Innovative Tools forEnergy Savings

T. Allbaugh, P.E., S. J. Kang, Ph.D., P.E. , K. Williams, P.E., W. Kramer, P.E., G. Jones, P.E.,

K. P. Olmstead, Ph.D., P.E., L. Thomas, M. Jessee, S. Westover, P.E.

in Municipal WWTPs

Typical Energy Usage in U.S.Wastewater Treatment Plants

• Electricity at Average Plant: – 1500 kWh/Million Gallons (MG) treated for

secondary treatment–Advanced Treatment Plant: 2000 to 3000

kWh/MG

• Other Energy Use– External supply of Carbon; methanol; Micro-C–Natural gas

Reasonable Expectations

Typical Power Use Distribution

Case History: Energy Optimization Study at 46 MGD Tertiary Treatment Plant

• Energy Optimization Team: Operation, safety, maintenance, administration

• Process optimization• Utility bill and energy use analysis• Develop alternatives and assess feasibility • Life-cycle costing• Priority ranking by team votes• Funding decisions

YCUA WWTP

• Recently expanded for 46 MGD average design flow

• Tertiary treatment (biological P removal, filters, UV disinfection)

• Belt presses and fluid bed incinerator

• All flow is pumped to the site

Base Line Energy Costs

• $2.7 M at WWTP/year• $0.4 M at pump stations/year• Average 9 cents/KWH

• Team Goal : Save 5% or more

Power Consumption in KW Before

1538

798

750

189180107 146 boiler

aeration

solids

lighting

incineratordrywell vent

Misc.

Average Power Use Before the Project3708 KW

1418701

370

91 015

65 0

KW after

Boiler(7.7%)AerationSolidsLightingIncin RmDrywell VentMisc

Average Power Use After Implementation2655 KW

Aeration Blowers

• A centrifugal blower system supplies air to aeration, filter backwash, and clear well

• At current loadings, the power requirement could be reduced from 1,070 to 940 hp for one blower modification– COST: $76,000– SAVINGS: $68,000 per year

• Payback in 14 months

Demand Anticipation

• Demand Charge = Single highest 30-minute integrated reading of the demand meter during on-peak hours

• In place for 12 months• $13.75 per kilowatt • Target decrease 300KW ($49,500/year)• Defined protocol for operator response

Demand HistoryYCUA WWTP - Maximum Electrical Demands

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

Mar-08

Apr-08

May-08

Jun-08Jul-0

8

Aug-08

Sep-08

Oct-08

Nov-08

Dec-08

Jan-09

Feb-09

Months

Max

imum

Dem

and

(kW

)

HV Controls in Solids and PSST Building

• Original HV equipment controls have been disconnected; system is presently being run manually

• Upgrade controls to Direct Digital Controls (DDC) with METASIS system– COST: $240,000– SAVINGS: $140,000 per year

• Payback in < two years

Intermittent Ventilation for Process Areas

• Dewatering area, cake trucking area, and blower building not always occupied; continuous ventilation unnecessary

• Install local controls, METASYS programming, and H2S/O2 alarm systems to only turn on HVAC when areas are occupied– COST: $40,000– SAVINGS: $43,000 per year

• Payback < one year

Incinerator Room Heat Recovery

• Space above fluid bed always HOT• Boiler combustion air un-tempered in winter• Adjacent dewatering area requires 12 air

changes per hour• Project provides additional heated ventilation

to dewatering, and pre-heated combustion air for boilers

Building Lighting Philosophy

• Original design incorporated highly efficient lights on 100% of the time in galleries and process areas

• Changes incorporate slightly less efficient lights but provide immediate illumination

Lighting System Retrofit

• Fixtures are original, 1970s T12 fluorescent and metal halide High-Intensity Discharge (HID) lights

• Replace all T12 with T8 lamps– Non-HID fluorescent tubes with electronic ballasts– COST: $265,000– SAVINGS: $110,000 per year

• Payback in < three years

Intermittent Ventilation of Drywells at Four Pump Stations

• Crews enter once per week for two hours• Engineering standards call for:– Six air changes per hour , or– Thirty air changes for ten minutes

• Upgrade controls with SCADA– COST: $40,000– SAVINGS: $21,000 per year

• Payback in two years

Adopted Plan

• Optimization Study Cost: $59,000• SRF Project Plan for $1.0M approved with 40%

forgiveness of the loan principal, July 2009• Design and construction underway, 2010-11• Annual Cost Savings: $450,000, or 11%

savings

Summary of Selected ProjectsDescription Annual

SavingsEst. Capital

CostPayback Current

UsageExpected Usage % Reduction

Aeration Blower

$68,000 $76,000 14 months 800 kW 700 kW 12.1

Demand Anticipation

$50,000 $160,000 3 years, 3 months

N/A N/A N/A

Intermittent Process Area Ventilation

$43,000 $40,000 11 months 47 kW 14 kW 70

HV Control Upgrades

$140,000 240,000 1 year, 9 months

750 kW 370 kW 51

Incinerator Room Heat Recovery

$19,000 $65,000 3.5 years - - 5

Lighting System

$110,000 $265,000 2 years, 6 months

189 kW 91 kW 52

Intermittent Drywell Ventilation

$21,000 $40,000 2 years 107 kW 15 kW 86

TOTAL $451,000 $886,000 --- 1891 kW 1191 kW 37

Questions?