Water Pumping Retrofit to cut CO2 Emissions - Kolkata
Municipal pumping is one of the areas where there is tremendous potential to improve energy efficiency. In general, pumping systems contribute to more than half of all electricity consumption in municipalities. In light of this knowledge, a pilot energy efficiency study was undertaken at one of the Booster Pumping Stations in the city of Raja Subodh Mullick, Square Booster Pumping Station.
Raja Subodh Mullick (RSM) Square Booster Pumping Station (BPS)
The RSM Square pumping station was established in 1981. It receives treated water from Tallah pumping station through a 45" diameter pipeline. This water is primarily stored in an underground reservoir with a capacity of 6 million gallons and is pumped directly into the distribution system. A portion of the water received from Tallah pumping station is directly boosted to the distribution network by a Line booster pump installed in the pump house. The distribution system serves the drinking water needs for about 336,000 people, comprising for the population in the command area.
Energy Consumption Status - A Trail Based Measurement and observations
The study for energy consumption status was based on the different measurements conducted at RSM square BPS (Refer to Table No.1). Average water intake at RSM Square BPS from Tallah pumping station, as per Kolkata Municipal Corporation (KMC) data, is 29.3MG/Day, where as the quantity pumped out from the BPS based on the actual measurements carried out is 27MG/Day. Thus, 2.3MG/Day (i.e. 7.85% of the water pumped out from Tallah to RSM Square BPS) becomes Unaccounted For Water (UFW) even before being received at RSM Sq. BPS.
Table No.1 Details of the Measurements at RSM BPS
Raja Subodh Mullick (RSM) Square Booster Pumping Station (BPS)
The RSM Square pumping station was established in 1981. It receives treated water from Tallah pumping station through a 45" diameter pipeline. This water is primarily stored in an underground reservoir with a capacity of 6 million gallons and is pumped directly into the distribution system. A portion of the water received from Tallah pumping station is directly boosted to the distribution network by a Line booster pump installed in the pump house. The distribution system serves the drinking water needs for about 336,000 people, comprising for the population in the command area.
Energy Consumption Status - A Trail Based Measurement and observations
The study for energy consumption status was based on the different measurements conducted at RSM square BPS (Refer to Table No.1). Average water intake at RSM Square BPS from Tallah pumping station, as per Kolkata Municipal Corporation (KMC) data, is 29.3MG/Day, where as the quantity pumped out from the BPS based on the actual measurements carried out is 27MG/Day. Thus, 2.3MG/Day (i.e. 7.85% of the water pumped out from Tallah to RSM Square BPS) becomes Unaccounted For Water (UFW) even before being received at RSM Sq. BPS.
Table No.1 Details of the Measurements at RSM BPS
| Avg. Water Received from Tallah/Day | 133,198 m3 |
| Avg. Water Pumped Per Day | 122,852 m3 |
| Avg. Daily Pumping kWh Metered | 10,486 kWh |
| Avg. Max HT Power During Trails (6) | 1567 kW |
| Avg. Daily Pumping Energy Bill (3.3/Ut.) | Rs. 34,603 |
| Specific Energy Consumption | 0.085 kWhr/m3 |
| Avg. Water Pumped/Sec By 2 Pumps | 2225 LPS |
| Total BkW of Pumps | 10 @Hd mwc |
| Total Power Input to Motors Reqd. @ Motor Eff 92% | 368kW-400 kW |
| Avg. Water Pumped/Sec By 2 Pumps | 4900 LPS or 25 @Hd mwc |
| Total BkW of Pumps | 1567 kW |
| Total Power Input to Motor Reqd. @ Motor Eff 92% | 1704 kW |
| Max. Dem. (Sum of Motor KWs Max) | 2205 kW |
The average daily water quantity pumped out from the RSM Square BPS, based on the site trial measurements, was 122,852.5 m³ or 27.02 MG.
The population of the command area of the booster station as per the 2001 census is 335,763. The study indicates that the current quantity of water being pumped out from the RSM Square BPS is 366 liters per capita per day (LPCD). This is 37% above the average figure for KMC command area of 265 LPCD.
Such a high quantity of water pumped is attributed to the high rated head pumps installed at the station. Since the actual head at which the pumps operate is much lower than the rated head of 40m, the pumps are forced to operate beyond the maximum flow rate on the pump performance curve, where the pump efficiency is very low.
The station's operation is driven by water supply and as a result the pumps deliver a much higher quantity of water into the distribution system than it needs and can use. All of this excess water pumped into the system drains out as water loss.
The data provided by KMC regarding the population and connections in the command area shows that there are 1561 connections of various ferrule sizes. The estimated total water delivered by these connections, based on the ferrule sizes and duration of water supply, adds up to 41,212 m³. This is 33.5% of the total quantity of water pumped (i.e. 122,852.2 m³). Thus, 66.5% of the water pumped becomes UFW. This includes the water provided to stand-posts and fire services, although it does not include water lost through leakage in the pipelines or wasted at the consumer end in taps. This is a criminally large wastage, and moreover, it makes KMC absorb unnecessary energy costs and incur other expenses.
The average daily energy consumption at the station is 10,485.8 kWh at an average MD of 1567 kW. Considering the energy cost and overhead costs reported by KMC, the value addition to the water at RSM Sq. is Rs 0.38/ KL of water pumped out.
Energy Efficiency Improvement Opportunities at RSM Square BPS
Solution 1: Zero Investment Solutions
The Study reveals that the RSM Square BPS has been pumping 366 LPCD (38% more water than the city average) and a lot of this water (up to 66.5%) is unaccounted for. This situation can be improved upon by either reducing the number of operating pumps or by reducing the number of pump operating hours. Cutting down the pump running hours is not a practical solution, as the running hours must be in accordance with the water consumption pattern in the command area. Reducing the number of operating pumps, on the other hand, is feasible provided that the water supply is maintained in accordance with the city average. Once the flow is cut down to the city average the energy bill of the station will be substantially reduced as will the UFW in the distribution network.
This is therefore a Zero Investment Solution to Save Energy. It will help to bring down the energy bill by approximately 33% (i.e. by 3460 kWh per day) and reduce CO2 emissions by 1561 tonnes per year. Such a savings amounts to Rs 4,160,000 annually without any new investment in pumping station.
Solution 2: Revamp and Replacement Solutions
The capital investment required for this type of solution has been estimated on the basis of market indicators and is explained in the table below.
Statistics for the Revamp and Replacement Solutions
The population of the command area of the booster station as per the 2001 census is 335,763. The study indicates that the current quantity of water being pumped out from the RSM Square BPS is 366 liters per capita per day (LPCD). This is 37% above the average figure for KMC command area of 265 LPCD.
Such a high quantity of water pumped is attributed to the high rated head pumps installed at the station. Since the actual head at which the pumps operate is much lower than the rated head of 40m, the pumps are forced to operate beyond the maximum flow rate on the pump performance curve, where the pump efficiency is very low.
The station's operation is driven by water supply and as a result the pumps deliver a much higher quantity of water into the distribution system than it needs and can use. All of this excess water pumped into the system drains out as water loss.
The data provided by KMC regarding the population and connections in the command area shows that there are 1561 connections of various ferrule sizes. The estimated total water delivered by these connections, based on the ferrule sizes and duration of water supply, adds up to 41,212 m³. This is 33.5% of the total quantity of water pumped (i.e. 122,852.2 m³). Thus, 66.5% of the water pumped becomes UFW. This includes the water provided to stand-posts and fire services, although it does not include water lost through leakage in the pipelines or wasted at the consumer end in taps. This is a criminally large wastage, and moreover, it makes KMC absorb unnecessary energy costs and incur other expenses.
The average daily energy consumption at the station is 10,485.8 kWh at an average MD of 1567 kW. Considering the energy cost and overhead costs reported by KMC, the value addition to the water at RSM Sq. is Rs 0.38/ KL of water pumped out.
Energy Efficiency Improvement Opportunities at RSM Square BPS
Solution 1: Zero Investment Solutions
The Study reveals that the RSM Square BPS has been pumping 366 LPCD (38% more water than the city average) and a lot of this water (up to 66.5%) is unaccounted for. This situation can be improved upon by either reducing the number of operating pumps or by reducing the number of pump operating hours. Cutting down the pump running hours is not a practical solution, as the running hours must be in accordance with the water consumption pattern in the command area. Reducing the number of operating pumps, on the other hand, is feasible provided that the water supply is maintained in accordance with the city average. Once the flow is cut down to the city average the energy bill of the station will be substantially reduced as will the UFW in the distribution network.
This is therefore a Zero Investment Solution to Save Energy. It will help to bring down the energy bill by approximately 33% (i.e. by 3460 kWh per day) and reduce CO2 emissions by 1561 tonnes per year. Such a savings amounts to Rs 4,160,000 annually without any new investment in pumping station.
Solution 2: Revamp and Replacement Solutions
The capital investment required for this type of solution has been estimated on the basis of market indicators and is explained in the table below.
Statistics for the Revamp and Replacement Solutions
| Sl. No. | Items | Using all new 370 kW Motors and Pumps | Using 5 Nos existing and 1 no. new 370 kW motors and Pumps |
| 1. | Pumps Motors & Accessories | 540,000 | 340,000 |
| 2. | Station Piping Modifications & new values | 2,667,000 | 2,667,000 |
| 3. | Misc. Items & Labor | 235,000 | 235,000 |
| 4. | Contingency Buffer | 698,000 | 698,000 |
| 5. | Total Cost | 9,000,000 | 7,000,000 |
| 6. | Cost Recovery from the Residual Utility Value of the replaced machinery | 1,000,000 | 500,000 |
| 7. | Net Investment | 8,000,000 | 6,500,000 |
| 8. | Energy Bill Saving Opportunity | 3,990,920 | 3,990,920 |
| 9. | Saving in kWh/year | 941,193 | 941,193 |
| 10. | eCO2 Reduction/Year | 1163 tonnes | 1163 tonnes |
| 11. | Simple Payback Period | 2 years | 1.6 years |
Implementation of Audit Results
A meeting was organized at RSM Sq. BPS on April 23, 2003. ICLEI officials and Mr. Ramesh Juvekar, Consultant met Mr. Roy Choudhwary, Chief Engineer (Water Supply) and other municipal officials to discuss the implementation of the audit results. The following actions were agreed to in principle and will be implemented on a prioritized basis: (1) Operate a lesser number of pumps in-line as recommended; (2) Ascertain the actual number of pumps (to do so KMC will carry out an experiment); (3) Power Factor (PF) Improvement: KMC shall install and maintain capacitors so as to improve the average PF from 0.81 to 0.95, saving the KMC approximately Rs 38,000 /month.
A meeting was organized at RSM Sq. BPS on April 23, 2003. ICLEI officials and Mr. Ramesh Juvekar, Consultant met Mr. Roy Choudhwary, Chief Engineer (Water Supply) and other municipal officials to discuss the implementation of the audit results. The following actions were agreed to in principle and will be implemented on a prioritized basis: (1) Operate a lesser number of pumps in-line as recommended; (2) Ascertain the actual number of pumps (to do so KMC will carry out an experiment); (3) Power Factor (PF) Improvement: KMC shall install and maintain capacitors so as to improve the average PF from 0.81 to 0.95, saving the KMC approximately Rs 38,000 /month.
