about it? (1)Set ourselves a vision and devoted to it. Senior management to lead and provide support.In the past, we might not have a vision. We may just be trying out and be satisfied with some minor improvements since we do not have a vision or target. We may also just rely on good housekeepingNow we should think in terms of technology, think in longer terms, and think about corporate responsibilities.

How do we go about it? (2)Know the subject extensively. Have a thorough understanding.Be vigilant on development of new energy efficiency technologies.Think of how to try them out.Be serious and meticulous about M&V, especially in establishing the baselines before change, and then measurement after change.

How to go about it (3)?

Verify the long term efficacy of the initiative.

Pilot scheme.If there is no contractor supplying the equipment we want, try to consider buying the equipment in HK and install them ourselves.

Find legitimate ways to overcome institutional barriers.

Institutional barriers that may hinder changes and

innovationTraditions and established practices and designsMarket structure and conditions may not encourage adoption of innovative products HabitsWe need some courage to adopt changes

Thank you.