The City of San Diego Metropolitan Wastewater Department s

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

The City of San Diego MWWD Treats Wastewater for 15 Cities • Serves 2. 2 million people • Treats an average of 180 MGD • Has a peak flow of 477 MGD • Operates four Treatment Plants and 90 Pump Stations

Metropolitan Wastewater System Existing & Planned Facilities

The Facilities Consist of: • One 240 MGD Advanced Primary WWTP • Two Water Reclamation Plants (30 & 15 MGD) • One 150 DTD Biosolids Processing Facility • And, 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) • MWWD consumes 96% of that green energy • MWWD currently produces or causes to produce more than twice than is consumes (16. 6 MW + 3. 9 MW)

Point Loma Wastewater Treatment Plant 4. 53 MW DIGESTER GAS BASE + 1. 2 MW PEAKING DIGESTERS FLARES PRIVATIZED BUDG 300 KW FUEL CELL + 3. 6 MW FUEL CELLS OFFSITE (BOC) 1. 35 MW HYDRO

PLWTP Hydroelectric Generator

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

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 30 k. W Photovoltaic System at MOC III • 30 k. W 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. • 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 collector

8 20% Higher Average Production/Rated k. W Cd. Te vs. Si 6 4 2 Date Ridgehaven Miramar MOC III 3 31 /0 8/ 8/ 26 /0 3 3 21 /0 8/ 3 16 /0 8/ 3 11 /0 8/ 03 6/ 8/ 1/ 03 0 8/ k. Wh per rated k. W per Day Energy Produced per Rated k. W per Day – August 2003

Blower Sulfur Removal Drying, Chilling, Purification beds BUDG BOC/Linde System Diagram 2 -Stage Compressor CNG Enclosed CO 2 Flare Membrane CO 2 Removal 3 -Stage Compressor Fuel Cell Point Loma BUDG Purification System 3 Off-site Fuel Cells, 1. 2 MW’s each

Point Loma BUDG Schematic C 02 5 psig 0 psig Feed from PLWTP Gas System Sulfur Removal 0 psig 165 psig Pre-PSA Dryer Refrigeration 2 -Stage Compressor Blower Pressure Swing Absorption (PSA) Dryer Pre-Granular Activated Carbon Refrigeration Condensate Return to Wastewater Plant 2600 psig Compressed Digester Gas to Truck 140 psig 3 -Stage HP Compressor Fuel Cell C 02 Removal Membrane Unit 150 psig C 02 Pre. Membrane Heater Granular Activated Carbon Filter Flare

Energy Engineering

MWWD Energy Section • Develop and manages power production projects • Reviews new designs and obtains grants for energy efficiency • Fostered the writing of the Department’s energy plan • Leads the energy audit team • Takes the lead on the implementation on nonoperational energy projects • Track Department’s energy data Point Loma Hydro

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

NRG AUDITS • • 169 potential improvements 44 improvements implemented 20 in progress 93 pending proposals/ additional analysis Examples: § Turn off 800 hp 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 60 hp ventilation fan § Lighting § VFD on cooling water pumps

Coming Attractions • 900 KW expansion of the NCCF • 6. 3 MW of peaking emergency generation for free generator maintenance • 1 MW Photovoltaic System • NEW Department Annual Energy Conservation Budget with performance guidelines • Energy audit suggestions implemented through Non. Profit contractor with Energy Incentives from utility • Automated flow pace control of PLWTP Hydro