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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
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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 • 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 Fine Bubble Diffusters from sequencertech.com Blower from spenserturbine.com DO Control from wateronline.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 $16/MWh. Achievements since Sixth Plan • From the BPA Six Going on Seven Project: • Savings = 6.07 aMW (2010 – 2012, approximately 2 aMW per year) • Well aligned with 6P ramp rates • Assume 10 aMW for 2010 - 2014
Energy Variables • Baseline • Number of WT facilities – EPA 2008 data (6P was 2004 data) • Treatment flow (Million Gallons per Day, MGD) – EPA 2008 • Energy Consumption(Million kWh/MGD) – same as Sixth Plan • Growth – Council population forecast • Assume a 0.5% annual increase in efficiency – from Sixth Plan • EE potential (kWh/MGD) – same as Sixth Plan • Saturation – From BPA “Six Going on Seven” project (6 aMW 2010-2012, assume 10 aMW through 2014)
Proposed Changes To Savings Savings values adjusted for achievements
Cost Variables • Measure cost • Sixth Plan, adjusted for 2012$ • 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 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?