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Silvester Park
5 years ago
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3 WHY IS ENERGY EFFICIENCY IMPORTANT? Energy costs will rise faster than inflation Budget trends continue tightening Highest priorities are elsewhere Resources are already stretched Improving Energy Efficiency is the right thing to do

4 ENERGY EFFICIENCY MAY BE THE BRIDGE ENERGY EFFICIENCY

5 SO WHERE DO WE BEGIN... THE TOP 10 LIST OF ACTION ITEMS With the end in mind!

expectations $35 $30 $25 Share Energy Consumption with Staff $20

6 10. DEVELOP AN ENERGY TEAM Identify an Efficiency Team Leader Tap Expertise that is already on staff Establish, but manage expectations $35 $30 $25 Share Energy Consumption with Staff $20 $15 $10 $5 $0 Incentivize Energy Efficiency Dec 2013 Dec 2014 Dec 2015 Dec 2016

7 9. BENCHMARKING 3,500 WWTP Unit Energy Consumption kwh/mg 3,000 2,500 2,000 1,500 1, Lagoons Trickling Filter Activated Sludge Extended Air Plant

4,500 Existing Specific Energy Consumption 4,000 3,500 3,000 kwh/mgal 2,500 2,000 1,500 1,000

8 4,500 Existing Specific Energy Consumption 4,000 3,500 3,000 kwh/mgal 2,500 2,000 1,500 1, Oso Greenwood Allison Laguana Madre Whitecap One Utilities Unit Energy 5 WWTPs

9 TYPICAL WWTP POWER DISTRIBUTION Raw Water P.S. Headworks Primary P.S., Clarifier Process Activated Sludge Sec. Clarifiers RAS Thickener, P.S. Effluent Filters Utility Water Solids Dewatering Heating Lighting Post Aeration/Cl 2 Mixer Percent of Total Plant Energy

10 Half of plant energy is in the aeration system or MORE

11 8. IDENTIFY AREAS FOR ENERGY IMPROVEMENTS Look For the Low Hanging Fruit Control Setpoints Throttling Valves Undersized & Old Valves and Piping Worn / Vibrating equipment

12 LOOK AT THE ENERGY HOGS ENERGY AREA Aerator Type Blower Type Controls Philosophy Correct Overdesign POTENTIAL SAVINGS ~30% Coarse or Mechanical to Fine Bubble ~10% High efficiency blowers ~30% DO controls ~10% to 25% proper sizing Up to 60% Aeration System Energy Savings Potential

13 7. DEVELOP ENERGY OPTIMIZATION PROCESS Obtain System Knowledge Conduct Inventory, Determine Distribution of Power Benchmark to Similar Facilities Determine Efficiencies Detailed Analysis Create ECMs Quantify Promising ECMs Develop Implementation Program Implement

14 6. ASK WHAT IF... We changed/modified a process Look at every process We Turned it down/off for a while Look at All Equipment Peak consumption is reduced Moved to off-peak hours Life Cycle Perspectives Used Lower total costs Start Low Hanging Fruit move to the Biggies Stay with Best Practices and Proven Technologies

15 5. IDENTIFY (& ADDRESS) IMPEDIMENTS TO ENERGY IMPROVEMENTS Buy-in from the big bosses (Mayor, Council, Board, etc.) If it ain t broke... But maybe it can work better faster, cheaper We re doing the best we can with what we have We ve always done it this way If I save money, it ll just go to build a.... I don t have anything against new technology, there just won t be any at my plant.

16 4. OVERDESIGN CAN STEAL ENERGY TYPICAL PEAKING FACTORS PEAKING FACTOR PARAMETERS Average Condition Worst Case Peaking Factor Peak Day vs. Average Day CBOD Diffuser Alpha Peak Day vs. Average Day Ammonia Diurnal: Maximum Hour vs. Average CBOD Design Year vs. Startup Loads Regulator Standards vs. Actual

17 WHAT S THE BOTTOM LINE? A total safety (or peaking) factor of 5.5 to 6.0!

18 EXAMPLE: TYPICAL BLOWER DESIGN Average Current Air Demand 5,000 CFM Worst Design Horizon 28,500 CFM Blower # 1 14,250 CFM Blower # 2 14,250 CFM Blower # 3 14,250 CFM

19 TYPICAL BLOWER DESIGN Discharge Pressure (psi) Avg: 5,000 CFM Surge: 7,100 cfm 5,000 10,000 Flow (cfm) Blower Design: 14,250 cfm 15,000

20 SOLUTIONS Size Blowers to accommodate average conditions efficiently Use multiple blowers to achieve Maximum Requirements kw-hrs

21 3. EVALUATE ENERGY SOURCES Current Supplier Rate Structure o Demand Charges, o Time of Day Rates, o Fixed Charges, o Graduated Rates Solar / Photovoltaic Digester Gas Recovery

22 2. FULLY ENGAGE STAFF Training Incentive Programs Access to Energy Consumption and Billing Data Listen to Staff s suggestions

23 1. JUST DO IT Start Low Hanging Fruit Bring in outside resources if needed Develop CIP Projects Procurement / Funding Strategies Reap Rewards

24 CASE STUDY #1 {HARRIS COUNTY} Start Condition Originally Design as an HPO system in late 1980 s Converted to Mechanical Aeration in 1992 Conversion reduced functional capacity threefold Study Focus Convert to Fine Bubble Diffusers Single Stage Blowers w/ variable capacity controls Enhance Functional Capacity

25 Aeration Basin Section (5 Each) Purge Air Exhaust Aerators Purge Air Supply ~ 6,000 cfm 15% O 2 17% O 2 19% O 2 21% O 2 Effluent 30 RAS Influent

26 STUDY RESULTS Millions $2.5 $2.0 Aerator Conversion Savings $1.96 Construction Cost (est.) $6 million $1.5 $1.0 $0.74 $1.22 Energy Savings 62% $0.5 $0.0 Annual Operating Costs - Current Annual Operating Costs - Proposed Annual Savings Payback Period 5.8 Years

27 CASE STUDY #2 {FORT BEND COUNTY} Start Condition Fine bubble Diffusers Multi-stage C/S Centrifugal Blowers Manual DO Control Set Once/Day Study Conditions Basin DO, Plant Flow, Airflow, Temp, Power, etc. Monitoring Frequency 10 minutes for 3 weeks Calculated Excess Air & Energy Automatic DO 2 mg/l

28 Aeration Efficiency Study Basin Layout

29 Aeration Efficiency Test Data Average Dissolved Oxygen (mg/l) :00 AM 1:00 AM 2:00 AM 3:00 AM 4:00 AM 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM 11:00 PM 12:00 AM Time of Day Actual Dissolved Oxygen Actual Air Flow Air Flow (CFM)

30 Energy 82 Costs 0 (Percent of Total) 100% AERATION BASIN LAYOUT STUDY 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Energy Saving with Aeration Controls 100% = Current Energy Use Test Basin Test Basin Influent End Potential Energy Savings Aeration Volume 33,000 Cu. Ft. 246,900 Gal. (Typ for 5) Average SWD = feet 36% Average Energy Savings Projected Energy Consumption 25 0 (Typ. For 5) Effluent End Time of Day Optimized Energy Cost

31 CASE STUDY #2 - RESULTS Construction Cost $350,000 Annual Savings $ 40,000 Savings in Aeration Energy 36%

32 CASE STUDY #3 {BRAZORIA COUNTY} Base Condition Coarse Bubble Aeration Deep Aeration Basins Draft Tubes Contact Stabilization Process Nitrification Multi-stage Centrifugal Blowers Improvements Converted to Fine Bubble Four Turbo-style blowers for full coverage Installed DO Control Conventional Activated Sludge ESCO Procurement Doubled Effective Capacity

33 Nitrification Zone Sludge Re-Aeration Zone Influent Existing System Flow Configuration

34 Nitrification Zone Activated Sludge Proposed Configuration Fine Bubble Aeration Added to All Basins Influent Add Baffle Wall B B B B New Blowers Add Baffle Wall Re-Route Influent to Outer Aeration Basin

35 300 4 Turbo-Style 75 HP Each Coverage & Power Draw HP Draw ,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 Air Demand (SCFM) 1 Blower 2 Blowers 3 Blowers 4 Blowers Desired Air Flow Range Existing Blowers

36 CASE STUDY #3 - RESULTS Annual Savings $ 140,000 Payback Period 10 years Double effective plant capacity APWA Texas Chapter 2015 Project of the Year