The City of San Diego Metropolitan Wastewater Department’s Sustainable Energy Management Using In-House Resources

The City of San Diego MWWD Serves 2.2 million peopleServes 2.2 million people Treats an average of 180 MGDTreats an average of 180 MGD Has a peak flow of 477 MGDHas a peak flow of 477 MGD Operates four Treatment Plants and 90 Pump StationsOperates four Treatment Plants and 90 Pump Stations Treats Wastewater for 15 Cities

Metropolitan Wastewater System Existing & Planned Facilities

The Facilities Consist of: One 240 MGD Advanced Primary WWTPOne 240 MGD Advanced Primary WWTP Two Water Reclamation Plants (30 & 15 MGD)Two Water Reclamation Plants (30 & 15 MGD) One 150 DTD Biosolids Processing FacilityOne 150 DTD Biosolids Processing Facility And, Pump Stations with Pumps from 3 HP to 2250 HPAnd, Pump Stations with Pumps from 3 HP to 2250 HP

Renewable Energy In 2006 the City of San Diego consumed more renewable energy than any other agency in the U.S. (Average: 7.2 MW)In 2006 the City of San Diego consumed more renewable energy than any other agency in the U.S. (Average: 7.2 MW) MWWD consumes 96% of that green energyMWWD consumes 96% of that green energy MWWD currently produces or causes to produce more than twice than is consumes (16.6 MW MW)MWWD currently produces or causes to produce more than twice than is consumes (16.6 MW MW)

Point Loma Wastewater Treatment Plant 4.53 MW DIGESTER GAS BASE MW PEAKING 1.35 MW HYDRO DIGESTERS FLARES PRIVATIZED BUDG 300 KW FUEL CELL MW FUEL CELLS OFFSITE (BOC)

PLWTP Hydroelectric Generator

Duel Fuel A ENGINE AIR CLEANER DIGESTER GAS POWER FUEL/AIR MIXER TURBO CHARGER DIESEL FUEL INJECTION GENERATOR

LFG & Digester Gas

Landfill Gas Well

MBC COGEN 6.4 MW PRIVATIZED COGENERATION FACILITY (MINNESOTA METHANE)

Cogen System Schematic

NCWRP NCCF 3.8 MW PRIVATIZED (MINNESOTA METHANE)

MWWD 30kW Photovoltaic System at MOC III 30 kW rooftop system at MOC III Under directive from Metro Commission, innovative rooftop mounting system and semiconductor technology were chosen

Solar Cadmium Telluride Use of the First Solar’s cadmium telluride thin film collectors helps to push the Photovoltaic Industry’s development by using new Mass Produced Technologies for PV cells that have a strong potential of obtaining SIGIFICANTLY LOWER COSTS PER WATT INSTALLED in the near future.Use of the First Solar’s cadmium telluride thin film collectors helps to push the Photovoltaic Industry’s development by using new Mass Produced Technologies for PV cells that have a strong potential of obtaining SIGIFICANTLY LOWER COSTS PER WATT INSTALLED in the near future. This installation also utilized new mass produced PVC flat ballast mounted roof racks.This installation also utilized new mass produced PVC flat ballast mounted roof racks. Other Benefits Include: Better performance on cloudy days And may include: Lower performance lost over the life of the collectorOther Benefits Include: Better performance on cloudy days And may include: Lower performance lost over the life of the collector

Energy Produced per Rated kW per Day – August 2003 MOC IIIMiramarRidgehaven /1/038/6/03 8/11/038/16/038/21/038/26/038/31/03 Date kWh per rated kW per Day 20% Higher Average Production/Rated kW CdTe vs. Si

BUDG BOC/Linde System Diagram Point Loma BUDG Purification System 3 Off-site Fuel Cells, 1.2 MW’s each Blower Sulfur Removal Drying, Chilling, Purification beds 2-Stage Compressor Membrane CO 2 Removal 3-Stage Compressor Fuel Cell CNG Enclosed CO 2 Flare

Point Loma BUDG Schematic Compressed Digester Gas to Truck 3-Stage HP Compressor Feed from PLWTP Gas System Flare 0 psig 5 psig 0 psig 165 psig Blower Pre-PSA Dryer Refrigeration Pressure Swing Absorption (PSA) Dryer 2-StageCompressor Pre-Granular Activated Carbon Refrigeration Granular Activated Carbon Filter Pre- Membrane Heater 150 psig 140 psig 2600 psig C02 Removal Membrane Unit Condensate Return to Wastewater Plant C0 2 Sulfur Removal Fuel Cell

Energy Engineering

Develop and manages power production projectsDevelop and manages power production projects Reviews new designs and obtains grants for energy efficiencyReviews new designs and obtains grants for energy efficiency Fostered the writing of the Department’s energy planFostered the writing of the Department’s energy plan Leads the energy audit teamLeads the energy audit team Takes the lead on the implementation on non- operational energy projectsTakes the lead on the implementation on non- operational energy projects Track Department’s energy dataTrack Department’s energy data MWWD Energy Section Point Loma Hydro

Energy Audits Engineering, O&M and interested othersEngineering, O&M and interested others Trained with CEC GrantTrained with CEC Grant Three to four audit reports per yearThree to four audit reports per year 19 reports completed19 reports completed

NRG AUDITS 169 potential improvements169 potential improvements 44 improvements implemented44 improvements implemented 20 in progress20 in progress 93 pending proposals/ additional analysis93 pending proposals/ additional analysis Examples:  Turn off 800hp back up blower  Program to eliminate air gap system - 1 pump station completed  Automate and raise large pump station wet well set point  VFD on 60hp ventilation fan  Lighting  VFD on cooling water pumps

Coming Attractions 900 KW expansion of the NCCF900 KW expansion of the NCCF 6.3 MW of peaking emergency generation for free generator maintenance6.3 MW of peaking emergency generation for free generator maintenance 1 MW Photovoltaic System1 MW Photovoltaic System NEW Department Annual Energy Conservation Budget with performance guidelinesNEW Department Annual Energy Conservation Budget with performance guidelines Energy audit suggestions implemented through Non- Profit contractor with Energy Incentives from utilityEnergy audit suggestions implemented through Non- Profit contractor with Energy Incentives from utility Automated flow pace control of PLWTP HydroAutomated flow pace control of PLWTP Hydro