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 fund users pay fees General 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 2011 Small 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 ideas Cost/benefit analysis What s 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, walkthrough, observations ASHRAE Level II Adds 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
Capital costs: Cost/Benefit Analysis: What You Need to Know Make a fair assessment. Would these need to be replaced soon anyway? Look at ancillary costs. Do existing systems work with the new technology?
Cost/Benefit Analysis: What You Need to Know Maintenance costs: Hidden costs? Staff 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) Cost Access Fees $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) Cost Access Fees $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 ehszczegielniak@ftch.com John Eberly 616-464-3853 jreberly@ftch.com Happy Savings!