Energy Efficiency and Process Optimization to Save Money
April 28, 2015 April 29, 2015 City of Surprise Town of Gilbert 11401 N. 136th Avenue 900 E. Juniper Avenue Surprise, AZ 85379 Gilbert, AZ 85234 Preface
• Welcome • Agenda • Speakers
2 Preface
• Welcome • State of the Industry • Agenda • Synergies with Electric Utilities • Speakers • Energy Billing and Demand Management • Energy Management Opportunities • Energy Management Program Development
3 Preface
• Welcome • Agenda 1400 E. Southern Avenue Suite 650 • Speakers Tempe, AZ 85282 (480) 436-7959
4 Preface
WATER REUSE • Welcome Prov iding sustainable solutions using technology and processes to max imize w ater resources and reduce • Agenda energy footprint • Speakers
5 Speakers
Eric Dole, PE Bryan Lisk, PE, CEM
Doug Kobrick, PE Curt Courter, PE
6 Thank You!
7 Housekeeping
• Please mute all phones • Refreshments • Restrooms • Q&A • PDHs
8 Energy Management “State of the Industry” Energy Management is more than “Energy Efficiency”
Energy Recovery Demand Management Alternative Energy Energy Procurement Nutrient Recovery Process Optimization “Beyond the Plant Fence Line”
• View energy in a broad context • More than plant optimization • Multiple synergies with other industries Goal of "Energy Neutrality”
• Becoming a common goal in wastewater industry. • View Energy Neutrality as more than “no purchased power bill”. Focus on Resource Recovery
• Electric Energy • Biofuels Biogas Utilization • Thermal Energy (Heat) • Kinetic Energy (Hydro Energy) • Nutrients
Nutrient Recovery Renewable Energy Systems Evolving Energy Markets and Regulations
Renewable Energy Portfolio Renewable Fuel Standards Low Carbon Fuel Standards Standards (RFS2) (State of California)
• Electric Utility Industry • Transportation Fuels, NG • Fuels (Transportation Fuels, • Renewable Energy Credits Pipeline NG, etc.) (RECS) – MWH of renewable • Renewable Identification • Credits issued by CO2 avoided energy generated Number (RIN) by low carbon fuels • State level • Pathways developed for biogas • Projects outside CA can • Nationwide generate credits
Electric Energy Fuels (i.e. RNG, biodiesel, biofuels, ethanol)
Driven by Climate Change, Energy Independence/Security Alternate Project Delivery
• Address payback risks Design Bid Build • Zero capital cost projects Leverage “savings” to move project Owner Performance • Procurement Contracting forward • Revenue Diversity Energy Project
Utility DSM 3rd Party Rebate Ownership Programs
Shared Savings Energy Management Master Planning
• Develop a plan to implement energy projects • Identify opportunities and integrate with CIP • Understand “whole plant impacts” • Flexibility for changing conditions and new technologies • Business case evaluations Synergies with Electric Utilities
• Demand Side Management • Renewable Portfolio Standards • Generator Capacity Credits • Load Curtailment • Energy Project Funding Synergies with Electric Utilities Utility Rebate Programs
Arizona Corporation Commission (ACC) SRP Rebate Program
Customers can receive up to $300,000/yr in rebates Most water-related projects would receive rebates under SRP’s Custom Business Solution Program. Custom Program Highlights: • An approved rebate application is required before initiating purchase or installation to qualify • Equipment rebates offered at $0.10/kWh savings up to 50% of project cost • Additional, optional technical services available for qualifying customers. SRP Rebate Program
Relevant Technical Services: • Preliminary Assessments (PA): • Pump Test – • $350/pump for preliminary efficiency test/recommendations • Active pumps over 25HP in non-HVAC applications would qualify • No limit on number of evaluated pumps • Energy Conservation Measure (ECM): • Large plants/pump stations may qualify; requires E-60 series price plan • Funded 100% up to $3,000 for initial, high level energy study on preselected systems / opportunities. SRP Rebate Program
Relevant Technical Services: • Technical Assessments (TA): • After a Preliminary Assessment is conducted, a Technical Assessment can be conducted as an investment grade evaluation of ECMs • Co-funded at 50% by SRP up to $10,000 initially. • Customer’s share is reimbursed if some measures are implemented. SRP Rebate Program
Example: . WTP receives PA to evaluate ECMs; SRP pays $3,000 @ no cost to the Customer . Some ECMs have good economics, need further study. Assume TA costs $28,000; SRP pays $10,000, Customer pays $18,000 . ECM saves 300,000 kWh/yr and costs $50,000 to implement . 300,000 x 0.10 = $30,000 rebate . Since 50% of $50K = $25,000, only $25,000 will be reimbursed . Total Rebate = $3,000 + $10,000 + $25,000 = $38,000 total APS Rebate Program
Targets non-residential commercial and industrial businesses, and institutions (small and large) . Large Customer > 100kW during month - $500,000/yr . Small Customer < 100kW during month - $150,000/yr . Studies – 50% cost of study up to $10,000/study . Retro-Commissioning – 75% $20,000/study . Pump Tester Program – Managed by Lincus $350-$450 per pump or blower APS Rebate Program
Flat $0.09/kWh saved up to 75% of customer cost available annually for incentives (+ $55/HP for VFD) Example: . ECM saves 300,000 kWh/yr . Costs $50,000 to implement . 300,000 x 0.09 = $27,000 rebate . Since 75% of $50K = $37,500, full $27,000 will be reimbursed . If implementation cost was $30K, rebate would only be $22,500 (30,000 x .75) Energy Billing and Demand Management Demand Management Demand Management Energy Efficiency Use Control demand to less energy for a given process reduce energy cost Energy Efficiency
Demand Resource Management Recovery
Resource Recovery Recover waste energy to offset purchased energy 27 Utility Billing
• Fixed Charges • Independent of demand or usage. • Facility charges.
• Demand Charge (kW) • Typically 15-30 minute peak power demand during a billing period.
• Energy Usage Charge (kWh) • Energy consumed during the billing period. Demand charges are based on peak metered demand Demand ratchets and minimum billing demand
Peak Demand Demand (KW)
90% Annual Demand Ratchet Example “Time of Use” Billing
• Energy & Demand costs change with the time of day. • On peak periods can change seasonally • Very Common
“When” energy is used and “how much” energy is used determines the overall cost. Real-Time Energy Rates
Hourly LMP Data Example
• Cost of energy varies hourly with 0.45
the real time energy market. 0.40
• Real time cost of energy often 0.35
exceeds retail cost during peak 0.30
periods. 0.25
• Benefit from market volatility $/KWH 0.20 through demand response 0.15
programs and real time pricing 0.10 billing rates 0.05
0.00 0 50 100 150 200 250 300 350 Demand Profile Will Impact Energy Costs Utility Billing Rate Determines Energy Management Strategy
10 9 Fixed Charges 8 7 6 Demand Charges 5 4 3 2 Energy Charges
Average Electric Utility Cost ₵/KWH UtilityCost Electric Average 1 0 Plant A Plant B (AZ) Energy efficiency benefit example: LED Lighting
• LED outdoor lighting reduces plant’s outdoor lighting demand by 50kW • Annual Energy Savings - 175,000 kWh per year.
35 Energy efficiency benefit example: LED Lighting
So…..
175,000KWH X 8.5₵/KWH = ~$15,000/yr. of savings right?
Maybe not!......
36 Energy efficiency benefit example: APS LGS Rate - $17/kW any time, $0.041/KWH any time • LED light demand offset - $10,400/yr, • LED light energy usage offset - $7,100/year LED Lighting Evaluation – Water Treatment Plant
1400 1200
) 1000 800 600
Demand (KW 400 200 50kW Peak Demand 0 Reduction 0:00 2:00 4:00 6:00 8:00 0:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 Time Plant Demand Profile 37 Energy efficiency benefit example: APS LGS Rate - $17/kW any time, $0.041/KWH any time • LED light demand offset - 0 • LED light energy usage offset - $7,100/year
LED Lighting Evaluation – Wastewater Treatment Plant
1200
1000 ) 800
600 Peak Demand 400
Demand (KW (No Demand Reduction) 200
0 0:00 2:00 4:00 6:00 8:00 0:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 Time Plant Demand Profile 38 Key Point.
“When” energy is used and “how much” energy is used determines the overall cost.
39 Common Demand Management Strategies
• Manage plant operations to reduce demand during on- peak hours • Defer non-critical operations to off-peak hours • Interlock intermittent loads • Utilize on-site power generation capacity to manage plant demand • Electric utility load response programs
40 Demand Management Case Study – HRRSA (VA)
• Electric Utility Rate • Demand charges - $17.33/KW (any 15 min period) • Energy Charges $0.041/KWH
• Opportunity – Stop non-critical mixing loads during each 20 min filter backwash cycle. • Filter backwash loads (~100hp) • Digester mixing loads (~85hp).
• Annual benefit - ~$10,000/year (@ 80% load factor) in demand savings Case Study – Reduced demand charges through filter backwash timing
Filter Backwashing causing high demand charges
On-Peak Off-Peak $15/KW $1/KW 5.7₵/KWH 3.4₵/KWH
Daily Demands, June 2011
The Cause: Automatic Deep-bed The Response: Move timing to filter backwash process during on- lower demand periods. Potential peak periods - ~150kW to save ~$1500 per month Case Study – Managing demand during on-peak periods
700 Stop Electric Blowers and Start Engine Blowers On-Peak Off-Peak $15/KW $1/KW 600 5.7₵/KWH 3.4₵/KWH
500
400 Average On-Peak Demand – 437kW
300 Demand (KW) 200 Optimum On-Peak Demand – 265kW
Problem: Stopping electric blowers 10 minutes after 100 On-Peak period began. ~$20,000/Year in excess demand charges 0 0:30 1:30 2:30 3:30 4:30 5:30 6:30 7:30 8:30 9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30 17:30 18:30 19:30 20:30 21:30 22:30 23:30 Average Weekday ( kW ) Water Modeling is an Effective Energy Management Tool
Use Less Energy
+ = Energy Cost Energy Management Recovery
Hydraulic Modeling Energy Management Energy Savings
System Modeling can be a very effective tool to identify energy optimization opportunities Hyattown Pump Station – Existing Operations
Hyattown Pump Station Power Demand Profile • Maintain Tank Level 800 100 • On-Peak pumping 700 90 operations resulting in 80 600 elevated energy costs 70 Off Peak On Peak 500 Demand $1.16/KW Demand $15.72/KW 60 Energy $0.035/KWH Energy $0.061/KWH Energy Usage- 400 50 1472MWH/YR Power (kW)Power 300 40 Tank Level (%) Tank Peak Demand 30 200 232KW 20 Yearly Utility Cost 100 10 $68,487 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24
Existing Power Demand Level Existing Hyattown Pump Station – Demand Management and Piping Modifications Hyattown Pump Station Power Demand Profile 800 100 • Piping Modifications to reduce pumping head 700 90 80 600 70 Energy Usage- 500 Off Peak On Peak Demand $1.16/KW Demand $15.72/KW 60 1400MWH/YR Energy $0.035/KWH Energy $0.061/KWH 400 50 Peak Demand
Power (kW)Power 40
300 (%) Level Tank 75KW* 30 200 Yearly Utility Cost 20 100 $40,424 10 0 0 0 2 4 6 8 10 12 14 16 18 20 22 24
Existing Power Demand Optimized Time of Day DM Optimized DM and Piping Mods Level Existing Level DM Level DM and Piping Mods Hyattown Pump Station Operations Optimization
Hyattown Annual Energy Costs Summary • ~$15,000/year of energy $80,000 cost savings at Zero $70,000 Capital Cost $60,000 $50,000 • Minimum billing demand $40,000 limited additional $30,000 demand reduction from $20,000 piping modifications. $10,000 $0 Base Demand Demand Management Management & Piping Modifications On-Site Generators are Valuable Resources
• Capacity Credit Programs • Demand Response Programs • Real-time Energy Markets • Green Energy Markets We Are Outgrowing Our Grid! Utility Distribution Systems
Electric Utility
Utility Grid End User
Electric Utility Customers
Capacity to generate and transmit “peak” power Capacity Credit Programs
• Federal Energy Regulatory Commission Firm Capacity Required (FERC) requires utilities to have firm Customer generation capacity. Owned Capacity • Some utilities will pay customers to use customer owned generators to meet firm capacity (“spinning reserves”). Utility Generation • Customer generators used to meet firm Capacity capacity requirements.
• Generators not used for finical purposes. Capacity Generation Power • Low hours of operation Capacity Credit Case Study Jefferson County Department of Environmental Services (AL)
Village Creek WWTP
• JCDES Village Creek WWTP has 8 – 3.2MW natural gas fueled emergency power generators (25.6MW total) • Used for emergency power only Capacity Credit Case Study Jefferson County Department of Environmental Services (AL)
Alabama Power Rate SG • $2.40/KW/Month with Max annual run time – 200hrs • Requires compliance with EPA National Emission Standards for Hazardous Pollutants (NESHAP) • Typical Run Time – 20 Hrs/Yr • ~$400,000/Yr Demand Response Programs (Economic)
Wholesale Energy Pricing • Customer agrees to reduce load when whole $80 sale market significantly $70 $60 Customer to reduce power exceeds retail energy costs demand during this period $50 • Utility shares savings with $40 customer $30 $20 Average Retail - $10/MWH $10 $0 Energy Management Opportunities Energy Management Opportunities
1. Pumping – Everyone’s got ‘em! 2. Wastewater Treatment 3. Resource Recovery Things to Consider
More Customer stringent satisfaction regulations
Escalating energy costs Facility / equipment renewal
Funding pressures Pumping Considerations
• Design and application • Benefits from Wire to Water (W-2-W) Testing • Proper applications of variable speed systems Equipment Related EEPO - Pumping Improving efficiency of SC pump @ 82% utilization New VFD SC Pump – BEP=4.1 MGD @ 65 psi – Wire to water eff: 75% – Power = 144 HP Old CS SC Pump – BEP=2.6 MGD @ 102 psi – OP PT=4.1 MGD @ 65 psi – Wire to water eff: 50% – Power = 216 HP Saves 385,002 kWh/yr and 72 HP = $34,779/year + $53,145 in potential rebate 385,002 kWh/yr =
Installing 0.22 41,279 440 acres of solar PV gal of gas 100-W light 800,804 lbs. CO2 at $1.05M capital bulbs / year / year removed removed
9.64 MG of cooling water
60 Proper Design & Operation - Pumps
61 Proper Design & Operation - Pumps
62 62 Proper Design & Operation - Pumps
330 gpm410 ft HP 48 1.HP %100 .08.0396094.0944
300 gpm370 ft HP 46 1.HP 75% .0396071 .093921.0
260 gpm330 ft 100% = 60 Hz HP 46 0.HP 50% .0396062 .091835.0 75% = 45 Hz
50% = 30 Hz
63 Proper Design & Operation - Pumps
• Verify NPSHa > NPSHr to prevent cavitation
bar static vapor hHHHNPSHaL
Elevation Barometric Pressure Temperature Vapor Pressure o (ft) (ft) ( F) (ft) 0 33.9 32 0.2 1000 32.7 40 0.28 2000 31.6 50 0.41 3000 30.5 60 0.59 4000 29.3 70 0.84 5000 28.2 80 1.17 6000 27.1 90 1.61 7000 26.1 100 2.19 8000 25.1
* Source - "Advanced Water Distribution Modeling and Management" Proper Design & Operation - Pumps
• Prevent vortexing potential Case Study – Gilbert Site 7 W-2-W Tests
Improvements: Identified “air locked” booster pumps + throttled valves + “potentially” plugged well casing .W-2-W efficiencies ranged from 33% to 62% .New, more efficient pumps, air valves and well pump casing maintenance Results: .Saved 231,300 kWh/yr total OR $23,933/yr .SRP Rebate (to be verified) of $34,177 .ROI for each pump ranged between 3.2 – 5.6 yrs Case Study – Douglas, AZ EEPO
WW Improvements: Identified an “air locked” force main on main LS causing w-2-w efficiency of 29% and 35%
Similar to canal crossing
Air-locking / Horsepower Relationship
air bubble at smaller pipe cross high headloss is high fluid highpoint = sectional area = overcome with velocity = high smaller pipe cross higher fluid higher TDH headloss sectional area velocities pumps = more HP
Case Study – Douglas, AZ EEPO
WW Results: CAV’s before and after wash crossing . Increased flows at theoretically less HP Case Study – Douglas, AZ EEPO
ECM Type Well 6/9/11/15 Well 16 Well 17 Mechanical -Reconfigure Above N/A -Well Pump Water Improvements: Ground Piping Modifications Identified “air locked” well -Well Pump -Install CAVs/Air Modifications Release Vacuum pump discharge pipe and -Install CAVs/Air Release Valves Vacuum Valves
throttled valves so well did not Electrical -More SCADA Reporting -Install PQM -Install PQM Capability -Install PLC -Install PLC sand -Install Power Quality Monitor (PQM) . W-2-W efficiencies ranged from -Install Programmable Logic Controller (PLC) 47% to 69% -Install Level Transducer -Install Magnetic . Minimal automation/trending Flowmeter/Totalizer capability
Operational Clean Vent Clean Line Clean Vent Clean Vent Clean Clean Line Line Case Study – Douglas, AZ EEPO
Water Results: CAV’s at int. highpoint + new pumps w/ VFDs + enhanced instrumentation . Op. flexibility at less HP
. Eliminated purge waste
Run-out op pt. at start-up = max power
FLOW
Case Study – Palo Verde WRF, AZ
Improvements – Identified an “air locked” effluent distribution system through hydraulic modeling and field troubleshooting Results . Replaced non-functioning, improperly specified air release valves (ARVs) with new ones rated for effluent . Installed ARVs at canal crossing highpoints where there were none . Improved wire-to-water efficiency 17% . ROI = 11 months Case Study – City of Fort Collins, CO
Flat face tapping boss would be an ideal place for an air release valve. Currently, there is no means of evacuating air that may accumulate at the top of discharge pipe, prior to turning downward, which can considerably increase headloss due to air Per Aurora Pumps Engineering Newsletter locked pipe. below, split case pumps must use a long radius reducing elbow where at least 10 suction pipe diameters of straight pipe cannot be attained. BFV may help straighten flow.
In the open position, the butterfly valve (BFV) has potential of protruding into the cavity of the check valve upstream, which may prevent it from fully opening. The check valve not fully opening will cause unnecessary backpressure on the pump therefore requiring more HP per gpm delivered. 72 Case Study – City of Fort Collins, CO
73 Wire to Water Case Studies
Savings Opportunities Wastewater Treatment Energy Considerations
Paradigm shift: WWTPs have the potential be become net energy producers . Influent wastewater contains more potential energy than the electrical energy consumed by the treatment plant “Water pollution control facility” “Wastewater treatment plant” “Water reclamation plant” “Resource recovery facility” . Nutrients . Metals Strass WWTP, Austria: . “Indirect energy” 100%+ energy self-sufficient Energy Usage in WWTPs
Typically ~30% of cost of plant operation (EPA)
Personnel So… 45% Solids Disposal 10% Managing and optimizing energy has Maintenance high cost savings potential Energy 3% 30% Chemicals 4% Other 8% Typical Energy Use Distribution in WWTPs
Aeration Clarifiers Source - USEPA 60% 3%
Grit Return Sludge Pumping 1% 1% Screens 1% Gravity Thickening 1% Wastewater Pumping 12% Lighting and Anaerobic Digestion Belt Press 3% Chlorination Buildings 11% 1% 6% Energy Savings Potential in WWTPs
• Energy efficiency • Aeration system • Pump system • Control strategies • Motors • Variable frequency drives
• Resource recovery– energy production WWTP Energy Efficiency • Design • Process selection • Equipment Fine bubble diffusers for highest oxygen transfer efficiency • Process control • Operation and Maintenance Treatment process considerations
• Treatment goals and process selection - major impact on energy demand • Reliability: extended aeration, oxidation ditch: + 30% or more • High-quality effluent: membrane bioreactor: +30% or more • Aeration serves mixing as well as O2 transfer requirements • Mixing demand varies between activated sludge processes (CMAS higher) • Denitrification process recoups oxygen from NO3 • Anoxic basins: avoid oxygen poisoning from internal recycle • Primary clarification – can rob carbon needed for denit process • Aerobic digestion: common at mid-sized to smaller plants • +30% energy consumption • Is it necessary? Energy Optimization – Design Considerations
• Process Selection • Denitrification Benefits • Aeration • Diffusers • Blowers • Controls • Mixing • “New normal” Aeration’s Challenges • Aeration costs = 45-75% of power costs SAE Most diffused aeration systems in AZ already using • Aerator Type lbO2/hp-hr fine bubble/pore aeration High Speed 1.5 – 2.2 • Ongoing challenges • Diffuser performance declines over time fouling/scaling Low Speed 2.5 – 3.5 • Difficult to observe fouling/damage - submerged Coarse Bubble 1 - 2.5 • Cleaning means downtime on basin • Matching capacity to demand Fine Bubble 6 – 8 • Diurnal • Underloaded plants Aeration System O&M Challenges
Fouled Cleaned
Courtesy Dr. D. Rosso, UCLA Photo courtesy of SYB Leu
Damaged Diffuser efficiency declines within 6 to 12 Diffuser months if not cleaned Diffuser Cleaning Impacts on Energy Usage
3,500 200
Time to Clean Again 3,000 Aeration Tanks Cleaned
2,500 150 KWH/MG CF/100 GAL CF/100 2,000
1,500 100 J-00 J-01 J-02 J-03 J-04 J-05 J-06 J-07 J-08 J-09 J-10 J-11 J-12 CF/100 GAL KWH/MG Blower technologies impact energy demand
• Positive Displacement • Multistage Centrifugal • Single-Stage Integrally-Geared Centrifugal • High-Speed Direct Drive Centrifugal Positive Displacement Blowers
• Typically rotary lobe type in WW • Long operational history - Many suppliers • Constant air flow - Variable pressure / liquid depth • Sequencing batch reactors • Membrane bioreactors • Least efficient • Slip around lobes • Inlet/discharge silencers • Turndown via VFD
Courtesy of Dresser-Roots Multistage Centrifugal Blowers
• Variable air flow over narrow pressure range • Multiple impellers in series increase air pressure – similar to a pump • Commonly used - Good track record / reliable operation • Efficient at design point • Steep reduction in efficiency away from B.E.P. • Limited turndown • Inlet valve modulates to change air flow • VFDs can be used Single Stage Integrally Geared Centrifugal Blowers
• Single machined impeller • Constant speed motor • Gearing system increases motor speed to impeller • Proven / reliable operation • Inlet guide vanes modulate to vary air flow • Variable diffusers on discharge • Efficient turndown to 50% or less • Vanes and diffusers controlled with mechanical actuator High Speed Direct Drive (“Turbo”) Blowers
• New to municipal market (1st unit - 2004) • Blower and motor directly coupled • Entire unit built by manufacturer (“core”) • Permanent magnet motors used for higher efficiency at higher speeds • Bearings require no lubrication • Air foil - around shaft • Magnetic – magnets position shaft • Motor / blower speed varied with VFD • Efficient turndown • VFD, controls integrated in blower package Blower Technology Comparison
Type History Energy efficiency Turndown Cost
Positive Well-established 45 - 65% 50 Lower displacement Centrifugal Well-established 50 - 70 % 60 Moderate
Single-stage integral New 70 – 80% 50 High geared High-speed direct Emerging 70 – 80% 60 High drive (“turbo”)
• High-speed blowers provide energy savings over PD and multistage blowers • Lower energy and present worth costs • Proper blower selection is site specific Automatic DO and Blower Control
• Improvements in DO monitoring • Match airflow to demand: Basin location and Diurnal • Tapered diffuser design based on process modeling • Provide proper blower turndown BioWin Chart 900
• Design conditions 800 versus 700 600 • Current realities 500 400
Airflow (SCFM) Airflow 300
200
100
0 1/6/2008 1/6/2008 1/7/2008 1/7/2008 1/8/2008 1/8/2008 1/9/2008 1/9/2008 1/10/2008 1/10/2008 1/11/2008 1/11/2008 1/12/2008 1/12/2008 DATE
Zone 3 - Basins 1&2 Energy savings from reducing DO to reasonable levels DO control with on-line monitoring
• Concept – use aerobic zone ammonia concentration to determine DO setpoints • Benefits: Minimize airflow/energy • Lowers DO return to anoxic/anaerobic zones • Use online analyzer to measure ammonia at last aerobic cell • Zone DO control used (4 zones/basin) • Each has DO probe and modulating air valve • Monitor ammonia concentrations on-line and adjust DO accordingly Process Mixing Energy
• Unaerated zone mixing requirements • Typical power input is 0.3 to 0.4 hp/1000 ft3 (“Textbook Numbers”) • High efficiency mixers with optimal zone geometry/configuration can reduce power requirements by 50 – 60% • Mixing issues need to be considered in design of aerated basins as well • “Mixing-limited” conditions can drive air requirement • Aerated EQ, grit basin or AZ basin mixing can impede denit reaction if DO > 0.5 mg/L Mixing Optimization - Tallahassee FL
• 26 mgd enhanced nutrient removal • “Textbook” Design • Total hp = 300 hp • Optimized design • CFD modeling • Better staging, additional mixers • Total hp = 150 hp • 150 hp reduction (same mixed volume) • $60,000/yr Power Cost Savings Reconsider aerobic digestion
• Aerobic digestion can increase energy cost by 30% • Examine the intended disposal point for the biosolids • Landfill – digestion not required • Beneficial use – Class B – problematic • Monitoring / reporting • Limited Markets • Beneficial use – Class A • Unlimited disposal options • Difficult with aerobic digestion • If plant is functioning in “extended aeration” mode, why also digest? Impacts of the “New Normal” in Arizona • Much slower growth rates • Declining per capita water use • Increasing salinity • Result: Flows Strength • Oversized and under loaded plants • Treating a wastewater stream different from original basis of design • Energy impacts: Excessive aeration capacity, Empty treatment trains, Inadequate turndown ability • Possible corrective actions: • Revised process modeling • Plants may be now in “extended aeration” mode • Close off a train, buy lower-capacity equipment? Salinity Case Study – Rayne Water ZLD System
Improvements: Zero Liquid Discharge (ZLD) enhancements to centralized IX resin regen facility (US Pat. No. 20110077144) Results: . Saved 2.6 MG/yr . Prevented 281 tons/yr of salt from entering sewer . Created solid byproduct for reuse market Won AZ Water’s 2011 Water Reuse Project of the Year Developed a Water Softener Impact Costing Tool in 2012 for AZ Legislature TAC 1. Spent resin XFR
7. Regen Resin XFR 2. BW / BW Recovery
6. Final Rinse 3. Brine / Brine Recovery
5. Initial Rinse 4. Solid Waste Generation Equip. Related EEPO - Blowers
Improving efficiency of blower @ 77% utilization
New VFD HST Blower – BEP=1,360 cfm @ 9.9 psig – Wire to air eff: 69% – Power = 69 HP
Old CS MS Centrifugal Blower – BEP=1,020 cfm @ 12 psig rise – OP PT=1,360 cfm @ 10.9 psig – Wire to air eff: 39.6% – Power = 139 HP Saves 353,976 kWh/yr and 69 HP = $24,778/yr + $44,107 in potential rebate 353,976 kWh/yr =
Installing 0.2 37,952 404 acres of solar PV gal of gas 100-W light 736,269 lbs. at $0.97M capital bulbs / year CO2 / year removed removed
8.85 MG of cooling water
101 Water Treatment Energy Considerations
• Typical C/F WTP Energy Breakdown Non-Process Energy (kWh/yr) Chemical / Mixing Energy (kWh/yr) Pumping Energy (kWh/yr)
19%
51% 30% Water Treatment Energy Opportunities
Electro-coagulation
Disc Filters OR Centrifugal Crossflow Filters Trouble Shooting Techniques Barometric Loop
PSV / FCV
ARV? ARV? ARV?
105 Insufficient CaCO3 plugging lay length Swing check protruding into BFV
Cavitation
ARV? No Partial Stream Treatment
106 Resource Recovery
• Nutrients • Biofuels • Hydraulic Energy Recovery • Renewables (Solar) Utility Of The Future
Treat wastewater as a recoverable resource Recoverable Resources
• Biogas Recovery and Utilization • Hydraulic Energy Recovery “Direct” Energy Offset • Heat Recovery • Renewables (Solar, Wind, etc..) • Nutrients • High Value Carbon • Specialty Waters (Reuse) “Indirect” Energy Offset • Metals • Cellulose Phosphorous Recovery
• Typically recovered from side streams Struvite • Nutrient recovery in biosolids = GHG reduction credits.
919,000 kWh Biosolids recovery and 610 tons/year 1.33lbs of electric energy reuse CO2e CO2e per KWH Equivalent
Offset in GHG production Pounds of GHG (CO2e) for associated with N and P each electric utility KWH fertilizer production generated (E-GRID Data) Biogas Energy Recovery
• “Free” fuel source • Digester gas fueled CHP systems have a long history in the wastewater industry • Generate an average of 20% to 40% of the electric energy usage from municipal sludge • Considered renewable energy source. Typical CHP System
THERMAL ENERGY MECHANICAL ENERGY Generator Building Heat Engine Process Heat Blower Pump
BIOGAS FUEL
Anaerobic Sludge Digesters Engine Alternatives Simplified CHP System Heat Recovery Scheme
Heat Recovery ~40% Efficiency Heat Recovery Glycol Loop Silencer Heat Recovery Water Loop
Engine/Generator ~35% Efficiency Heat Gas Engine Dump Generator
114 Gas Conditioning
• Water, hydrogen sulfide (H2S) and compounds of silicon (siloxane) are the primary contaminants of concern.
• H2S and water combine to form sulfuric acid (H2SO4). Causes corrosion to the internal engine components. • Siloxane causes abrasive compounds similar to glass to build up on internal engine components (pistons, valves, turbos)
Images provided courtesy GE Jenbacher Co-Digestion
• Digestion of high strength organic wastes with wastewater solids • 50 -100% Increase in gas production • Possible revenue from tipping fees • 5₵-15₵ per gallon • Impacts to dewatering and hauling costs • Growing in popularity
116 Co-Digestion Sources
• FOG, dairy waste, brewery waste are desirable high strength waste sources • Nutrients contained in the waste streams are released
117 Bio-Fuels
• Production of renewable vehicle fuels • Pipeline Injection (RNG) • CNG/LNG • Biodiesel / Bioethanol • Offset expensive liquid fuels • Additional benefit from transportation fuel markets (RIN Markets)
118 Hydraulic Energy Recovery Opportunities
Types of turbines Reaction Impulse - pressurized up & down - pressurized up & atmospheric down
PAT-cost effective alternative 119 Hydraulic Energy Recovery Opportunities
CLASSIFICATION OF HYDRO POWER GENERATION CLASSES
>10 MW LARGE
<10 MW SMALL
<1 MW MINI
<100 kW MICRO
<5 kW PICO
120 Equip. Related EEPO – Micro-turbines
Replacing a PRV w/ PAT @ 49% utilization
Pump-as-Turbine (PAT) – Power: 12 HP generated – Water to wire eff: 58%
PRV Station – 1 MGD @ 50 psi drop – Power generated: NONE Generates 38,425 kWh/yr and 12 HP = $3,843/yr + $0 in utility rebate Proper Design & Operation - Micro-turbines
305 gpm ft.055073 350 gpm ft.053079 400 gpm ft.050572 HP 31 HP HP 37 HP HP 36 7.HP %100 3960 75% 3960 50% 3960
100% = 1800 rpm
75% = 1350 rpm
50% = 900 rpm
122 Identifying Energy Recovery Opportunities
Examples of wasted hydraulic head in water/wastewater systems . Pressure Reducing Valves (PRV’s)
Equipment Zone splits protection
123 Identifying Energy Recovery Opportunities
Examples of wasted hydraulic head in water/wastewater systems . Pressure Sustaining Valves (PSV’s) . Pressure Reducing Valves (PRVs)
Distribution system inter-connects Distribution system reservoir fill
RO concentrate Low pressure backpressure effluent delivery124 BP Identifying Energy Recovery Opportunities
Examples of wasted hydraulic head in water/wastewater systems . WRF Outfalls Effluent weirs / outfalls
125 Energy Recovery Devices - PATs
Montrose County, CO Water Authority Head: 117 feet / 50.6 psi Flow: 12.45 cfs / 5,586 gpm Output: 91 kW / 122 HP W-2-W Eff: 73.9% Runtime: 8760 hr/yr Electrical Savings: 797,160 kW-hr/yr
126 Energy Recovery Devices – Reaction Turbine
Swalley Irrigation District, Bend, OR Francis Turbine Head: 160 feet / 69.2 psi Flow: 65 cfs / 29,172 gpm Output: 728 kW / 976 HP W-2-W Eff: 82.8% Runtime: 8760 hr/yr Electrical Savings: 6,377,280 kW-hr/yr
127 Energy Recovery Devices – Impulse Turbine
City of Cortez, CO Water Treatment Plant Pelton Turbine Head: 355 feet / 154 psi Flow: 10 cfs / 4,488 gpm Output: 246 kW / 330 HP W-2-W Eff: 82% Runtime: 8760 hr/yr Electrical Savings: 2,154,960 kW-hr/yr
128 Energy Recovery Devices – Impulse Turbine
Lake Country, BC Water Treatment Plant Pelton Turbine Head: 610 feet / 264 psi Flow: 25 cfs / 11,220 gpm Output: 1,143 kW / 1,533 HP W-2-W Eff: 88.7% Runtime: 8760 hr/yr Electrical Savings: 10,012,680 kW-hr/yr129 Energy Recovery Devices – Turbine as Pump
Replacing a PRV w/ TAP @ 49% utilization
Turbine-as-Pump (TAP) – Power: 16 HP generated – Water to wire eff: 80%
PRV Station – 1 MGD @ 50 psi drop – Power generated: NONE Takes adjacent 0.49 MGD @ 65 psi distribution pump OFFLINE saving 51,230 kWh/yr = $5,123/yr + $5,635 in rebate 130 Energy Recovery Device - Turbine as Pump
The Goodyear AZ TAP Example
Fill Manifold Canyon Trails Reservoir / BPS / Treatment Site
PSV
131 Energy Recovery Device - Turbine as Pump
Goodyear Water Dist. Sys. @ 55- 65 psi
2 MGD VFD 2 MGD VFD
Pump: 1.4 MGD @ 65 psi 2 MG Ground Turbine: 2 MGD Reservoir 2 MGD @ 80 psi @ 75 psi from Liberty Water Dist. Sys.
132 Case Study – Gilbert San Tan Vista WTP MT
Identify “Wasted Head” Quantify the Flow & Head $ Opportunities $ $ $ $ Generate How Often GREEN Does it Power! Operate? Case Study – Gilbert San Tan Vista WTP MT
How much power can it generate/offset? . @ 20-MGD approximately 366-kW & 3,206,160 kWh/yr generated
CAP Inlet HGL: 1,552.00 ft
Color Coding Legend Link: Calculated Friction Headloss (ft) -$256,500/yr -1.7 M lbCO2/yr <= 1.00 -87,451 gal gas <= 15.00 <= 30.00 L: 73,920.00 ft -22.4 M gal/yr D: 48.0 in Vel: 2.46 ft/s <= 60.00 P-1
WTP RW Mix Basin HGL: 1,348.00 ft
Reaction Turbine Q: 13,888.00 gpm J-1 HL: 175.08 ft J-2 P-4 D: 48.0 in P-2 P-3 L: 800.00 ft D: 48.0 in D: 48.0 in Vel: 2.46 ft/s L: 60.00 ft L: 40.00 ft Vel: 2.46 ft/s Vel: 2.46 ft/s Renewables
• Solar • Wind • Micro-hydro • Geothermal HVAC Types of Solar Systems
• Photovoltaic Systems – Converts sun light energy into electric energy • DC power
• Thermal Systems – Recovers thermal energy from sun light • Concentrated solar • Parobolic troughs Photovoltaic Systems
• Crystalline Silicon type most popular • 10 watts/square foot (Rating). • DC power output - inverter is required for AC output (10% efficiency loss). • Fixed system • 1 and 2 axis sun tracking systems • $2.50/sqft • 15-20 year payback w/o credits ~30,000KWH/yr for every Solar Power Generation 1000sqft. (Source NREL PVWatts Tool)
• Charlotte NC PV Generation Potential • Fixed Systems – 12-13 kWh/sq-ft/year • 1 Axis Tracking – 15-16 kWh/sq-ft/year • 2 Axis Tracking – 16-17 kWh/sq-ft/year
• Tuscon AZ PV Generation Potential • Fixed Systems – 16-17 kWh/sq-ft/year • 1 Axis Tracking – 21-22 kWh/sq-ft/year • 2 Axis Tracking – 23-24 kWh/sq-ft/year
PVWatts Tool from the National Renewable Energy Laboratory (NERL) Can be used to estimate solar system benefits “When” power is generated has an impact on overall benefit (Solar Example)
Typical Solar Power Generation Profile (100kW System) Example 60000 Typical On-Peak 50000 Billing Periods 40000 30000
Watts (W) Watts 20000 10000 0 0:00 2:00 4:00 6:00 8:00 0:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 Summer Winter Time Renewable energy systems may not always offset demand charges
Billing Period Demand Profile
5000 No demand offset during 4500 peak period 4000 3500 Plant Demand 3000 kW 2500 2000
Demand Demand (kW) Demand 1500 Period of low or no renewable kW W/ energy generation during peak RE Offset 1000 period (rain event, downtime, etc.) 500 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 AZ Renewable Energy Portfolio Standards (REPS)
• Investor Owned Electric Utilities (APS & SRP) – 15% by 2025 • 30% from distributed generation • Renewable energy obligations are met through 2018
WWW.DSIREUSA.ORG Case Study Solar - City of Raleigh EM Johnson Water Treatment Facility
• 204 kW solar PV system • Year Installed – 2009 • Project Delivery – Third Party (Carolina Solar) • Capital Costs – N/A • Benefit to City of Raleigh • Land lease to Carolina Solar = No Risk Income • Option to purchase solar system in 2016 • Positive public perception Energy Management Program Development Energy Management Program
Explore/Converge Energy Opportunities
Design/Construct/ Understand LONG-TERM Commission Energy ENERGY Opportunity Baselines MANAGEMENT Implementation PROGRAM
Monitor and Verification
Confirm Continuous Process Plant Baseline Development
• All facilities are unique • National baseline data sources for WTP/WWTPs • EPA • WEF-Manual of Practice No.32 • Internal baseline comparison • kWh/MG pumped among all of owners wells…easy to do Energy Modeling
1,600,000
1,400,000 • Energy Modeling = Whole Plant Optimization Optimization 1,200,000 Opportunities 1,000,000 • “Plant specific” energy model 800,000 Current • Energy consumption for each 600,000
process 400,000 Ideal
• Rapid analysis of process Energy Consumption (kWh/year) 200,000
energy scenarios 0 Future Energy Outlooks
Projected Industrial Energy Prices: Electric, Liquid Fuel, and Natural Gas 30 (Source: EIA Annual Energy Outlook 2011)
25
20
15 ~2% 20% - 30%
2009$/MMBTU Difference Difference 10
5
0 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 Elec Reference Elec High growth Elec Low growth NG Reference NG High growth NG Low growth Liquid Fuel Reference Liquid Fuel High growth Liquid Fuel Low growth Power monitoring is key to energy management and optimization
• Real time analysis of energy performance • Monitor key performance indicators (KPIs) • “Reactive to Proactive” • Can be used as trouble shooting tool • Helps dial in on individual plant load center performance…see next slide “High Performance” Power Monitoring
“Bridge the gap between energy usage and process operations” “Levels” of Power Monitoring
149 EM Program Development Summary
• Start with EM program development Projects Implementation • Find low cost/low risk EM Program opportunities Alternative Energy Process Upgrades • Develop implementation Energy Efficient Equipment plan after EM opportunities Demand Management are identified and Process Optimization Optimize Existing Infrastructure understood Energy Modeling and Benchmarking (HEET) Energy Management Power Monitoring & Process Control Program Foundation Utility Billing Rates and Configuration Current and Future Energy Costs EEPO Questions?
Eric Dole Curt Courter [email protected] [email protected] 602-881-0186 480-404-5009
Bryan Lisk Doug Kobrick [email protected] [email protected] 919-349-6529 602-826-2454