energy efficient water and wastewater plant design and operation · energy efficiency consideration...

Energy Efficient Water and Wastewater Plant Design and Operation

02 August 2017

ThonhoffConsulting

Engineers, Inc. (TCE)

Saleem Khan, P.E. CxA Bob Thonhoff, P.E.

Texas Energy Engineering Services, Inc. (TEESI Engineering)

(www.teesi.com)

Presented by:

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Energy Efficient Water & Wastewater Treatment Plant Design and Operation

Presented by: TEESI & TCE

SECO Facilities and InfrastructureEnergy Management Webinars

Indoor & Outdoor Lighting Retrofit Options Overview (7/20/2017 @ 2:00 PM)

Energy Accounting & Benchmarking (7/26/17 @ 2:00 PM)

ENERGY STAR Portfolio Manager Overview (7/27/17 @ 2:00 PM)

Preliminary Energy Assessments Overview (8/1/17 @ 2:00 PM)

Energy Efficiency Consideration for Water and Wastewater Systems

(8/2/17 @ 2:00 PM)

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Welcome

Housekeeping itemsPDF of presentationVideo recording of presentationPollingQuestions

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Introduction

State Energy Conservation Office (SECO)Schools & Local Government Program

Program provides Free Energy Assessments, training, and Technical AssistancePreliminary Energy Assessment (PEA)Energy Efficiency Consideration for Water & Waste Water Treatment Plant

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Energy Audit

One of the first steps involved in energy cost control of facilitiesEnergy Audit or Survey consists of:Examination of how a facility uses energyDetermining cost of energy for the facilityRecommending operational changes (low/no cost measures)Recommendation for cost effective equipment upgradesReport development

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Energy Audit Basic TypesPreliminary Energy Assessment (PEA)Preliminary Energy Audit/AnalysisInitial Energy Audit or SurveyWalkthrough Survey/Assessment

Detailed Energy Analysis (DEA)Comprehensive Energy Analysis (CEA)Investment Grade Audit (IGA)Utility Assessment Report (UAR)

ASHRAE categories (I,II,III)Not relevant to WWTP/WTP

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Poll Question:

Have you conducted any kind of energy audit at any of your facilities in the past

three (3) years?

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PEA Process Summary

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Establish Energy Performance Indices (WWTP)

Energy Use Index (EUI)Annual energy usage divided by average effluent flowkBtu/GPD/Year

Energy Cost Index (ECI)Annual energy cost divided by average effluent flow $/MGD/Year

Normalization Other factors influence EUI & ECI for WWTP

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Establish Energy Performance Indices (cont.)

16.7

7.5

4.9

3.3

0 5 10 15 20 25

WWTP B

WWTP D

WWTP C

WWTP A

EUI (kBtu/GPD/Yr)

Facility Energy Performance EUI (kBtu/GPD/Yr)

Energy Utilization Index Energy Cost Index

$394,771

$247,226

$131,406

$98,215

$0 $250,000 $500,000 $750,000

WWTP B

WWTP D

WWTP C

WWTP A

ECI ($/MGD/Yr)

Facility Cost Performance ECI ($/MGD/Yr)

EXAMPLE WWTP FACILITIES

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Utility Rate AnalysisAverage Utility Rates

Power Factor Analysis

FacilityElectric

ProviderElectricity

$/kWhHeating Fuel

ProviderFuel

$/MMBTU

Facility A W Provider $0.076 Y Provider $ 5.23

Facility B W Provider $0.079 Y Provider $ 5.00

Facility C X Provider $0.105 Z Provider $ 7.21

Facility D X Provider $0.097 Z Provider $ 7.45

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Utility Rate Analysis (cont.)

Electrical DemandPeak power draw (kW)Demand Charges ($/kW)

Load Factor AnalysisConsistency of facility usage

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Facility Site Visits

Initial MeetingOperators, Engineers, Director of Maintenance, etc.Discuss Plant Operation & Concerns

Walkthrough of Facilities

Identify Energy Savings Measures

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General Maintenance and Operation Considerations

Low Cost/No Cost MeasuresRoutine MaintenanceEquipment SchedulingSet PointsOperational ProceduresGuidelines for Efficiency Levels of Future Equipment Purchases

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Energy Management (EM) Plan

EM Plan?

Review existing EM Plan

Assist in developing a more comprehensive plan

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Poll Question:

Do your facilities have an Energy Management Plan? If so, how often do you

review and revise it?

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ConsiderationsPremium Efficiency Pumps & MotorsVFDs or “Soft‐Start” to Pumping SystemsCompare Cost of Chemical to Cost of PowerControl Dissolved Oxygen LevelUtilize Off‐Peak Energy Demand PumpingEvaluate Pipe SizingUtilize Leak Sensing SystemsModify the System OperationsOther…

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Technical Assistance Examples

Thermal ScanningEquipment Inventory &

Visual Inspection

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Technical Assistance Examples (cont.)

Utility Meter MappingPlant Operation &Visual Inspection

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Typical UCRM’s and PaybacksWTP/WWTP Systems

WWTP related O&MMeasures 0 to 1 yearDissolved Oxygen Control 2 to 7 yearsHigh Efficiency Blowers 8 to 12 yearsVariable Speed Drives 8 to 15 yearsOptimize Aeration Design 5 to 10 yearsPower Factor Improvements 3 to 8 yearsSmart Meter Applications 5 to 8 yearsCity Mains Leak Sensing Technology 1 to 6 yearsWWTP Demand Response *

*Dependent on existing load profile and capital used for automation

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Case Study – City of San Marcos

(Lighting Retrofits, High Eff. Blower & Aeration Flow Control, Occupancy Sensors, HVAC Replacement, Energy Management Systems, Solar Thermal Pool Heating System, Water Conservation Measures)

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Case Study – City of Pharr

(DO Control, High Eff. Blowers, VFDs, Leak Sensing Technology)

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Case Study – New Braunfels Utilities

(Coarse to Fine Bubble Diffusion, DO Sensors, Variable Speed Blowers, City‐wide 5/8” Water Meter Change‐Out to Smart Meters)

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Water Pumping

Use Energy Efficient Pumps and Motors

Typical Maximum Efficient Pump: 80% Typical Maximum Efficient Motor: 94%

Typical Worst Case Pump: 60% Typical Worst Case Motor: 90%

Potential Energy Savings: approx. 15% of annual consumption

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ELEVATED TANK

WATER SOURCE

WTPPUMP

PUMP

ELEVATED TANK

ELEVATED TANK

PUMP

ELEVATED TANK

Water Pumping -Optimize Pressure Planes

Pump to lowest pressure plane firstEnergy cost: $15,000/MGD/year/100ft head

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Water Pumping –Off-Peak Energy Demand Pumping

Utilize Excess Elevated Storage Capacity During Energy Demand Time Period

Utilize Variable Frequency Drive Pumping

Energy Savings: 25% of cost of pumping during energy demand time period$4,000/MGD/Year

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Water Treatment

Utilize Energy Efficient Pumps & Motors

Utilize Variable Frequency Drive

Optimize Plant’s Hydraulic ProfileEnergy Savings:

approx. $1,500/MGD/Year/10 Ft. Head

Compare Cost of Chemical to Cost of Energy

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Wastewater PumpingUse Energy Efficient Pumps and Motors

Typical Maximum Efficient Pump: 70%Typical Maximum Efficient Motor: 90%

Typical Worst Case Pump: 40%Typical Worst Case Motor: 85%

Potential Energy Savings: approx. 10% of annual consumption

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Wastewater Pumping

Use Variable Frequency Drives on Large Horsepower (>50HP) Units to save Energy Demand Charges

Potential Energy Savings: 25% Pumping Cost During Demand Period $3,400/MGD/Year

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Wastewater Pumping

Design Gravity Flow Systems Wherever Possible

Potential Energy Savings: $10,000/MGD/Year/30 Ft. Head

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Wastewater TreatmentOptimize Hydraulic Profile

Optimize Aeration Design

Utilize Natural Treatment Processes

Compare Cost of Chemicals to Cost of Power

Control Dissolved Oxygen

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Wastewater Treatment –Optimize Hydraulic Profile

Pump Wastewater OncePotential Energy Savings: $3,000/MGD/Year/10ft Head

CLARIFICATIONDISINFECTION

AERATION

LIFT STATION

DISCHARGE

GRAVITY SEWER

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Wastewater Treatment –Optimize Aeration Design

Potential Energy Savings:approx. 50% of annual consumption

Transfer Rate(# O2/HP∙hr)

Coarse Air Bubble 1.5

Fine Air Bubble 3.3

Mechanical Aeration 3.9

Fine Air Bubble w/Full Floor Coverage & High Efficiency Blowers 6.6

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Coarse Bubble Aeration

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Fine Bubble Aeration

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Bubble Types

Fine Bubble Coarse Bubble

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Mechanical Aeration

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Wastewater Treatment –Utilize Natural Treatment Processes

Facultative LagoonsPotential Energy Savings: approx. 70% of annual consumption

Trickling FiltersPotential Energy Savings: approx. 65% of annual consumption

Anoxic Zones (For Denitrification)Potential Energy Savings: approx. 10% of annual consumption

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Wastewater Treatment –Control Dissolved Oxygen

TCEQ Criteria : 2.0 mg/l of D.O.Process Requirements : 0.5 – 1.0 mg/lGeneral Statement:“Anything over 1.0 mg/l is wasting power”Potential Energy Savings:$1,000/MGD/Year/mg/l D.O.

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Wastewater Treatment –Compare Cost of Chemicals to Cost

of Power

Example:

Ultraviolent Disinfection will become cost‐effective within a 7 year period when compared to chlorination / dechlorination

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Funding

State Energy Conservation Office (SECO)Texas LoanSTAR Program (low interest revolving loan)https://comptroller.texas.gov/programs/seco/funding/loanstar/

Texas Water Development Boardhttp://www.twdb.texas.gov/

US Department of Agriculturehttps://www.usda.gov/

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Questions?

Saleem Khan, P.E., CxATEESI Engineering

(512) [email protected]

www.teesi.com

Stephen RossState Energy Conservation Office (SECO)

Office: [email protected]

https://comptroller.texas.gov/programs/seco/

BobThonhoff, P.E.Thonhoff Consulting Engineers, Inc.

(512) [email protected]

www.tcetx.com

energy efficient water and wastewater plant design and operation · energy efficiency consideration...

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