Princeton University Microgrid
IDEA evolvingENERGY Conference
Toronto, Canada
28th – 30th October 2014
Edward “Ted” Borer, PE
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
Energy Demands at Princeton
> 180 Buildings Academic Research Administrative Residential AthleticEnergy 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 40,000 Ton-hours
Plant Energy Balance
Campus Energy Users Chilled Water & Thermal Storage Systems Gas Turbine & HRSG Duct Burner & HRSG Auxiliary Boilers PSEG Electricity Natural Gas #2 Diesel Fuel Oil Electricity Steam Chilled Water Biodiesel Fuel Oil Backpressure Turbines Solar PV Electricity
Chiller Cooling Tower Hot Cool Warm vapor Thermal Storage Tank
Cold water To HTX or tank ~ 32° F
Warm water from HTX or tank ~ 56° F
Plate & Frame Heat Exchanger Warm water from Campus ~ 58° F Cold water To Campus ~ 34° F
Princeton Chilled Water Use
Campus Chilled Water Production, June 2002
0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 20,000 22,000
10-Jun 11-Jun 12-Jun 13-Jun
T o ta l C h il le d W a te r F lo w 0 10 20 30 40 50 60 70 80 90 100 110 O u td o o r T e m p e ra tu re Total Flow, gpm Outdoor Temp
Princeton Summer Steam Use
0 20 40 60 80 100 120 140 16022-Jun 23-Jun 24-Jun 25-Jun 26-Jun 27-Jun
Steam Flow, M#/hr
Gas Turbine Power Turbine Gearbox Electric Generator
Hot exhaust Gas CO Catalyst AC Electricity Steam Air Feed Water Heat Recovery Boiler Exhaust Gas Fuel & Water
How Much More Efficient is
Combined Heat & Power?
Princeton Power Demand
With Cogen Dispatch To Minimize Cost
-2 0 2 4 6 8 10 12 14 16 18 20
08 Jul 05 08 Jul 05 09 Jul 05 09 Jul 05 10 Jul 05 10 Jul 05 11 Jul 05
Me g a w a tts . Generation Campus Demand Power Purchase
Princeton Economic Dispatch System
ICETEC
PJM Electric Price NYMEX gas, diesel, biodiesel prices Current Campus Loads Weather Prediction Production Equipment Efficiency & Availability “Business Rules” Historical Data Generate/Buy/Mix
Preferred Chiller & Boiler Selections
Preferred Fuel Selections
ICAP & Transmission
Warnings Operating Display Historical Trends Live feedback to Icetec Operator Action Biodiesel REC value
& CO2 value
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
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.
Data Center Absorption Chiller
600 tons of cooling using
only “waste” exhaust heat
from a 1.9 megawatt
gas-fired 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.
Reduced Chilled Water Use
1 2 3 4 5 6 7 8 9 10 0 5 10 15 20 25 30 35 40 Camp u s F loo r A rea ( S q .Ft .) Mi lli on s A n n u al Ch ille d W ater Use (T o n -Ho u rs) Mi lli on s YearPrinceton University Chilled Water Load Growth
Chilled Water Bldg Sq.Ft.
Reduced Annual Steam Energy
1 2 3 4 5 6 7 8 9 10 0 100 200 300 400 500 600 700 800 900 1,000 Camp u s F loo r A rea ( sq.f t.) Mi lli on s A n n u al S tea m Use (lbs) Mi lli on s Fiscal YearPrinceton University Annual Steam Use
Steam Use Floor Area
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
Technical Scope
5.3 Megawatts, 8.4 Million KWH/year
Avoid 3091 Metric Tons CO
2per year
9.4% of CO
2reduction goal
Retire Solar Renewable Energy Credits (SRECs) and claim
avoided CO
2from year 9 on.
27 Acres of Overgrown Fields & Lake Dredgings
Connect to Existing Substation under lake and canal via
0 2 4 6 8 10 12 14 16 18 20 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 M e gawat ts
Main Campus Power, Generated & Purchased During PV System Testing August 30, 2012
Charlton St Import MW Elm Drive Import MW CoGen Output MW
0 10 20 30 40 50 60 70 80 90 100 0 2 4 6 8 10 12 14 16 18 20 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 PS EG Loc ation al M ar gi n al Pr ic e & D e liv e ry , $/M WH To tal Cam p u s Im p o rte d Pow e r, M e gawat ts
Purchased Power and Power Price During Solar PV Testing August 30, 2012
Total Campus Import, MW
Simple Microgrid Concept
Central Utility Power Station KWH Utility Meter Synchronizing Isolation Breaker Local Generator Local Power Demands KWH Utility Meter Isolation Breaker Local Power DemandsMicrogrids Add Reliability
Central Utility Power Station KWH Utility Meter Synchronizing Isolation Breaker Local Generator KWH Utility Meter Isolation Breaker KWH Utility Meter Local Generator KWH Utility Meter Synchronizing Isolation Breaker Local Generator Synchronizing Isolation BreakerMicrogrid Options
Central Utility Power Station KWH Utility Meter GT, Diesel, Micro-turbinereciprocating gas engine, solar PV, wind, micro-hydro…
Battery or flywheel Economic Dispatch Synchronizing Isolation Breaker
Utility Company Power
Feeds To Princeton Campus
A Few Princeton Campus
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
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
Princeton University Water Use
• 282 million GPY
– NJAW 91%
– Well 9%
• = 775 thousand
gallons per day
• 34% is used in
Energy Plant Water Use
• 97 million gallons per
year consumption
• Largest users are
cooling towers, then
boilers, then NOx
• Strong summer peak;
over 600k gpd.
2011 Energy Plant Water Uses And Sources
Water Price Breakdown
• Average ~ 7%/year cost
increase.
• 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
Water Flows
• 71 mgy recovered
sanitary water for
use in the energy
plant
• Reduced water
demand and
sanitary discharge
• Reduced water &
sanitary expenses
181 MGY
110 MGY
