Energy Efficiency in CMC Water Supply/Distribution System

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Energy Efficiency in CMC Water Supply/Distribution
System EM Piyasena RA Attalage (Sri Lanka Energy
Managers Association)
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OUTLINE

• Scope
• Walk-through and Billing Audit
• Detailed Audit
• Results
• Recommendations

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WALK-THROUGH AND BILLING AUDIT

• General Layout up to Main Distribution Points

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WALK-THROUGH AND BILLING AUDIT..Overall Layout
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CMC Distribution System
WALK-THROUGH AND BILLING AUDITcontd
Dehiwala
LABUGAMA
15 MGD
Maligakanda
Jubilee
8 MGD
KALATUWAWA
Eliehouse
Total 62.5 MGD
AMBATELE
107 MGD
Greater Colombo others
Total 67.5 MGD
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Eliehouse-1
WALK-THROUGH AND BILLING AUDITContd

• Share of Distribution of Each Reservoir

Total Average Production is 109 MGD (20588 m3/hr)
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WALK-THROUGH AND BILLING AUDITContd

• Composition of Monthly Production Cost
• Ambathale Treatment Plant

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Electricity Consumption Variation
WALK-THROUGH AND BILLING AUDITcontd
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WALK-THROUGH AND BILLING AUDITContd
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WALK-THROUGH AND BILLING AUDITContd
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DETAILED AUDIT

• Preliminary Investigation

• Three major pump sets Maligakanda , Church Hill
  and New intake
• Electricity Input, pump head, flow rate and pump
  speed for parallel and single operation,
• Pump performance evaluation
• Power factor measurements
• Optimization of clarifiers
• On-line calibration of flow meters

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Expected and Measured Efficiencies
DETAILED AUDITcontd
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Power Factor MeasurementexNew Intake to
Ambathale Treatment Plant
DETAILED AUDITcontd
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RESULTS
PRELIMINARY RESULTS

• Low power factors at loads
• Overall operating efficiencies are lower than the
  expected.
• Large variation in energy intensities of pumping.
• Water loss due to back wash, sludge drainage
  lab testing is around 7 MGD.
• NRW is around 50 in Colombo city distribution
  system

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Optimizing energy intensity of pumping
RESULTScontd

• Range of monthly production varies from 101.17
  111.27 MGD
• Range of monthly energy consumption 4.3 6.0 GWh
• Monthly specific energy consumptions vary from
  0.31-0.42 GWh/m3
• Same production has distinctly different energy
  consumption values
• Enhance clarification during high turbidity
  period
• Annual savings of 2 GWh, Rs. 16.7 million
• Cost involved Rs.16 million

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Power Factor improvement
RESULTScontd

• Low Power Factors (0.79 0.83) were found in the
  new intake
• Potential monthly max. demand reduction by
  improving power factor to 0.95 is 1.52 MVA
• Total monthly savings is Rs.0.6 million
• Simple payback is 2.4 months

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Improving overall efficiency of pumping units.
RESULTScontd

• Measured operating overall efficiencies of all
  the pumps (ranging 40 to 75)
• Improving overall efficiencies
• Church-hill
• Annual savings of 0.94GWh, Rs.7.5 million
• Simple payback for impeller sizing, 08 months
• Simple payback for pump replacement, 07years

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Improving overall efficiency of pumping units.
RESULTScontd

• Improving overall efficiencies
• Maligakanda
• Annual savings of 0.90 GWh, Rs.7.2 million
• Simple payback for impeller sizing, 06 months
• Simple payback for pump replacement, 5.5years
• Extrapolation..Ambatale Plant
• Annual savings of 6.3 GWh
• (Comparison monthly mean consumption of 5 GWh)

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On-site calibration flow meters.
RESULTScontd

• Verification by on-line calibration
• First results show that flow meter readings
  overestimate by 15
• Study to be continued for confirmation.
• If so, estimated saving potentials will be much
  higher with low NRW losses.

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Water consumption reduction by end users
RESULTScontd

• End user survey through a questionnaire
• Simple statistical analysis carried out
• Estimated end-use water saving potential, 17.
• Detailed study is required to extrapolate the
  results to the CMC distribution areas.
• Identify cost effective, efficient end use
  methods/strategies with the view to conserve

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RECOMMENDATIONS

• Low cost no cost options
• Enhance clarification. Further investigation of
  the fluctuation of energy per unit product is
  necessary.
• Continue the calibration work to confirm
  results.
• Water consumption reduction by end users.
• Medium cost options
• Power factor improvement
• Further investigation of NRW
• High cost options
• Replacement of low efficient pumps with new pumps
• In-situ electricity generation? (study)
• Diesel Engine driven pumps? (study)

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Thank You
Co-operation and assistance extended by the
National Water Supply and Drainage Board is
greatly acknowledged.