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Reducing Energy Costs in Water and Wastewater Treatment Systems

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Presentation on theme: "Reducing Energy Costs in Water and Wastewater Treatment Systems"— Presentation transcript:

1 Reducing Energy Costs in Water and Wastewater Treatment Systems
Cory Johnson, P.E. CH2M HILL Eastern US Practice Lead for Water Treatment, Membranes, and Reuse 550 W Cypress Creek Rd Suite 400 Fort Lauderdale, FL

2 Managing Energy Improves Sustainability while Reducing O&M Costs
Energy costs are rising Annual energy cost of: A Florida utility was $5.2M (2005) operating one WWTP (>30mgd) and 4 WTPs (ranging is size from 14 to 30 mgd) A Georgia utility was ~$5.5M per year to operate two WTPs (170 mgd total capacity) A 5% to 10% energy cost savings could result in of $250k to $500k annual savings

3 Energy Audit, Energy Management?
Energy Management Studies are not just ‘electrical’ Energy efficiency evaluation process is a multi-disciplinary task Evaluation team should include Process, Electrical, I&C, and HVAC Engineers, Operational Specialists, and Economists Energy costs are a function of electrical, process, operations, and controls --- and economists!

4 Water Plant Energy Management
Pumping is typically ~90% of water system energy use Ways to save energy cost: Operational Optimization Chemical Energy Operational and Capital Improvements Rate Structures

5 Example where Smarter Operations Resulted in Significant Savings
Distribution system hydraulic model used to refine the existing operating plan to meet more strict water quality regulations and minimize operating costs for a 10 mgd system 25% reduction in energy cost with Energy Market rate and revised pump controls and operations

6 How to Perform an Energy Management Study

7 Steps to Perform an Energy Management Study
Task 1: Project Kickoff and Chartering Task 2: Pre-Site Visit Review (Homework) Review plant specific data Familiarize with current operational procedures and control strategies Analyze electrical bills Evaluate plant electrical one-line diagrams Identify major energy intensive processes (pumping, generation technologies, UV disinfection, blowers, HVAC, lighting) Generate preliminary list of ideas for energy saving measures Task 3: Facility Evaluations (Site Visits) Interview plant operational staff Verify motor name plate data and confirm ‘run time’ on motors Review processes which can be shifted to ‘off peak’ hours Discuss and review control strategies for energy intensive processes Review rate structures with operational staff

8 Steps to Perform an Energy Management Study (cont’d)
Task 4: Data Evaluation and Modeling Create a baseline energy usage model Simulate existing plant operation and energy usage to calibrate Run ‘what if’ scenarios by simulation of process and pumping various operating conditions Evaluate control modifications to assess potential energy savings For energy saving opportunities that require capital expenditures, compute: Capital Cost Annual Energy Savings Payback period Estimate energy savings from shifting operations to ‘off-peak’ Recommend electrical modifications to take advantage of rate structure Task 5: Report Preparation Task 6: Final Workshop and Presentation

9 Areas of Focus during Assessment
Evaluate the energy rate structure Identify peak and off-peak periods and any power factor penalties Investigate feasibility of installing power factor improvement capacitors Evaluate installation of energy monitoring equipment which can be interfaced into the SCADA system Evaluate lighting to recommend ways to save energy by better control of lighting circuits Recommend improvements in the electrical systems that would improve efficiency, reliability, and safety Investigate major pumping systems Evaluate all plant treatment processes Evaluate HVAC systems

10 Categorization of Assessment Recommendations
Summarize and categorize each recommendation with “pros and cons” for each category Category #1: “Low Hanging Fruit” Can be almost immediately implemented No capital cost Reasonable energy savings Category #2: Actions requiring minimum to moderate capital investment with payback of 1 to 5 years Category #3: Actions that may require significant capital investment, but could pay back in 5 to 7 years

11 Water and Wastewater Plant Assessment Examples

12 Example Water Treatment Plant Process Flow
Transfer Pumping Media Filtration Softening Aeration Well Pumping To Storage & High Service Pumping Sand Strainers Cartridge Filters Membrane Softening Aeration/ Degasification

13 Energy Audit Results at WTPs Example: Lime Softening and Ozone
Recommendation Estimated Annual Savings Cost of Improvement Estimated Pay Back Period Category Ozone Operation $ 5,600 $ 16,000 2.8 Category II Converting to LOX $ 65,000 $ 165,000 3.1 Category III High Service pump $ 28,000 $ 0 Category I Motion sensors $ 800 $ 1,600 2 TOTALS $ 99,400 $ 182,600 19

14 Energy Audit Results at WTPs Example: Membrane Softening
Recommendation Estimated Annual Savings Cost of Improvement Estimated Pay Back period Category Membrane Operations $ 16,500 $ 0 Category I Degasifier Operations $ 11,415 Concentrate / IW #3 $ 21,300 $ 90,000 4.4 Category III TOTALS $ 49,215 21

15 Examples of Energy Audit Results at WTPs
Pump sizing vs. valve throttling 25 well pumps (75 to 100 hp) Discharge valves throttled to maintain well drawdown and reduce pressure to match RO facility requirements 2.7 million kW-hr of additional energy used ---- additional $150,000 in annual energy costs Program implemented to replace all the pumps with 40 to 50 hp motors with AFDs OSHG Programming Logic Modifications Modified programming logic to change generation time from peak hours of 12pm to 9pm to off peak hours of 12am to 9am $18k annual cost savings 23

16 Efficient Pump Combinations
BEP $$

17 Wastewater Pump Station Analysis – Operational Changes
15 MGD system Review pump curve efficiencies, power draw, runtimes, and energy bills Recommended alternate operating scenarios for pump station to maximize existing efficiency Analysis of cost for running one pump versus two pumps at 70% or 80% capacity. Identified that to pump the same amount of water, it can cost 50% less using two pumps versus one, in 30% less time. Results vary based on pump curves.

18 FOG and Codigestion

19 What is Codigestion? Direct addition of high-strength organic wastes to municipal wastewater anaerobic digesters Typical high-strength organic wastes Fats, oils, and grease (FOG) Restaurant food scraps Food processing wastes Off-spec cola syrups Dairy wastes Cheese Wastes Brewery Wastes Winery Wastes Others 19

20 Advantages of Codigestion
Technical Removes FOG from sewer collection systems Removes FOG materials from headworks and primary clarifiers Removes organic loadings on liquid treatment train Increases digester utilization Economic Produces more biogas for beneficial uses (CHP, dryer, vehicles, etc.) New revenue streams from tipping fees Reduces O&M costs for headworks and liquid treatment trains Environmental Reduces landfilling of high-strength wastes (HSW) Reduces emission of greenhouse gases

21 Challenges of Codigestion
Possible need for digester upgrades Additional capital and O&M costs for FOG/HSW receiving and processing Additional paperwork for permitting, waste receipts, billings Debris removal and disposal Potential negative anaerobic digester performance impacts Potential anaerobic digester toxicity from HSW Potential increase in nutrient concentrations in sidestreams

22 Johnson County, Kansas Middle Basin WWTP – 12. 5 mgd (14
Johnson County, Kansas Middle Basin WWTP – 12.5 mgd (14.5 mgd Capacity)

23 FOG/HSW are blended sequentially with primary sludge and thickened WAS
Process Flow Diagram FOG/HSW are blended sequentially with primary sludge and thickened WAS

24 Project Financials Capital cost of codigestion and cogeneration Improvements $10,000,000 Annual FOG/HSW tipping fee revenue $300,000 Annual electrical power from biogas $400,000

25 Alternative Financing through Performance Contracts

26 Performance Based Contracts with Energy Services Companies
Energy Service Company (ESCo or ESCO) based project (certification required) ESCO has become a generic term for Energy Performance Contracts Started in 1970s with lighting, developed in 1980s with hospitals and matured in 1990s with buildings (HVAC, lighting, building energy management) Today moving from buildings to all aspects of energy efficiency (street lighting, traffic control, water and wastewater operations) International Performance Measurement and Verification Protocol (IPMVP) used to measure before and after energy use Typically use “Performance Contracting” to finance and implement projects as part of a Guaranteed Energy Performance Contract (GEPC) Finance is normally from the private sector

27 Guaranteed Energy Performance Contracting (GEPC)
GEPC evaluates a project or a program and develops an agreement with a fixed (guaranteed) capital cost and operational savings for the program Much like a Design Build agreement Added in is the energy performance guarantee Methods of capital investment Utility floats bond based on program value (not common) Outside financing Inside financing The contractor capital or the bond is paid back with savings from program (e.g., shared savings concept) Government regulated terms and conditions usually 10 to 20 year term for payback (formal ESCO) GEPC Contractor financed projects normally self limited to investment in projects with 3 to 10 year payback

28 Services Covered by Energy Performance Contracting
Anything related to energy or green related savings including: Standard Energy Conservation Measures – Lights, traffic lights, HVAC controls, etc. Non-revenue water reduction Bio-solids reduction Digester gas to energy production Water metering – reduction of non-revenue water Pumping savings (water distribution, wastewater collection) Distribution system optimization Wastewater treatment mechanical upgrades (e.g., blowers) and process upgrades Adding renewable energy to the utility’s portfolio (normally blended approach) Energy procurement strategies to reduce overall energy costs

29 Driving Factors for a Energy Performance Contract
Driving Factors for Convention Project Approach Utility does not have financial capacity (e.g., lacks bonding capacity) Utility wants to holistically look at their energy consumption and carbon footprint Utility knows that there is a project but not sure of the details or how to finance Risk Transfer Utility has financial capacity Utility knows exactly what project they want – no variables Limited Project Risk

30 Case Study - Wilmington, DE – Operational and Capital Improvements with ESCO Funding
Wilmington serves 100,000 people MGD Cash strapped city with big “Green” expectations Period of performance is 20 years as per Delaware state ESCO law Program designed to: Reduce energy and operational costs Reduce GHG emissions Insulate the City from future electricity and biosolids cost escalation through renewable energy generation and sludge volume reduction

31 Phase 1 of the program includes city‐wide energy conservation measures, peak demand reduction and solar  generation Over $400,000 in annual net savings through renewable generation, energy use reduction and energy price reduction Approximately $180,000 of construction period savings have already been realized The City has received national recognition for its successful deployment of ARRA stimulus funds for renewable energy and infrastructure improvement

32 Phase 2 intended to provide a long term biosolids management solution
Cogeneration of inexpensive renewable fuel (methane) will supply plant electric demand and heat for thermal drying of biosolids Thermal drying will reduce biosolids volume by over 80% and eliminate cost and regulatory uncertainties associated with off-site trucking/land application Combined, both phases result in 50% of City’s energy demand supplied by renewable generation and achievement of 20% greenhouse gas reduction goal under the Climate Protection

33 Closing Thoughts

34 Summary Water and Wastewater Treatment Continue to Increase in Energy Intensity As water quality regulations become tighter, kW-hr/MG increases Significant Opportunities to find Energy Savings in Plants and Piping Systems Energy management studies are a multi-disciplinary effort and focused on more than just ‘electrical’ Level of effort can be tailored to specific studies

35 Summary Holistic plant optimization studies can incorporate chemical feed optimization FOG programs represent a potential revenue source and additional fuel source when considering codigestion ESCOs and GEPCs can bring funding for projects using energy savings 25

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