evaluating green energy options at water and … · options at water and wastewater treatment...

Evaluating Green Energy Options At Water And Wastewater Treatment

FacilitiesFrederick Bloetscher, Ph.D., P.E.

Florida Atlantic University

• 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

Energy Costs for Water and Wastewater Treatment Plants

are Significant

3

Treatment ProcessPower (MW)/MGD

Aeration/HSP/wells 1.4Lime Softening 2.3Nanofiltration 125 psi 2.7LPRO >200psi FL RWS 3.3Secondary WWTP Air 1.6Secondary WWTP Pure OX 3.4Reuse 3Seawater desalination 13

Examples

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

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

Fine Bubble Diffusers

Turbo-Blowers

DO Control

2.3 Literature Review – ECIs – DO Control (2.0 mg/L)

Auto DO Control

DO Control

DO SetpointControl

Auto DO Control

DO Control

0

10000

20000

30000

40000

50000

60000

70000

City of Boca Raton WWTP

South Central Regional WWTP

Seacoast Utilities PGAWWTP

East Central Regional WWTP

Palm Bch Co Southern Regional

WWTP

kwh

per y

ear p

er M

GD

sav

ed

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

Projected Savings ECIs @ 5 WWTPs)

Power Use

Digester

Capital Saving

Regional Solution

Reduced Grid Power

Demand

Energy Capture

Ag solution

Customer KWhr Power

Savings

Increased Yield

New Jobs Energy Subsidies

Sludge New Jobs

New Jobs

In Addition to ECIs, WWTPs..

Clarifier Sludge

Return to Aeration Basin

Gravity Thickener

Digester

Methanescrubber

Belt Press

Ag Use Treatment

For a 100 MGD plant, incoming solidsAre equal to 80 tons/dSludge from Clarifier is 1% solidsGravity Thickener sludge is 2-4% solidsDigester convert half solids to methaneand rest is 4% solidsBelt press converts to 20-24% solidsBelt press will be 45 tons/d solids

Mini-turbines

17

North District Wastewater Treatment Facility

2401 N. Powerline Road, Pompano Beach, FL 33069

•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

Example

18Image Courtesy of Broward County Property Appraiser website

Modules A-E

AnaerobicDigesters

ElectricalBuilding

Dewatering/Reclaim

Administration

Laboratories/AdministrationInjection Wells

Reuse Storage

Chlorine Facilities

Example

19Data supplied by Hazen and Sawyer

Power Use – Note large amount for Aeration

Easy Stuff

• Aeration Modules (10-25%)– ECIs – 20-50%– VFDs

• Deep Well Injection (<2%)– Slip Recovery

• Admin Facilities (<5%)– CFC Bulbs, White roofs, 18-21 SEER HVAC,

Insulation

Green Power Options

• Digester Gas– Microtubines– Electric Generators– Fuel Cells

• Wind Turbines• PV cells

22

Methane GeneratorsEngine overhaul in 10 years

Minimal maintenanceEach 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

Example

23

MicroturbinesNo major repairs

Minimal maintenance$2000 routine maintenanceEach shift checks equip. – about $20k/yr labor


PW - $2.32 million

Energy Generated (20 years) – 350 million kWhror 48,000kWhr/d (36%)


Example

24

Fuel CellsNo major repairs

Maintenance contracted out$700,000 per year


PW - $23.5 million

Energy Generated (20 years) – >360 million kWh or 50,000 kWh/d or 37%


Example

25

Photovoltaic Cells2 major repairs – hurricane damage

Full-time employee for maintenanceSpecialty Labor - $50,000 salary3% annual raise


PW - $5.3 million

Energy Generated (25 years) – >27 million kWh or 3000 kWh/d or 2%


Example

26

Wind Turbines1 major repair – hurricane damage

Full-time employee for maintenanceMaintenance Technician – $40,000 salary3% annual raise

$180,000 – capital investment

PW - $990,000

Energy Generated (20 years) – 480,000 kWh

$2.06 per kilowatt-hour

Example

MethaneFuel Cell Generator Microturbine

power generated (mil kWh) (20yr) 360 250 350present worth value ($mil) (20yr) 23.5 1.5 2.32$/kWh $0.07 $0.01 $0.01 % of electric consumption 37% 26% 36%

Evaluation (wind and PV panels are <2%)

Example Onsite Generated

Power Source PecentMisc Upgrades 5ECI 20

Methane Turbines 36Wind 0PV panels 2

63

WTP

2 MGD NF Water Plant

• Floridan• Ocean

concentrate

permeate

Rawwater

2 MGD NF Water Plant

Load Number Current(kW)

Future(kW)

Difference(kW)

High Service Pumps 4 134.1 134.1 0.0Backwash Pump 1 55.9 55.9 0.0Lime Slurry Pumps 2 7.5 7.5 0.0Sludge Pumps 2 4.5 4.5 0.0Accellator Drives 3 22.4 22.4 0.0Nanofiltration MembraneFeed Pumps 3 0.0 223.5 223.5

Degasifier Blower 1 - 7.5 7.5Chemical Dosing Pumps 10 3.7 1.9 -1.9Membrane CleaningPumps 1 - 18.6 18.6

Lights, A/C, and Controls lot 7.5 18.6 11.2Sum 235.6 494.5 258.9

Existing vs Future Power

• Conservation• Fuel cells• Solar cells• Wind turbines• Pressure recovery• Compressed landfill methane

Options Considered

• Existing System– Building and Facility 510

kW

• Improved System– Building (-) 1.85 KW– Treatment 325 kW– Site (-) 0.75 kW

• Net Increase 322.4 kW33

http://www.germes-online.com/

Conservation

• High pressure energy recovery system

• Interstage turbine for power production

• Energy recovery to optimize plant needs

www.pumpengineering.com

34

Energy Recovery Systems

• Standard Panels – 3’ X 5’ (12 s.f.)• Access Spacing around perimeter

– 2’ additional length, average • 21 s.f. per panel required

35

Storage Capacity needed –FPL Commercial Buyback Arrangement

Solar Power

C.W. and West

East Area

Mon Well Area

Main Building and West Canopy

Tank Top Area

Parking Canopy

N

36

Solar Options

10,000 SF Available

1 Solar Panel per 20 s.f Area

Wind Turbines combined over

panels – 1 per 50 s.f. Area

37

N

Offsite Wind + Solar

Location # Panels Power (kW)

Building 198 59.4East 352 105.6Tank 262 78.6Pond / West 693 248.7Parking 162 48.6Wells 270 81.0Offsite + Wind 667 185.6SUBTOTAL 2,740 806.9

38

On-site Solar - $3.5 M

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

Questions?

Threatened RM greenback cutthroat trout

evaluating green energy options at water and … · options at water and wastewater treatment...

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