Energy Efficiency for Water and Wastewater Systems

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Energy Efficiency for Water and Wastewater Systems
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Welcome

• Trainer
• Jake Salcone
• RCAC Portland, OR
• Rural Development Specialist Environmental
• Event
• Washington D.C. RCAP conference
• December 2010

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Why Energy Efficiency?

• Some 4 of the nations 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 TreatmentThe Next
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 distribution
• Cost of power
• Capacity 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
• II reduction is an efficiency measure
• Basic systems use less energy

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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/II 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?
• Water or wastewater utility contacts their
  electrical utility to ask for specific program
  details, and which program components apply to
  them.
• A program representative conducts an energy audit
  or facilities plan analysis and determines which
  program components the facility can take
  advantage of.
• As projects are completed, a program
  representative will perform measurements and
  verify savings.
• 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 years 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 provider
• Efficiency programs often handled by consultant
  group, not utility directly
• Database 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 dont pay
  taxes
• Private pass-through partner may be recipient,
  particularly with big renewable energy projects
• University Extensions Audits and Grants

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But wait, theres 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.
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• Energy Efficiency Technical Assistance

New Project
No New Project
Design Complete
Still Thinking
Requests energy efficiency TA
Does not request energy efficiency TA
Does design reflect most energy efficient
solution?
Encourage board to include energy demand in
project selection criteria
Contact local utility for energy audit, or
perform your own
Incorporate training on energy demands, costs,
and potential benefits to efficiency measures
Yes. Train on appropriate renewable technologies
and incentives
No. Contact electric utility to evaluate
design, potential for energy savings and
incentives
Help board determine most appropriate efficiency
measures and payback period
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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
  OM
• 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 Amendment
• Class B worth up to 35/ton
• Class 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?nid306

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Resources
http//www.energy.ca.gov/process/water/eff_water.h
tml
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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!