Princeton University Microgrid IDEA evolvingenergy Conference Toronto, Canada 28th 30th October 2014 Edward Ted Borer, PE etborer@princeton.edu
Overview Campus Energy Demands Energy Plant Equipment Combined Heat and Power Production Plant Economic Dispatch Historic & Projected Emissions Solar PV Microgrid issues Water Sources & Use Continuing Opportunities
Energy Demands at Princeton > 180 Buildings Academic Research Administrative Residential Athletic
Energy Equipment & Peak Demands Electricity Rating Peak Demand (1) Gas Turbine Generator 15 MW 27 MW Solar Photovoltaic System 5 MW Steam Generation (1) Heat Recovery Boiler 180,000 #/hr (2) Auxiliary Boilers @ 150 ea. 300,000 #/hr 240,000 #/hr Chilled Water Production (3) Steam-Driven Chillers 10,100 Tons (5) Electric Chillers 10,700 Tons 13,800 Tons (1) Thermal Storage Tank *peak discharge 40,000 Ton-hours 10,000 tons (peak)
Plant Energy Balance PSEG Electricity Solar PV Electricity Electricity Natural Gas Gas Turbine & HRSG Backpressure Turbines #2 Diesel Fuel Oil Biodiesel Fuel Oil Duct Burner & HRSG Auxiliary Boilers Chilled Water & Thermal Storage Systems Steam Chilled Water Campus Energy Users
HRSG & Auxiliary Boilers
HRSG & Auxiliary Boilers
Campus District Energy Systems
Centrifugal Electric Chiller
Chilled Water Thermal Storage Warm vapor Warm water from HTX or tank ~ 56 F Warm water from Campus ~ 58 F Cooling Tower Hot Chiller Thermal Storage Tank Cold water To Campus ~ 34 F Cool Cold water To HTX or tank ~ 32 F Plate & Frame Heat Exchanger
TES Tank Stratification
Total Chilled Water Flow Outdoor Temperature Princeton Chilled Water Use Campus Chilled Water Production, June 2002 22,000 110 20,000 100 18,000 90 16,000 80 14,000 70 12,000 60 10,000 50 8,000 40 6,000 30 4,000 2,000 Total Flow, gpm Outdoor Temp 20 10 0 0 10-Jun 11-Jun 12-Jun 13-Jun
Princeton Summer Steam Use 160 140 120 100 80 60 40 Steam Flow, M#/hr 20 Outdoor Temperature, F 0 22-Jun 23-Jun 24-Jun 25-Jun 26-Jun 27-Jun
Combined Heat & Power, Cogeneration Air Fuel & Water Gas Turbine Power Turbine Gearbox Electric Generator AC Electricity Hot exhaust Gas CO Catalyst Feed Water Heat Recovery Boiler Exhaust Gas Steam
How Much More Efficient is Combined Heat & Power?
The GE LM-1600 Gas Turbine
Megawatts. Princeton Power Demand With Cogen Dispatch To Minimize Cost 20 18 16 Generation Campus Demand Power Purchase 14 12 10 8 6 4 2 0-2 08 Jul 05 08 Jul 05 09 Jul 05 09 Jul 05 10 Jul 05 10 Jul 05 11 Jul 05
Princeton Economic Dispatch System PJM Electric Price NYMEX gas, diesel, biodiesel prices Biodiesel REC value & CO 2 value Current Campus Loads Weather Prediction Production Equipment Efficiency & Availability Business Rules Historical Data ICETEC Operating Display Historical Trends Generate/Buy/Mix Preferred Chiller & Boiler Selections Preferred Fuel Selections GT Inlet Cooling Mode Live feedback to Icetec ICAP & Transmission Warnings Operator Action
TES Economic Dispatch Screen
PSEG Generation Stack
Campus CO 2 Emissions by Source
Previous Energy Saving Projects Cogeneration Plant Lighting Retrofits VFDs Premium Efficiency Motors Central EMS Vending Misers Monitor Sleep Mode Condensate Recovery Energy Guidelines Backpressure Turbines Reverse Osmosis Cooling Tower Chemistry High Efficiency Chillers Hybrid Vehicle LCD Monitors Building Heat Recovery Thermal Energy Storage Retro-commissioning
Backpressure Turbine - Generators
Backpressure Turbines Heating steam is produced and distributed at 200 PSIG on campus. The pressure must be reduced to less than 15 PSIG when it enters a building. Pressure reduction is normally done by using control valves. Backpressure turbines reduce pressure and use that energy to turn small steam-turbine-generators. Princeton installed two backpressure turbines in Dillon Gym. They make 540 kilowatts at full power i.e., power for several buildings. $243,000 Smart Start grant for the use of new technology. Estimate $188,000 annual savings, < 4 year payback. Avoids 1270 metric tons of CO2 per year. Compact footprint of 3 feet x 11 feet.
Data Center Absorption Chiller 600 tons of cooling using only waste exhaust heat from a 1.9 megawatt gasfired reciprocating engine. It is the most efficient of it s type in the world. Princeton s will be the first gas-engine & absorption chiller combination used at a data center. Footprint: 11 feet x 20 feet
CO 2 Reduction Goals
Annual Chilled Water Use (Ton-Hours) Campus Floor Area (Sq.Ft.) Millions Millions Reduced Chilled Water Use 40 Princeton University Chilled Water Load Growth 10 35 30 Chilled Water Bldg Sq.Ft. 9 8 7 25 6 20 5 15 10 5 4 3 2 1 0 - Year
Campus Floor Area (sq.ft.) Millions Reduced Annual Steam Energy Princeton University Annual Steam Use Annual Steam Use (lbs) Millions 1,000 900 800 700 600 500 400 300 Steam Use Floor Area 10 9 8 7 6 5 4 3 200 2 100 1 0 - Fiscal Year
Princeton Solar PV 5.3 MW DC 27 Acres Lease equipment Own all power and Solar Renewable Energy Credits from day one Sell SRECs until system is paid for Eventually stop selling SRECs and claim all avoided CO2
Technical Scope 5.3 Megawatts, 8.4 Million KWH/year Avoid 3091 Metric Tons CO2 per year 9.4% of CO2 reduction goal Retire Solar Renewable Energy Credits (SRECs) and claim avoided CO2 from year 9 on. 27 Acres of Overgrown Fields & Lake Dredgings Connect to Existing Substation under lake and canal via underground cable
Solar Overview
Megawatts 20 Main Campus Power, Generated & Purchased During PV System Testing August 30, 2012 18 16 14 12 10 8 Charlton St Import MW Elm Drive Import MW CoGen Output MW West Windsor PV Output MW 6 4 2 0 12:00 AM 1:00 AM 2:00 AM 3:00 AM 4:00 AM 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00 PM 11:00 PM
Total Campus Imported Power, Megawatts PSEG Locational Marginal Price & Delivery, $/MWH Purchased Power and Power Price During Solar PV Testing August 30, 2012 20 100 18 90 16 Total Campus Import, MW PSEG LMP + Delivery, $/MWH 80 14 70 12 60 10 50 8 40 6 30 4 20 2 10 0 0 12:00 AM 2:00 AM 4:00 AM 6:00 AM 8:00 AM 10:00 AM 12:00 PM 2:00 PM 4:00 PM 6:00 PM 8:00 PM 10:00 PM 12:00 AM
Campus Microgrid
Simple Microgrid Concept KWH Local Generator Utility Meter Synchronizing Isolation Breaker Local Power Demands Central Utility Power Station KWH Utility Meter Isolation Breaker Local Power Demands
Microgrids Add Reliability KWH Local Generator Utility Meter Synchronizing Isolation Breaker KWH Local Generator Utility Meter Synchronizing Isolation Breaker Central Utility Power Station KWH Utility Meter Isolation Breaker KWH Local Generator Utility Meter Synchronizing Isolation Breaker
Microgrid Options GT, Diesel, Micro-turbine Economic Dispatch KWH Utility Meter Synchronizing Isolation Breaker Battery or flywheel reciprocating gas engine, solar PV, wind, micro-hydro Central Utility Power Station
Utility Company Power Feeds To Princeton Campus
Campus One-Line
A Few Princeton Campus Power Distribution Components
Emergency/Life Safety Generators
Campus Power During Hurricane Sandy
Must Do For Microgrid Reliability Distributed base-load generator(s) Ability to run isochronous Ability to isolate generator-load combinations Skilled, manual, in-person effort, not automatic Underground utility distribution Black start capability Gross load-shed capability
Should Do For Microgrid Reliability Fully commission complete systems Re-test periodically Test using realistic conditions Building-level load-shed capability Multiple fuel options Use emergency response teams periodically Plan for human needs
Less Than You d Expect In An Emergency 5 MW Solar PV Uncontrollable, volatile output Off at night and extreme weather Utility-interactive inverters can t run in isolation ½ MW Backpressure Steam Turbines Not significant scale Not controlled power output No black start Induction generators can t run in isolation 5 6 MW Emergency generators Serve emergency circuits only Usually carry much less than design load Most can t be synchronized
Water Use and Recovery
Princeton University Water Use 282 million GPY NJAW 91% Well 9% = 775 thousand gallons per day 34% is used in energy plant
Energy Plant Water Use 97 million gallons per year consumption 2011 Energy Plant Water Uses And Sources Largest users are cooling towers, then boilers, then NOx 2011 Energy Plant Water Uses By Month Strong summer peak; over 600k gpd.
Water Price Breakdown Average ~ 7%/year cost increase. Water and Sewer Prices by Year Supply = $3.36/kgal Discharge was $7.82/kgal New sewer rate of $10.24/ccf following Township-Borough merger in 2013, i.e., $13.90/1000 gallons
Initial Concept for Sanitary Water Recovery System Capacity Capacity: 400,000 gallons per day 146 million gallons annual Anticipated annual recovery 71 million gallons per year 95% of Energy Plant Water Supply 49% system utilization factor Arts Neighborhood rainwater recovery Primarily for storm water mitigation 1.2 million gallons per year Compatible with, not mutually exclusive of Sanitary Water Recovery
Existing & Proposed Concept 71 mgy recovered sanitary water for use in the energy plant Reduced water demand and sanitary discharge Water Flows 181 MGY Reduced water & sanitary expenses 110 MGY
Ongoing Opportunities Retro-commissioning, continuous commissioning Ground Source Heat Pumps Variable Frequency Drives Chilled Water Controls Optimization Real-time emissions calculation Energy Star & Smart Start grants as applicable Use Condensate to pre-heat Domestic Hot Water CHW-HTW Heat Pumps Biodiesel Deep Well Geothermal Fuel Cells Trash-to-energy
Thank you