Paper Code: ISC/2014/TP/62/2014
Energy Efficiency in Urban Water Supplies
Need for Web Interactive Tool
G Rudra Narsimha Rao1 E Nand Gopal K V Sharma
Industrial Energy Division Industrial Energy Division Centre for Energy Studies The Energy and Resources Institute
(TERI)
The Energy and Resources Institute
(TERI)
Jawaharlal Nehru Technical
University (JNTU) Bangalore, India New Delhi, India Hyderabad, India
[email protected] [email protected] [email protected]
1 Corresponding Author
Abstract – In India the share of urban water utilities’
electrical energy consumption is over 5% of national
electricity production. Energy cost is usually between
50 to 60% of the total operating cost of an urban water
supply system. In urban water supply systems 90% of
this electrical energy is consumed by pumps. The major
component of the life cycle cost (LCC) of pumps is
related to the energy spent in pumping, the remaining
being related to the purchase and maintenance of the
equipment. A small improvement in pumping efficiency
would yield significant reduction in energy
consumption, which would in turn lead to reduction of
carbon emissions to the atmosphere. The data gathered
from urban water pumping stations in various cities
and towns, where energy conservation studies were
conducted in India have been used in the analysis. The
flow rate and quantity of water pumped, the number of
pumps in use, the duration of operation, motor
rewinding history was recorded for each station.
Portable instruments were used for measuring actual
parameters. This paper encapsulates data compilation
and various energy related issues of different urban
water supply system in India. To assist the water utility
staff a web based interactive tool has been developed
for identification of energy cost saving opportunities.
The implications due to the use of such an online tool
and its benefits are deliberated in the paper.
Keywords — Energy efficiency, Urban water supply, Cost
effective solution, Web interactive tool
I INTRODUCTION
In India the share of the urban water utilities’ electrical
energy consumption is over 5% of the national electricity
production. Energy cost is usually between 50 to 60% of
the total operating cost of an urban water supply system. In
urban water supply systems 90% of this electrical energy is
consumed by pumps. Pumping energy cost forms an
important part of the operational cost of water distribution
systems worldwide. Upgrading motors and pumps with
energy efficient ones and properly adjusting them for
system requirement often allow significant energy savings
[1]. Changing the pumping operational procedures is a
very effective way for optimizing its energy consumption
and it does not need any additional investment, the
reduction in energy cost occurs immediately. Efforts to
increase energy efficiency can reduce electrical
consumption for pumping by as much as 5% – 25%, and
sometimes even greater savings are realized [2].
The major component of the life cycle cost (LCC) of
pumps is related to the energy spent in pumping, the
remaining being related to the purchase and maintenance
of the equipment. The issues pertaining to India is different
than developed countries in this particular area. A huge
sum of town municipality budget amount goes for paying
electrical utility bills The cost savings in water supply can
lead to effective quality services (such as education, health,
water and sanitation) to the local communities. One of the
essential elements for optimizing energy cost of urban
utilities is data monitoring and analysis. Understanding of
present tariffs and operational improvements itself results
into a significant cost savings. A small improvement in
pumping efficiency would yield significant reduction in
energy consumption, which would in turn lead to reduction
of carbon emissions to the atmosphere.
In recent years, municipalities in global scenario are
finding it challenging to supply potable quality piped
drinking water due to a phenomenal growth in the urban
population over past five decades. The issues affecting the
water sector include disparity in water supply across
regions, depletion of ground water and undercapitalized
municipalities. The disruption in the monsoon rainfall
pattern and rising energy tariffs has also created problems
in meeting additional water requirement. Municipalities are
spending large portions (40 - 60% of budget) of their
revenues on purchasing energy for providing public
services such as street lighting and water supply [3].
According to a recent Electric Power Survey, the Public
Water Works in India consumes more than 12000 MUs
and Public Lighting consumes 5000 MUs of electricity.
Theoretical studies and practical implementation of
optimal pump scheduling in various types of supply
systems suggest that 10 % of the annual expenditure on
energy and related costs may be saved if proper
optimization methods are used [4]. The objectives is to
analysis the water utility system, and simulate several
scheduling scenarios with optimized pumps in order to
minimize the expenditure related to energy consumption,
based on the demand patterns and associated energy tariffs.
Paper Code: ISC/2014/TP/62/2014
At the same time, there is also a need for creation of
awareness among the operating staff of water utilities on
energy issues, steps for evaluation of their operating
system from energy performance view point, identification
of energy efficiency opportunities and induction of energy
management approaches for integrating better standards
and practices in everyday operation of water utilities.
II MUNICIPAL WATER SUPPLY SYSTEMS
The basic classification of water supply is based on type
of source - ground water and surface water. Ground water
sources (such as wells) indicate that the water is below
ground level or the earth’s surface. Depending on the depth
of the well, a pump may be able to transport the water
directly to the water treatment facility; or else one or more
pumps are needed in series to move water to the treatment
location. The treated water can be pumped to water storage
facilities or pumped directly into the distribution system.
There are two basic types of water supply systems
which are used to create water pressure within the
distribution system are gravity feed system and pumping
pressure system. Difference in elevation between the water
treatment plant and the municipal area to be served, the
water may flow by gravity through the distribution
systems, or there may be the need for another pumping
station. Sometimes a combination of gravity flow and one
or more pumping stations could be suitable and
economical to transport water from the source point to all
the water demand points on the distribution system [5].
The fundamental correlation between water and energy
is not widely understood or adequately exploited through
coordinated holistic efficiency approaches. The water-
energy relationship is based on the reality that treating
water for human consumption and pumping treated water
to the consumer is an extremely energy intensive process.
Every single litre of water that passes through a system
represents a substantial energy cost. A review of demand
management techniques applicable for developing
countries can be found in Vairavamoorthy & Mansoor [6].
One of the energy efficient methods to meet municipal
water demand and flow control, particularly for systems
where static head is a high proportion of the total head, is
to install two or more pumps and operate them in parallel.
A variation in flow rate is achieved by switching on and
off additional pumps to meet the demand. The combined
pump curve is obtained by adding the flow rates at a
specific head. The system curve is usually not affected by
the number of pumps that are running. It is also apparent
that the flow rate with two pumps running is not double
that of a single pump. If the system head was only static,
then the flow rate would be proportional to the number of
pumps operating. Care must be taken when running pumps
in parallel to ensure that the operating point of the pump is
controlled within the region deemed as acceptable by the
manufacturer [7].
III METHODOLOGY
The data gathered from municipal water pumping
stations in various cities and towns, where energy
conservation studies were conducted in India, have been
used in the analysis [1]. The flow rate and quantity of
water pumped, the number of pumps in use, the duration of
operation, motor rewinding history was recorded for each
station. The actual flow rate of water, inlet and outlet
pressures at the pump, power consumed at each installation
were measured using the following instruments:
• Portable load manager to monitor and log the
transformer parameters (Voltage, current, power factor,
kW, kVA, kVAr, Hz, kWh);
• Clamp on electrical power analyzers to measure and
log the individual motor parameters (Voltage, current,
power factor, kW, kVA, kVAr, Hz, kWh);
• Ultrasonic water flow meter to measure the velocity
and flow rate of water at the pump and in piping system;
• Digital pressure sensor to measure the delivery head
of the pumps.
Motor characteristics curves for various ratings
collected from the manufacturers and used during the
analysis. The above measurements and analysis carried out
for over 433 pumps of different ratings (connected motor
to pumps 11 kW to 2600 kW) installed across 98 pumping
stations in five states in India are given in Table 1.
Table 1 Details of pumping stations used for analysis
City / State
No. of
pumping
stations
No. of
pumps
(Operation)
Annual Energy
Consumption,
million kWh
Bangalore 9 67 179
Delhi 7 49 129
Pune 6 38 76.7
Vishakhapatnam 4 13 48.7
Andhra Pradesh
(2
Municipalities)
5 16 3.5
Karnataka
(11
Municipalities)
26 46 62.4
Tamil Nadu
(25
Municipalities)
41 204 41.7
It was observed that water scarcity is significant in
many locations and in some cases it is seasonal in nature.
Most of the water pumping stations was not equipped with
measuring devices to know the actual performance of the
systems.
IV DATA ANALYSIS AND ENERGY SAVING
POTENTIAL
A selection 16 municipality, based on population
coverage to suit Indian towns has been done via sampling.
Analysis of these16 towns/cities is presented in this
section. The collected data was analyzed based on the
water availability at the source and the present installed
capacity of the pumping stations. The comparison of the
per capita figure against the all India norms of 135 LPCD
(litres per person per day) water supplies reveals the
deviation from this norm at these municipal towns.
As seen from the above chart the difference in the
amount of water received varies largely from town to
town, and 75% of the towns receive less than the all India
Paper Code: ISC/2014/TP/62/2014
norms fixed by the government. A major reason for this is
the non-availability of water at the source. It is also not
unusual that the schemes with low installed capacity
integrate bore-well water at numerous locations within the
municipal vicinity area. In various cases these bore-wells
are hand operated.
Figure 1 Classification on the basis of per capita water
supply
The comprehensive detailed study revealed that
significant potential exists in municipal water pumping
installations in terms of improving the energy efficiency.
The details of energy and cost savings identified, as a
result of the energy audit is classified in terms of the
percentage saving potential, are given in figure 2.
Figure 2 Percentage energy saving potential
The costs that can be saved by implementing energy
saving measures can be utilized for the following
initiatives:
Improved water quality deliverables to the end
users
Better maintenance and house-keeping practices
Advanced metering and monitoring facilities
Creating awareness programmes on energy
efficiency in other/neighboring municipalities
Some of the additional benefits could include
Improved quality of water
Better hygienic conditions
Improved accounting of water
Awareness among municipal staff on energy
efficiency issues which leads to better
operations
The energy that is saved at the user end directly has an
impact at the generation end. If 100 units of fuel input is
available (say coal based plant) and considering the typical
efficiency available for intermediately systems / equipment
like transmission & distribution, motor, pump, throttled
valve & pipe losses etc., the units finally available at end
user such as a water utility would be only 9.6 units after
accounting for built-in efficiencies of the equipment in
between systems (shown in Figure 2.13) i.e., 100 units of
fuel input would finally reaches as 9.6 units at motor
terminal (100x0.096) due to several system efficiencies up
to user point (0.3 x 0.85 x 0.9 x 0.75 x 0.7 x 0.8) of various
systems. A typical power supply system where the water
pumping installation is the final consumer is shown in
figure 3.
For every unit saved at the pumping station, generation
can be reduced by almost 9.6 times since there are several
intermediary players for the power to reach the end users.
Generally for every unit produced in coal based power
plants reduces the emission by almost 0.78 kilograms [7].
The figure depends on the efficiency of coal based power
plants and the station heat rates.
As per the Central Electricity Authority report on 17th
Electric Power Survey, the annual energy consumption of
water supply systems is 12,000 million units. A 10%
reduction in energy consumption by incorporating energy
efficiency measures will amount to 1,200 million units
reduction in energy at the user end thereby yielding 11,520
million units reduction potential at the generation end. The
GHG emission reduction potential works out to 9.33
million MTCO2e annually.
V WEB INTERACTIVE MONITORING TOOL
A monitoring tool has been developed to capture basic
infrastructure details of municipal water pumping systems
(such as electrical system and its prevailed tariff structure,
pumps and its configuration, specifications etc.). These
details can be entered along with registration. A back end
data base storage has been created which captures all the
entered monthly details (billing details, operating hours,
number of pumps in use etc.). A comparative analysis is
carried out based on operational data versus design (or)
allocated data applicable to a particular pumping station.
The results are displayed in terms of graphical
representation which can be viewed and understood by the
operating staff (skilled or unskilled). Depending upon the
available instrumentation / information pumping station
level data can be entered. It can be analyzed on a monthly
and daily basis.
The tool is a web interactive mode of operation with
availability of expert services which is optional, where
municipal utility staff can pose questions to the experts
based on the data furnished. The technical expert team also
can view the furnished data and provide free advisory
services through mail (or phone). This will help the
municipal staff to take necessary steps to enhance the
pumping system operating efficiency. Some of the screen
shots of online interactive tool are furnished in figure 4.
Paper Code: ISC/2014/TP/62/2014
Figure 3 Typical supply
Ratio 1 : 0.25 Ratio 1 : 4.5
ɳ=
80% pipe
Input Fuel 100 units
ɳ= 30%
power plant
ɳ= 85%
T&D
Drive system (from meter to
input shaft of machine)
ɳ= 90%
motor
Applications
ɳ=
75% pump
ɳ=
70% valve
Water pumping system with proper design
Utility system up to water pumping installation
Interest of boundaries to public, which also cares about cost of generation utility to water pumping
system
End use (flow)
Thermal Power Plant
Transmission Distribution Utility Meter
Motor
Pump
Main
Pipeline
Valves
Transmission Piping
Paper Code: ISC/2014/TP/62/2014
Figure 4 Snap-shot of web interactive tool (seven shots)
Energy conservation measures such as utilization of
contract demand (including penalty), power factor
management, operation of pumps (with respective to
piping networks) and drop in pumps operating efficiency
are analyzed for corrective action using the web based
monitoring tool. The details of computer aids used in
developing the web based interactive tool are given in table
2.
Table 2 computer aids are used in upgraded version
Language C# .Net
Web UI ASP.Net
IDE Visual Studio 2012
Framework .Net 4.5
Database MySQL 5.0
VI RESULT AND DISCUSION
A majority of the municipalities in India are not
familiar with new concepts and technologies available in
the market, due to lack of education and training.
Municipalities should make it as part of their work culture
to educate ground-level as well as supervisory staff on
energy, water and technologies that are available to
improve efficiency. Inefficiencies should be pointed out
and figures should be converted into their rupee
equivalents, and given in terms of hour, day, and year.
Educating the staff on these figures will result in cost-
effective initiatives emerging from the ground level staff
members who operate the system.
Most municipal personnel follow a routine working
pattern rather than going a step further. The routine
working pattern can be attributed to lack of individual
commitment, and most importantly and absence of
Paper Code: ISC/2014/TP/62/2014
motivation from seniors. A human resources team should
be formed for these assignments, whereby the working
personnel become aware of the bottlenecks and take
necessary actions towards improving energy efficiency.
Moreover, a back-up support from the top-level
management can bring about miraculous results towards
achieving higher efficiency.
Time series data pertaining to energy consumption,
cost of energy inputs and other related data like quantity
water pumped, which has a bearing on energy
consumption, should be collected. Historical data available
with the utilities for major equipment including billing
systems needs to be studied. Information on inventory of
the electrical / mechanical equipment installed and its
operating parameters (like hours of operation of pumps,
actual load in kW etc.) should be collected. These data
should be compared with the design/operating values and
margins for improvement can be found out.
The online web interactive analytical tool is a step
forward towards addressing municipal staff awareness /
training / skill development for energy cost savings of their
respective municipal water system. Energy efficiency
studies have established that energy costs account for 40 to
60% of the operating expenses for supplying water. By
becoming energy efficient, each municipal water system
can reap a minimum energy savings of 25 to 40%. This
translates to an energy savings of at least 3000 MUs (based
on the data that public water works in India consumes
more than 12000 MUs), which means that one can avoid
the need for an additional capacity of 500 MW for the
Indian scenario.
The case studies presented below are from
Municipalities of two states from southern India: Andra
Pradesh and Karnataka. The case studies are broadly
divided into 3 categories:
Electrical systems and drives
Pumping system
Operational and other aspects
Details some of the case studies are presented in table 3.
Back Ground Energy
Conservation
Measure
Realisation
saving potential
Fine tuning of the existing contract demand to meet
the present loading conditions
Contract
demand of 1000
kVA
Minimum
billing demand
80%
Measured
instantaneous
CD 172 kVA
Reduction of
the contract
demand to 300
kVA
Surrendering
700 kVA
Demand
saving of 650
kVA
Amounting to
Rs. 15.21 lakhs
annually
Installation of capacitors to improve power factor (pf)
and reduce kVA demand
Average pf
0.83
Penalty Rs
4.32 lakh/yr
110 kVAr
bank installed
Install 125
kVAr
additional
Improve pf to
0.95
Demand
reduction by
101 kVA
Annual
demand saving
Rs 2.18 lakh
20 kVAr bank
not working
Annual
saving by pf Rs
4.32 lakh
Suitable sizing of booster pumps
2 centrifugal
pumps installed
for booster
8km from
reservoir
Rated 660 lps
@ 62m
Measured 670
lps @ 46m and
710 lps @ 46m
Operating
efficiency 61%
and 64%
Head
mismatch 16m
Replace with
710 lps @ 48m
pump
Overall
efficiency 80%
Reduction in
power 84 kW
7.3 lakh kWh
energy saving
Annual
saving Rs 25
lakh with
investment of
Rs 10 lakh
Modification in the existing piping network for
enhanced water flow
4 centrifugal
pumps in
parallel
Each Rated
15.86 MGD at
50 Hz
Drawing
14.23 MGD
15% deficit
Output
enhanced by
modifying
header system
Additional 1.4
MGD drawn
after
modification
Reduction in
specific energy
consumption by
8.6%
Annual
energy saving
5. Lakh kWh
Amounting to
Rs 20 lakh
Improving the main water flow distribution system
Detailed flow
pattern carried
out
Assess water
loss due to
leakage
37% leakage
Reducing the
leakage level <
10%
Annual
energy saving
5.3 lakh kWh
Amounting to
Rs 21 lakh
Cost of
implementation
Rs 2 lakh only
VII CONCLUSION
Energy costs are typically the highest or second highest
governable costs for water utility operations. Using new
developments in the area of pumps allows for initially
selecting a pump to match the expected performance
requirements and then maintain optimal performances
through periodic refurbishment. These measures realize
energy cost savings, it is not necessary that electrical
system part designed to suit local conditions (tariff
structures).
From the study it is clear that a tremendous energy
saving potential exists in these municipal water pumping
installations. One of the interventions needed is to train
and create awareness among the municipal utility staff
about the benefits of energy efficiency improvement. In
order to help and assist these staff with available
resources/information an online web interactive monitoring
tools has been developed. The tool will help in better
understanding of their municipal water system and changes
required for realizing energy cost saving opportunities time
to time. Municipalities can utilize the energy cost savings
accruable as a result of implementing energy efficiency
measures for any other important services like health,
education which are equally important in sustainable
development.
Paper Code: ISC/2014/TP/62/2014
ACKNOWLEDGEMENTS
The authors would like to acknowledge the support of
all water utilities for sharing the data and allowing us to
perform the study. Our sincere thanks to all who were
directly or indirectly involved in the study and analysis.
Finally we wish to acknowledge the support of all the
TERI team members who were involved in the detailed
study of all the water utilities in states of India and other
developing countries.
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