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Energy Storage in Chicago Lowering Peaks to Reduce Utility Bills
1
Evan Berger Director of Energy Solutions, North America
Calmac Corp. [email protected]
November 2017
Utility Bill Basics 1. There are three ways to lower electric costs:
a) Buy fewer units of energy.
b) Purchase it when it’s cheaper, at night.
c) Negotiate a better rate with your 3rd party supplier.
Utility Bill Basics 2. Commercial Rates are Different than
Residential Rates:
a) Residential Rates are based solely on usage (kWh)
b) Commercial Rates are based on a mixture of usage (kWh) and Demand (peak kW).
Utility Bill Basics 3. Rates and tariffs are complicated. Why? A few possible* reasons come to mind—
a) Lawyers write them
b) Regulators dislike plain English
c) The less customers know about their electricity bills, the more utilities and Third-Party Suppliers can possibly* earn more money at their expense
*Note: pure speculation
Demand Charges
Types of Demand Charges: 1. Utility Demand Charges 2. Grid Demand Charges (from PJM,
NYISO, etc.)
Definition: any electricity charge that is assessed on a per-kW basis
Note:moreo)enthannot,GridDemandChargesare“blended”inThirdPartySupplierbillsandthusnotvisibletothecustomer;we’lldiscussthisissueatgreatlengthlaterinthepresentaDon
Let’s Look at John’s ComEd Bill—
Nonresidential Sample Hourly Supply Bill
Nonresidential Sample Hourly Supply Bill
Altogether, Demand makes up 44.6% of the pre-tax bill
Note: view in slideshow mode
Utility Demand Most buildings have a “bell shaped” load curve
• U"litydemandisbasedoffthepeakinterval(30mins)inagivenbillingmonth• Alwaysoccursontheho?estweekdaya@ernoons–coolingsetsthepeak
MondayTuesdayWednesdayThursdayFriday88◦89◦86◦92◦86◦
0 kW
200 kW
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Traditional Cooling
Typical Office Building
Calculating GRID Demand IntroducingtheGrid–PJMInterconnec3on
• PJM is the world’s largest grid, covering 13 states from the Mid-Atlantic all the way down to North Carolina and over to Illinois
• PJM schedules the reliable flow of power from generators to consumers – and charges customers for the service
PJMCapacityChargesarebasedonacustomer’sPeakLoadContribu"on(PLC);itiscalculatedbasedonthecustomer’sconsump"onduringthefivehighesthoursoftotalGriddemand(kW)duringthepreviousyear.Theseareknownasthe5CPs–thefiveCoincidentPeakHours
Calculating GRID Demand
The5CPshavealwaysoccurredduringSummera?ernoonsCalculating GRID Demand
5CP Chart, 2010-2016
2016 2015 2014 2013 2012 2011 2010
July 25, 3-4pm
July 20, 4-5pm
June 17, 5-6pm
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June 8, 4-5pm
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July 27, 4-5pm
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July 1, 5-6pm
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July 22, 2-3pm
Aug 11, 4-5pm
PJMDemandChargesareRatchetedRatcheted:OnceyousettheDemandkW,itstaysatthatlevelonyourbillforafullyear.Note: Some utility Demand Charges are also ratcheted
Calculating GRID Demand
Comparison: Traditional Cooling vs. Load Shifting
• Compared to a 350 ton chiller, Thermal Storage plus a 190 ton chiller yields $15,000 in annual savings
• Much of the savings comes from the winter months, when they benefit from reduced PJM ratchet costs
Results derived by Trace700
The Demand Charge Effect ComEd Very Large Load Delivery Class, Secondary Energy (usage):
Day: $0.045/kWh Night: $0.045/kWh
Demand: $11.70/kW/Month
How big an effect is the Demand Charge??
Energy is 61% less expensive at night
$0.045/kWh
$0.116/kWh
Demand Charge Effect….. Do the Math (Back of the Envelope) Conventional Chiller System Demand Cost /month
1000 tons x 0.8 kW/ton = 800kW 800 kW x $11.70 = $9,360/month
Energy Usage for Chiller for Month
1000 tons x 10 Hrs x 75% x 0.8 kW/ton x 22 days/month = 132,000 kWh
Approximate Cost for Demand / kWh
$9,360/132,000 kWh/month = $0.071/kWh
Therefore Daytime Energy = 4.5 cents + 7.1 cents = 11.6 cents/kWh
Base Load
LightingFans
Pumps
[CATEGORY
NAME]Chiller
0200400600800
100012001400160018002000
Peak Load 1500 kW
The Role of Energy Storage Most typical buildings have a “bell shaped” load curve
kW
0
200
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600
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Base Load
LightingFans
Pumps
[CATEGORY
NAME]Ice Cooling
Ice
Peak Load 1200 kW
Chiller
The Role of Energy Storage Storage flattens out the peak and reduces demand charges
Ice-Making
kW
Across the U.S., ice storage is all about reducing demand chargesIn Chicago, shaving 300kW would save over $30,000 per year.
When Would you Fill-up?
Daytime
$ 2.50/gallon
Nighttime
$ 0.99/gallon
