Municipal Wastewater Treatment Preliminary Seventh Power Plan Energy Efficiency Estimates October 14, 2014 West Point Wastewater Treatment Plant, Seattle Washington

Municipal Wastewater Industry in the PNW Over 1100 Plants use 140 aMW of Energy – Sixth Plan: 893 plants, 137 aMW Processes Include – Collection – Treatment Sludge Processing & Disposal – Discharge Picture from: Arkansas Watershed Advisory Group

The Many Factors that Affect Plant Energy Consumption Influent Biological Oxygen Demand (BOD) Effluent BOD Weather/Location MGD design capacity MGD flow Primary Clarifier Effectiveness Secondary Treatment Process Type – Activated Sludge Coarse or fine bubble aeration Dissolved Oxygen control method – Aerated Lagoon Dispersed Aeration or Mechanical Aeration Varying amounts of aeration – Trickle Filter – Disinfection method (Chlorine or UV) Tertiary Treatment Process Type Sludge Treatment Processes – Dewatering method – Digestion Onsite Generation (IC Engine or Micro-Turbine Using Digester Gas, Micro-Hydro at discharge, etc.) Lebanon, OR

Energy Savings Measures – VFDs – Upgrade to premium efficiency motors – Aeration blower control via automated dissolved oxygen monitoring – Fine bubble diffusers – Optimize pumping and blower configurations and operation/controls – Upgrade to more efficient pumps and blowers – Use hydraulic digester mixing & optimize mixing time DO Control from wateronline.com Blower from spenserturbine.com Fine Bubble Diffusters from sequencertech.com

Sixth Plan Summary Technical Potential: 36.0 aMW (for reference, the Fifth Plan technical potential was 65 aMW) Achievable potential at a levelized cost of $16/MWh. Achievements since Sixth Plan From the BPA Six Going on Seven Project: – Savings = 6.07 aMW (2010 – 2012, approximately 2 aMW per year) – Well aligned with 6P ramp rates – Assume 10 aMW for

Energy Variables Baseline – Number of WT facilities – EPA 2008 data (6P was 2004 data) – Treatment flow (Million Gallons per Day, MGD) – EPA 2008 – Energy Consumption(Million kWh/MGD) – same as Sixth Plan Growth – Council population forecast Assume a 0.5% annual increase in efficiency – from Sixth Plan EE potential (kWh/MGD) – same as Sixth Plan Saturation – From BPA “Six Going on Seven” project (6 aMW , assume 10 aMW through 2014)

Proposed Changes To Savings Sixth Plan Assumptions Sub CategoryCount Sum Capacity (MGD) Sum Flow (MGD) Avg Flow (MGD) Annual energy use/Volume (mmkWh/ MGD flow) Total Wastewater Consumption (MWa) Estimated Savings (million kWh/MGD flow) Estimated Total Savings Potential (aMW) Estimated Average Savings Rate (%) Average Facility use (kWh) Average Facility Savings (kWh) <1 MGD % 330, , MGD % 1,896, ,355 >10 MDG401,4791, % 16,172,843 1,768,800 All 8932,2081, Proposed Seventh Plan Assumptions – Net of Accomplishments <1 MGD % 278, , MGD % 1,770, ,345 >10 MDG351,3101, % 17,273,572 1,404,645 All1,1502,2161, Savings values adjusted for achievements

Cost Variables Measure cost – Sixth Plan, adjusted for 2012$ – Recent project experience and data for first-year cost - $0.41/kWh (Cascade data), $0.71/kWh (Energy Trust) – Not enough variation by size O&M Cost/Benefit – Used Sixth Plan values, adjusted to 2012$ – Source was NYSERDA study 2006 (Detailed O&M benefits and costs for 11 sites)

Proposed Changes To Costs Sub Category Measure Cost ($/kWh) O&M and NEB's ($/kWh) Average Facility Measure Cost Average Facility Annual O&M and NEB's Measure Cost per MGD Flow O&M and NEB per MGD Flow <1 MGD $ 0.49 $ 0.03 $ 99,558 $ 5,594 $ 637,762 $ 35, MGD $ 0.57 $ 0.03 $ 360,276 $ 17,583 $ 164,322 $ 8,019 >10 MDG $ 0.20 $ 0.03 $ 360,838 $ 49,027 $ 13,167 $ 1,789 Sub Category Measure Cost ($/kWh) O&M and NEB's ($/kWh) Average Facility Measure Cost Average Facility Annual O&M and NEB's Measure Cost per MGD Flow O&M and NEB per MGD Flow <1 MGD $ 0.55 $ $ 69,107 $ 3,883 $ 525,094 $ 29, MGD $ 0.63 $ $ 276,938 $ 13,515 $ 135,293 $ 6,603 >10 MDG $ 0.23 $ $ 317,311 $ 43,113 $ 10,841 $ 1,473 First Year Cost Notes: - Cascade database: $0.41/kWh (N=105) - Energy Trust: $0.71/kWh (N=21) Adjusted measure and O&M cost for 2012 dollars, from 6P 2006 dollars

Summary and Next Steps Summary – Achievable potential approximately 28 aMW – Preliminary levelized costs approximately $12/MWh RTF Input – Finalize with existing data or is more research needed?