Evaluating Green Energy Options At Water And Wastewater Treatment Facilities. Frederick Bloetscher, Ph.D., P.E. Florida Atlantic University

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1 Evaluating Green Energy Options At Water And Wastewater Treatment Facilities Frederick Bloetscher, Ph.D., P.E. Florida Atlantic University

2 Energy Costs for Water and Wastewater Treatment Plants are Significant Often among the largest user on power grid Must provide service 24/7 Power demands cannot be shifted Back-up usually provided leads to load agreements 2

3 Examples Power Treatment Process (MW)/MGD Aeration/HSP/wells 1.4 Lime Softening 2.3 Nanofiltration 125 psi 2.7 LPRO >200psi FL RWS 3.3 Secondary WWTP Air 1.6 Secondary WWTP Pure OX 3.4 Reuse 3 Seawater desalination 13 3

4 There is a difference Water plants produce few useful residuals except pressure Wastewater plants produce lots of organics that can be useful and there are significant inefficiencies

5 Identification of Energy Conservation Improvements (ECIS- WWTPs) Equipment - Fine Bubble Diffusers Equipment Turbo Blowers Equipment - Automatic DO Control (2 mg/l) Operation Auto. DO Setpoint Control (0.5 mg/l) Operation Most Open Valve Blower Control vs. Pressure Setpoint

6 Fine Bubble Diffusers

7 Turbo-Blowers

8 Turbo-Blowers

9 DO Control

10 DO Control

11 DO Control 2.3 Literature Review ECIs DO Control (2.0 mg/l) Auto DO Control

12 DO Control Auto DO Control DO Setpoint Control

Projected Savings ECIs 70000 @ 5 WWTPs) kwh per year per MGD saved 60000 50000 40000 30000 20000

5 mg/l) Automatic DO Control (2 mg/l) Upgrade to Turbo Blowers Fine Bubble Diffusers 0 City of Boca

14 Projected Savings ECIs 5 WWTPs) kwh per year per MGD saved MOV Control vs. Pressure Setpoint Automatic DO Setpoint Control (0.5 mg/l) Automatic DO Control (2 mg/l) Upgrade to Turbo Blowers Fine Bubble Diffusers 0 City of Boca Raton WWTP South Central Regional WWTP Seacoast Utilities PGAWWTP East Central Regional WWTP Palm Bch Co Southern Regional WWTP

15 Power Use In Addition to ECIs, Sludge New Jobs WWTPs.. Digester Regional Solution Ag solution Increased Yield Energy Capture Reduced Grid Power Demand Capital Saving Customer KWhr Power Savings New Jobs Energy Subsidies New Jobs

16 Return to Aeration Basin Methane scrubber Clarifier Sludge Mini-turbines Digester Gravity Thickener For a 100 MGD plant, incoming solids Are equal to 80 tons/d Sludge from Clarifier is 1% solids Gravity Thickener sludge is 2-4% solids Digester convert half solids to methane and rest is 4% solids Belt press converts to 20-24% solids Belt press will be 45 tons/d solids Belt Press Ag Use Treatment

Example North District Wastewater Treatment Facility 2401 N. Powerline Road, Pompano Beach, FL 33069 Largest power user on the grid >4GWh/mo. (>$300k/mo.

17 Example North District Wastewater Treatment Facility 2401 N. Powerline Road, Pompano Beach, FL Largest power user on the grid >4GWh/mo. (>$300k/mo. Bill) Serves over 1 million people from Tamarac to Palm Beach County line Flow > 84 MGD, Capacity = 100 MGD 66 MGD to ocean outfall that is proposed to be abandoned bb.fau.edu 17

18 Example Reuse Storage Modules A-E Dewatering/ Reclaim Anaerobic Digesters Administration Electrical Building Laboratories/ Chlorine Injection Administration Wells Facilities Image Courtesy of Broward County Property Appraiser website 18

19 Power Use Note large amount for Aeration Data supplied by Hazen and Sawyer 19

20 Easy Stuff Aeration Modules (10-25%) ECIs 20-50% VFDs Deep Well Injection (<2%) Slip Recovery Admin Facilities (<5%) CFC Bulbs, White roofs, SEER HVAC, Insulation

21 Green Power Options Digester Gas Microtubines Electric Generators Fuel Cells Wind Turbines PV cells

22 Example Methane Generators Engine overhaul in 10 years Minimal maintenance Each shift checks equip. about $20k/yr labor $1 million capital investment PW - $1.5 million Energy Generated (20 years) >250 million kwh or 34,000 KWhr/d = 26% 0.7 cents per kilowatt-hour 22

23 Microturbines No major repairs Minimal maintenance $2000 routine maintenance Each shift checks equip. about $20k/yr labor $2 million capital investment PW - $2.32 million Example Energy Generated (20 years) 350 million kwhr or 48,000kWhr/d (36%) 0.6 cents per kilowatt-hour 23

24 Example Fuel Cells No major repairs Maintenance contracted out $700,000 per year $14 million capital investment PW - $23.5 million Energy Generated (20 years) >360 million kwh or 50,000 kwh/d or 37% 4.90 cents per kilowatt-hour 24

25 Photovoltaic Cells 2 major repairs hurricane damage Full-time employee for maintenance Specialty Labor - $50,000 salary 3% annual raise $3 million capital investment PW - $5.3 million Example Energy Generated (25 years) >27 million kwh or 3000 kwh/d or 2% 19.4 cents per kilowatt-hour 25

26 Wind Turbines Example 1 major repair hurricane damage Full-time employee for maintenance Maintenance Technician $40,000 salary 3% annual raise $180,000 capital investment PW - $990,000 Energy Generated (20 years) 480,000 kwh $2.06 per kilowatt-hour 26

360 250 350 present worth value ($mil) (20yr) 23.5 1.5 2.

27 Evaluation (wind and PV panels are <2%) Methane Fuel Cell Generator Microturbine power generated (mil kwh) (20yr) present worth value ($mil) (20yr) $/kwh $0.07 $0.01 $0.01 % of electric consumption 37% 26% 36%

28 Example Onsite Generated Power Source Pecent Misc Upgrades 5 ECI 20 Methane Turbines 36 Wind 0 PV panels 2 63

29 2 MGD NF Water Plant WTP

30 2 MGD NF Water Plant Floridan Ocean concentrate Raw water permeate

31 Existing vs Future Power Load Number Current Future Difference (kw) (kw) (kw) High Service Pumps Backwash Pump Lime Slurry Pumps Sludge Pumps Accellator Drives Nanofiltration Membrane 3 Feed Pumps Degasifier Blower Chemical Dosing Pumps Membrane Cleaning 1 Pumps Lights, A/C, and Controls lot Sum

32 Options Considered Conservation Fuel cells Solar cells Wind turbines Pressure recovery Compressed landfill methane

33 Existing System Conservation Building and Facility 510 kw Improved System Building (-) 1.85 KW Treatment 325 kw Site (-) 0.75 kw Net Increase kw 33

34 Energy Recovery Systems High pressure energy recovery system Interstage turbine for power production Energy recovery to optimize plant needs 34

35 Solar Power Standard Panels 3 X 5 (12 s.f.) Access Spacing around perimeter 2 additional length, average 21 s.f. per panel required Storage Capacity needed FPL Commercial Buyback Arrangement 35

36 Solar Options Main Building and West Canopy C.W. and West N Mon Well Area Parking Canopy East Area Tank Top Area 36

37 Offsite Wind + Solar N 10,000 SF Available 1 Solar Panel per 20 s.f Area Wind Turbines combined over panels 1 per 50 s.f. Area 37

38 On-site Solar - $3.5 M Location # Panels Power (kw) Building East Tank Pond / West Parking Wells Offsite + Wind SUBTOTAL 2,

39 Conclusions WWTPs offer significant opportunities to reduce power off the grid, but the incentives to invest in technology are lacking as is capital Water Plants have much fewer opportunities Site Specific for PV, Wind Incentives needed for green power (wind, PV) federal exist, but not power industry Conservation savings minimal

40 Questions? Threatened RM greenback cutthroat trout

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