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Energy Efficiency for Water and Wastewater Systems

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WelcomeWelcome

Trainer:Jake Salcone

RCAC – Portland, ORRural Development Specialist – Environmental

Event:Washington D.C. RCAP conference

December 2010

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Why Energy Efficiency?

Some 4% of the nation’s electricity use goes towards moving (80%) and treating water/wastewater*

Electricity costs are increasing rapidly; efficiency is cheaper in the long-run

Funding programs have increasing preference for “green” projects

Efficiency can extend life of assets Less energy means lesser demand for power – ALL

power generation has an environmental impact

*Water and Sustainability: U.S. Electricity Consumption for Water Supply & Treatment—TheNext Half Century, EPRI, Palo Alto, CA: 2000. 1006787.

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The Problem:

Water weighs 8.34 lbs/gallon. We use ~60 gallons/day, which means we move 500 lbs of water miles and miles, for every individual, everyday.

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The Problem:

1 MGD plant moves about 4,120 tons of water each day

Plants commonly designed to handle max capacity not operate at lowest cost

Many new technologies in motors, HVAC, and lighting have not been adopted in water and wastewater systems

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Power Costs and Power Prices

Utility power cost includes:Maintenance and operation of power delivery

infrastructure – transmission and distributionCost of powerCapacity for peak demand

Billing rates or tariff structures often aimed at discouraging peak demand

“Small Industrial” customers should evaluate electricity requirements versus billing structure

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Energy Audit

Range from simple walk-through to detailed engineering and return-on-investment analysis

Level of detail depends on goals TAP vs. Utility Representative Steps:

Identify Quantify Verify

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Where is the energy going?

Pumping Aeration

According to the Consortium for Energy Efficiency (CEE), aeration typically accounts for the largest share of energy consumption, 60% at an activated sludge WWTP.

Dewatering U.V. Lighting HVAC Odor Control

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Categorical Efficiencies

Any water conservation measure is an energy conservation measure

I&I reduction is an efficiency measure Basic systems use less energy

Energy Consumption of secondary

treatment

*Energy Audit Manual for Water/Wastewater Facilities; EPRI 1994

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Energy Audit: Data Collection

Plant Flows Electric Bills and Billing Schedule Design Summary Equipment Inventory Pumping records and performance curves Operating times for pumps and other processes Plant management and operations strategies Previous energy audits

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General Guidelines for Finding Efficiency Opportunities

Does the process/equipment need to run at all? Find loads that run continuously or nearly

continuous - Is it possible to run the process/equipment for fewer hours?

Look at your electrical diagram and pick out big motors

Look at equipment more than 10 years old

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Tune-Ups vs. Capital Projects

Is the process efficient at most common load conditions, or does equipment need modified or replaced? e.g. Run more efficient pumps for normal base loads

and use lower-efficiency, larger units for only peak flows

Systems that are run on simple or no control – Can controls be added/improved?

Evaluate tune-up savings vs. new equipment savings

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Example Energy Conservation Measures (ECMs)

Motor/pump output optimization System-wide optimized pumping strategies System-wide pressure management

strategies Metering/Billing/Rate Leak/I&I detection and repair technologies

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Pumping

Pumps should be selected for maximum efficiency at average flow, not maximum capacity. Multiple pumps can meet peak demand Use your most efficient equipment first and most often Swap out old motors rather than rewinding Check that your pump impellers are correct for actual conditions

Compare Variable Frequency Drives to cycling pumps on and off

*High Efficiency motors will eventually become standard, so get your incentives now!

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Pumping Cont.

System Pressure: Upsize sewer force main or water main size. Allow pump station basins to fill higher before

pumping to reduce head Replace lift-station with gravity sewer

*Most process pumps are fairly low head, so 2 or 3 feet of pressure difference can be a good percentage of total head.

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Aeration

Aeration systems are huge consumers – up to 60% of total plant demand!

Switch to fine bubble diffusers – 30% + reduction over coarse air

Install active DO control, or utilize what you already have Upgrade to modern blowers with efficient turn down

capability Use cascaded control strategies Are you nitrifying? Do you need to?

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Fine-Bubble Aeration

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Other Energy Loss

Dewatering Centrifuge uses ~ 6 x more horsepower than belt filter or

screw-press

U.V. Low-pressure, high efficiency lamps more efficient than

medium pressure lamps Match number of lamps to flow

Lighting T5 lamps, motion sensors

HVAC Seal-tight, ventilate right Use waste-heat from motors, generators, etc. Heat pumps

on effluent

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Energy Efficiency Incentive Programs

Why do electric utilities want you to SAVE energy?

Transmission constraints Conservation cheaper than generation Regulatory pressure

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Energy Efficiency Incentive Programs

How do these programs work? 1. Water or wastewater utility contacts their electrical utility to ask

for specific program details, and which program components apply to them.

2. A program representative conducts an energy audit or facilities plan analysis and determines which program components the facility can take advantage of.

3. As projects are completed, a program representative will perform measurements and verify savings.

4. The utility pays the industrial facility an incentive check based on the savings.

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Energy Efficiency Incentive Programs

Example Incentives: Oregon Bonneville Power Administration

Via rural electric co-ops $.25/kWh of annual savings Up to 70% of total project costs Energy management services

Energy Trust of Oregon $.32/kWh of annual savings Up to 50% of project costs

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Energy Efficiency: Incentive Example

Example Savings: BPA Incentive $.25 per kWh saved, based on first

year’s energy consumption.This is about $1600 per horsepower

on a 24/7 basis.Reducing pull on an aeration system

from 45 hp to 35 hp has a potential incentive of roughly $16,000 annually.

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Energy Efficiency Incentive Programs

How do I find incentives in my region?Contact your electric service providerEfficiency programs often handled by consultant

group, not utility directlyDatabase for State Incentives for Renewables

and Efficiency (DSIRE) http://www.dsireusa.org/

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More Efficiency Incentives

What about Tax Credits? Municipalities and Non-profit Districts don’t pay

taxesPrivate ‘pass-through partner’ may be recipient,

particularly with big renewable energy projects

University Extensions: Audits and Grants

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But wait, there’s more!

Ongoing energy savings for life of the measure. Often reduced maintenance cost from turning

off or turning down equipment. Aesthetic and comfort improvements – e.g.

better lighting, better HVAC.

Conservation: The gift that keeps on giving!

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Long-Term Savings

*Water & Wastewater Systems Optimization & Energy Management Technologies: BacGen Overview Brief . Northwest Energy Efficiency Alliance, 2007.

Energy Efficiency Technical Assistance

New Project No New Project

Design Complete Still Thinking Requests energy

efficiency TADoes not request

energy efficiency TA

Does design reflect most

energy efficient solution?

Yes. Train on appropriate renewable

technologies and incentives

Encourage board to include

‘energy demand’ in

project selection criteria

Help board determine most

appropriate efficiency

measures and payback period

Contact local utility for

energy audit, or perform your own

Incorporate training on energy demands, costs, and potential

benefits to efficiency measures

No. Contact electric utility to evaluate design,

potential for energy savings and incentives

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Renewable Energy Opportunities

Solar Wind Hydro Biogas Heat pump

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Solar

Photovoltaic cells about 10% efficient, but “fuel” is free

“Tracking” systems much more efficient than fixed systems, but roof space is wasted space, so it might not matter

4 acres of tracking panels = 1MW Payback best where electricity is at least

$.10/kWh

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Wind

Small systems exist Payback best where electricity is at least

$.10/kWh 20 year payback common

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Micro-Hydro

Low-head and High-head systems available Relatively small footprint Micro-hydro opportunities on source water

intakes and effluent outfalls

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Digester Biogas

Can add algae or FOG to generate more methane

May qualify for Carbon Credits Cogenerators simple and common Fuel Cells

Most efficient; generate DC power 24/7; Minimal O&M Robust incentives Must condition fuel to remove Hydrogen Sulfide –

expensive on small scale Only viable above ~10 MGD

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Fuel Cell

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Heat Pumps

Capture heat from air, digesters or effluent Cheap energy

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Greywater and Effluent Reuse

Greywater Benefits Lower fresh water use Decreased water burden

to WWTP Dry season landscape

watering Potential groundwater

recharge Effluent is potential

revenue

Greywater Obstacles Permitting - Regulations

vary by state Diaper washing causes

contamination concerns Potential decreased

contribution to river flow High capital costs for

greywater systems

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Compost

Biosolids as Soil AmendmentClass ‘B’ worth up to $35/tonClass ‘A’ up to $30/yard

Can be expensive to make. Often must add bark, sawdust, sand, etc.

But may save considerably on landfill disposal fees

Must do more than meet standards – must make a marketable project

TAGRO:

http://www.cityoftacoma.org/page.aspx?nid=306

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Resources

http://www.energy.ca.gov/process/water/eff_water.html

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Resources

Database for State Incentives for Renewables and Efficiency (DSIRE) http://www.dsireusa.org/

RCAC Green Infrastructure Guide:http://www.rcac.org/assets/green_infra/gig.pdf

Thanks for listening about energy efficiency and renewables!