Fishbeck, Thompson, Carr & Huber, Inc.
Insight into Energy Savings at
Your WWTP:
The Good, the Bad,
and the Ugly
John Eberly, P.E. and
Erin Szczegielniak, P.E.
Fishbeck, Thompson, Carr and Huber, Inc.
Overview:



Introduction
Resources for beginners
Case studies
 Energy
audits
 Cost/benefit analysis
 Impact of electric rates
Introduction: Why are we here?

Energy and sustainability drivers

WWTP: cost drivers ($$$)
Introduction: Why does it matter?

Utility vs. general fund
 Enterprise
 General

fund – users pay fees
fund – taxes are levied
Why not just pass the costs on?
Introduction:
Where it makes a difference

Michigan populations are shrinking.

Water and sewer
 Aging
plants will require capital.
 Energy costs rising.

City initiatives: cut costs 10 to 20%

Energy savings interest us all.
Resources for Beginners

WE&T articles:
 July
2011 „Energy sense‟
 “What
you know can save you”
 “Powerful predictions”
 December
 “Small
2011
changes add up to big savings”
Resources for Beginners
Energy Star – Portfolio Manager
 Department of Energy
 Best practices, recognition, free tools
 www.energystar.gov
 Benchmarking
and comparison
 Water/wastewater utilities – NEW
Resources for Beginners
www.energystar.gov
Improvement - What’s the
Process?
Benchmarking
Facility audit
Process audit
Retro-commissioning
O&M (operations and maintenance)
ECM (energy conservation measures)
So You’re Serious About Saving Energy:

Energy audits
 Generate

Cost/benefit analysis
 What‟s

ideas
right for your WWTP?
Electric rates
 How
it makes a difference
Energy Audits: What is Your Focus?


Energy audit: broad look at the whole system
Reasons:
 Electricity
or fossil fuel reduction
 Grant conditions
 Operations costs
 Long-term planning – efficiency
Audit Levels

ASHRAE Level I
 Benchmarking,

ASHRAE Level II
 Adds

walkthrough, observations
deeper analysis
Process audit
 Delves
into treatment
ASHRAE Audits – The Usual Suspects

Lighting
 Retrofits
 Controls

HVAC
 Upgrades
 Controls

Envelope
 Insulation
 Sealing
Energy Audit: Example
Community-wide system
 Equipment locations:
Water lift stations
 Retention treatment basins


Occupied/equipment locations:
Wastewater pump stations
 WWTP


Occupied locations:
Water system office
 Maintenance building

Energy Audit: Example
Equipment locations:
 Operations:
 Adding
elevated storage tank
 DO (dissolved oxygen) control of aeration tanks

Large equipment, high run times:
 Premium
efficiency motors
 VFDs (variable frequency drives)
 Pump efficiency – design curve vs. operation
Energy Audit: Example
Occupied locations:
 Light bulbs
 Incandescent
to CFLs, fluorescent T-12 to T-8
 Occupancy sensors


Repairing exterior doors
Heating:
 High-efficiency
furnaces
 Replace gas-fired hot water boiler
Energy Audits:
Lessons:

There are always opportunities.

An estimate, not a guarantee.

Starting place – sometimes need more
information.
Cost/Benefit Analysis:
Good Idea, Bad Idea?

Closer consideration

How to tell what‟s right for:
 Your
plant
 Your staff
 Your community

Further investigation
Cost/Benefit Analysis: Example
Equipment replacement = opportunity
for new technology
Ex. Aeration: coarse bubble diffusers
Considering: fine bubble diffusers
(+) More efficient air transfer
(+) Lower blower horsepower
(-) More maintenance
Cost/Benefit Analysis:
What You Need to Know
 Capital
 Make
costs:
a fair assessment.
 Would
 Look
 Do
these need to be replaced soon anyway?
at ancillary costs.
existing systems work with the new technology?
Cost/Benefit Analysis:
What You Need to Know
 Maintenance
 Hidden
 Staff
costs:
costs?
availability?
 Funding
 Return
on investment: what‟s the acceptable risk?
Cost/Benefit Analysis: Example
Result:
Kept existing coarse bubble diffusers



Return on investment – too high.
High capital investment and maintenance.
Still an estimate.
Cost/Benefit Analysis:
Lessons:
 Each plant has site-specific needs and
considerations.


Energy is one of many cost factors.
What‟s wrong for Plant A,
may be right for Plant B.
Electric Rates: Look at Your Assumptions
Equipment replacement may look good on
paper.
Preliminary estimates use a flat rate:
$0.07-0.09/kWh
Reality: most WWTPs have a tiered rate
structure that can change the results.
Electric Rates: Example
Plant A pays $22,500/month for 230,000 kWh

Average cost: $0.096/kWh

Equipment Change: Estimating 20% Energy
savings (46,000 kWh/month)
HOW MUCH $$ WILL THEY SAVE?
Electric Rates: Example
Electric Bill – (simplified) break down
Charges
Rate ($/kWh)
Access Fees
Cost
$6,700
First 50,000 kWh
$0.10
$5,000
Next 180,000 kWh
$0.06
$10,800
TOTAL
$22,500
Electric Rates: Example
20% savings (46,000 kWh): All at $0.06/kWh
Charges
Rate ($/kWh)
Access Fees
Cost
$6,700
First 50,000 kWh
$0.10
$5,000
Next 180,000 kWh
$0.06
$10,800
TOTAL
$22,500
Electric Rates: Example
Plant A reduces energy use by 20%:
Only 7.3% Cost Savings
550,000 kWh /year
Rate ($/kWh)
Annual Savings
Estimated
$0.096
$52,800
Actual
$0.060
$33,000
DIFFERENCE
$19,800
Electric Rates: Know Your Assumptions
Not all bad:
 Still saving $33,000 per year.
Lesson: If you need precise estimates, use
precise assumptions.
Electric Rates: Know Your Assumptions
Communication is key.
Talk to your engineer or other energy assessor.
Make sure they understand the realities of your
facility.
Energy Savings: What Did We Learn?
What‟s best for YOUR PLANT isn‟t always
obvious.
There are different tools available to help.
 Energy audits
 Cost/benefit analysis
 Risk-appropriate assumptions
 Good communication
Questions?
Erin Szczegielniak
•248-324-1582
•[email protected]
John Eberly
•616-464-3853
•[email protected]
Happy Savings!