Hydraulic Modeling and System Optimization

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1 DRINKING WATER ENERGY MANAGEMENT WORKSHOP SERIES TAKING ENERGY IMPROVEMENTS TO THE NEXT LEVEL: Hydraulic Modeling and System Optimization Steven Jones, M.S., P.E. September 4, 2013

3 What is a Water System Hydraulic Model? A digital (virtual) representation of a water distribution system in computer software that simulates hydraulic and water quality behavior within the pressurized pipe network.

4 Hydraulic model components: Pipes Pipe Junctions (Nodes) Pumps Valves (PRVs, etc.) Storage Tanks Reservoirs

5 Tank Reservoir Pump Pipe Valve Node

6 Data needed for pipes: Diameter Length Roughness (based on material and age)

7 Data needed for nodes: Elevation Water Demand

8 Data needed for valves: Type Position (open/closed) Setting (pressure, flow)

9 Data needed for pumps: Pump Curve Power Data Status (open/closed)

10 Data needed for wells: Pump Curve Power Diameter Pump Depth Ground water level during pumping

11 Data needed for tanks: Dimensions (Volume) Overflow elevation Floor drain elevation Water surface elevation

12 Data needed for reservoirs: Water surface elevation

13 Hydraulic computer models utilize userspecified input parameters to calculate: The water flow direction and flow rate in each pipe Operating pressure at each node Elevation of the water in each tank Concentration of a chemical or compound throughout the network Power used at each pump

14 STEADY-STATE vs. EXTENDED PERIOD

15 Water Distribution System Modeling Steady-State Represents a snapshot in time used to determine system behavior under static conditions Extended-Period Represents system behavior over a period of time used to model tanks filling and draining, pressures and flows rates changing throughout the system in response to varying demands

19 Control Settings PRV settings Booster settings Tank level controls

20 Extended-Period Water Model

21 Level (feet) Extended-Period Water Model TANK LEVEL SCADA System Model :00 AM 4:00 AM 8:00 AM 12:00 PM 4:00 PM 8:00 PM 12:00 AM

22 Flow (gpm) Extended-Period Water Model Well Flow SCADA Systeml Model :00 AM 4:00 AM 8:00 AM 12:00 PM 4:00 PM 8:00 PM 12:00 AM

23 WATER SYSTEM OPTIMIZATION

24 Energy consumption in most Water systems could be reduced by at least 25 percent through cost-effective efficiency actions - Alliance to Save Energy

25 Pumping water is often the largest share of a public entity s energy costs.

26 Much of the focus to date has been on improving equipment efficiencies, which is only a small portion of the potential energy savings in water systems. We have found many systems have significant opportunities to improve the efficiency of how a water system is operated overall.

27 In addition to energy inefficiencies, we have found many drinking water systems have inefficiencies in: Design Operation Performance Water Quality Water Use

29 Common Untapped Water System Performance and Energy Efficiency Measures Use an extended period model to better understand how the system operates Understand how control settings affect system efficiency More efficient use of equalization storage Meet peak demand without over-using sources Detect and prevent pumping in circles

30 Common Untapped Water System Performance and Energy Efficiency Measures (continued) Understand that system over-design can hurt efficiency Efficient vs. inefficient system layouts Use lowest cost water first Improve pressure management Detect inefficient pumps and motors Use the best electricity rate schedule for the application

31 Common Untapped Water System Performance and Energy Efficiency Measures (continued) Detect and repair water leaks Understand that poor maintenance and aging infrastructure robs the system of efficiency Identify and resolve water quality issues Understand how metering and rate schedules affect water use Understand how water conservation measures affect performance and efficiency

32 Better Understand Your System with an Extended Period Model See where water goes, how pressure fluctuates, velocity changes, pumps turning on and off, and tanks emptying and filling Understand the consequences of control and setting changes A tool to help operators, engineers, and managers understand each other

33 Better Understand Your System with an Extended Period Model System inventory and mapping Operator training and system operation guide Emergency response and trouble shooting tool Customer support

34 Control Settings PRV settings Booster settings Tank level controls

35 Efficient use of Storage Use equalization storage to meet peak demands instead of using sources Use storage as a battery pump water to the storage tank using an off peak electricity rate Identify where emergency and fire suppression storage levels are in tanks At the appropriate time, empty space in the tank can be as important as a full tank

37 Level Fluctuation at a Tank

38 FLOW (gpm) 12:00:00 AM 10:00:00 PM 8:00:00 PM 6:00:00 PM 4:00:00 PM 2:00:00 PM 12:00:00 PM 10:00:00 AM 8:00:00 AM 6:00:00 AM 4:00:00 AM 2:00:00 AM 12:00:00 AM Demand Flow Source Flow 60,000 50,000 Peak Instantaneous = 49,500 gpm 40,000 Peak Day Average = 32,500 gpm 30,000 20,000 10,000 Total Peak Day Volume = 46.8 MG Volume above Peak Day = 6.9 MG Volume from Storage = TIME

39 FLOW (gpm) PEAK MONTH SOURCE FLOWS DAY

42 FLOW (gpm) Keep Sources Constant It is generally more expensive to meet peak demand with sources Keep sources constant at highest operating efficiency Use flow control valves on wholesale connections to maximize the use of equalization storage and avoid peaking charges PEAK MONTH SOURCE FLOWS DAY

43 Eliminate Re-pumping of Water Use a water model to predict how much water should be pumped Use the model to trace where the pumped water is going to see if water is being re-pumped Determine if water is recirculating or leaking within the pump station through a PRV, relief valve, or surge protection device

44 Overdesign can hurt efficiency A water model allows you to better visualize how a design will meet project and system wide goals Helps to refine the design criteria for increased efficiency Oversized pump stations are not energy efficient Oversized pipelines and storage tanks can have slow recirculation, increasing water quality issues Design to accommodate increasing demand without sacrificing efficiency

45 Efficient Pump Station Design

46 Inefficient System Layout Unusable equalization storage because of tank location or elevation Inadequate transmission capacity Unnecessary relief of source water pressure Too much source and storage in the upper pressure zone with a majority of the demand in the lower pressure zone

47 Use Lowest Cost Water First Determine the total unit cost of using each source Know the limitations of each source (water rights, capacity, water quality) Facility Name Pumping Capacity (gpm) Pumping Cost (cost per ac-ft) Well A 1,000 $22.04 Booster #1 3,000 $36.09 Well B 3,000 $42.34 Pump Station 1,400 $45.71 Well C 1,600 $72.31 Well D 1,500 $129.85

48 Use Lowest Cost Water First Determine the total unit cost of using each source Know the limitations of each source (water rights, capacity, water quality) Understand the additional cost of using more than one source or pump station at once. Have prioritized source operation plans that maximize the use of lower cost water

49 Use Lowest Cost Water First Automate the prioritized operation plans as much as possible Use proper PRV settings and control settings that don t allow high cost water to be used over lower cost water Keep higher cost water where it is needed Maximize the use of lower cost water in the areas of the system where it can be used

50 Trace Movement of Water

51 Improve Pressure Management Higher pressures increase the potential for water loss, system failures and higher water use

52 Improve Pressure Management Higher pressures increase the potential for water loss, system failures and higher water use Identify whether a low pressure is caused by elevation or high velocity Identify large pressure fluctuations (large pressure fluctuations = inefficiencies Identify the cause of high velocities (inadequate transmission capacity, system imbalance)

53 Visualize Pressure and Velocity Results

54 Pressure Fluctuation at a Connection

55 Inefficient Pumps and Motors Use a water model to predict how much energy pumps should be using Track the performance and energy use of pumps and motors over time

56 Use the Cheapest Rate Schedule Understand the electricity rate schedules available Use the water model to identify which rate options and system operation schedules are the most feasible Use the water model to calculate electricity costs using the possible rate options and operation schedules and select the best rate schedule

57 Eliminate Water Loss Use the model to develop the most efficient flushing program Determine how much water loss the system has Use pressure tests, SCADA and meter data during the lowest demand period to calibrate a water leakage model Model actual metered demand data and source flows during the lowest demand period Use emitter coefficients to predict water leakage hot spots in the system

58 Poor Maintenance Tuberculation in old cast iron pipe can dramatically decrease capacity and increase head loss

59 Poor Maintenance Tuberculation in old cast iron pipe can dramatically decrease capacity and increase head loss Leaks in old pipes, valves, and facilities Worn pumps and motors Malfunctioning PRVs and relief valves Malfunctioning SCADA and controls

60 Water Quality Issues A water model can simulate water quality in your system Understand the fate of chlorine and the concentration of fluoride in your system and increase efficiency Help you understand water age and contaminant concentration Track the location of a contaminant source Predict how source mixing can improve water quality

61 Understanding Water Quality Patterns

62 Common Barriers to Improving Drinking Water System Efficiency Lack of Awareness. People will not make changes towards efficiency unless they are aware of the cost-benefit arguments for doing so. This is especially true in the case of applying energy efficiency to water supply, since those who operate day to day in the water sector are not accustomed to focusing on energy.

63 Common Barriers to Improving Drinking Water System Efficiency Risk. Deviating from the usual routine is associated with risk, real or perceived, such as added burden on staff or financial risk. Fear of change has a rational basis and breaking through it requires that the fears be addressed and that the benefits of change clearly outweigh risks.

64 Common Barriers to Improving Drinking Water System Efficiency Change May Imply a Problem with the Status Quo. It is not uncommon for staff to be resistant to new ideas and procedures due to a feeling that suggestions for change imply criticism of their performance and ability.

65 Common Barriers to Improving Drinking Water System Efficiency Cost. Understanding energy and water inefficiency in a water system costs money that many find hard to budget for. How can a water system afford not to get rid of inefficiency? Many untapped water system efficiency measures cost little if anything to implement and the payback is ongoing. Measures that require upfront capital costs generally have short payback periods.

66 IN SUMMARY 1. 1 Water systems have significant untapped efficiency improvement potential 2. We have identified solutions to many common inefficiencies found in water systems 3. An extended period water model is a valuable tool to improve system performance and energy efficiency

Hydraulic Modeling, PUDs & Managing Water System Growth

Hydraulic Modeling, PUDs & Managing Water System Growth American Water Resources Association Intermountain Section October 9, 2013 Utah Division of Drinking Water Ying-Ying Macauley Presentation Topics