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Thermal Energy Storage and Peak Load Reduction. Mark M. MacCracken, PE, LEED AP , Pte CALMAC Mfg. Corp. Fair Lawn, NJ Calmac.com. NARUC Summer Meeting 7-16-07. Benefits of Thermal Energy Storage. Reduces Peak Demand at most critical time 20-40%
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Thermal Energy Storage and Peak Load Reduction Mark M. MacCracken, PE, LEEDAP, Pte CALMAC Mfg. Corp. Fair Lawn, NJ Calmac.com NARUC Summer Meeting 7-16-07
Benefits of Thermal Energy Storage • Reduces Peak Demand at most critical time 20-40% • Reduces consumer’s energy costs 10-20% • May reduce energy usage at the building up to 14% • Reduces source energy usage at power plant 8-34% • Reduces emissions up to 50% • Increases Load Factor of Generation up to 25% • Provides operational flexibility
Thermal Energy Storage For Off-Peak Cooling • What is it? • How does it work? • Why is it Green? • Other “Green” Advantages • Applications/Case Studies
Most common TES System Water Heater (Electric) Assume one low-flow shower ((2.5gpm x 8.33 lb/gal x (110-60)) x 60 minutes/hr / 3,414 Btu/kW = 18.3 kW East Coast of US 100,000,000 people x 25% x 1/12 Hr/shower x 18.3 kW= 38 Gigawatts = CA Electric Peak on Summer day 4.5 kW Heater • Gas Water Heater • Design Load = 2 Showers at a time • 18.3 kW x 2 x 3414 = 124,950 Btus TES has already impacted US infrastructure
Utility Load Factors* in the USA *Load Factor = Avg. Load Peak Load
Peak Load 2000 kW Avg. Load 1050 kW ASHRAE 90.1 Base BuildingNon-Storage Electrical Profile 6 am Noon 6 pm Total kWh = 28,000/day (Load Factor = 53%)
Peak Load 1500 kW Avg. Load 800 kW Design 30% better than 90.1 Non-Storage Electrical Profile 6 am Noon 6 pm (Load Factor = 53%) Total kWh = 19,200/day
600 kW Shed Peak Load 900kW Charging Storage Off Peak Cooling (OPC) Electrical Profile 40% Peak Load Reduction Avg. Load 800kW 6 am Noon 6 pm (Load Factor = 88%) Total kWh = 19,200/day
Power continue to be less expensive at Night because of Generation Load Factor 4 Buildings x 1 Megawatt = 4 Megawatts 8,000 mW-h Sold 5 Buildings with TES @ 0.8 mW = 4 Megawatts 10,000 mW-h Sold! The same generator produces 25% more sellable kW-h!
3-D Electric Load Profile -- Full Year 4200 ton-hr of Storage Installed 1990
Large Scale Sustainable Energy Future will Require Storage 1 TRILLION Watts of Generation in USA (approx.) Costs of New Generation, Installed Combined Cycle Gas Turbine ~ $0.50 to $1.00/Watt Nuclear $3.00 to $6.00/Watt New Coal Plant $1.50/Watt New Clean Coal $2.00/Watt Wind (30% Cap Factor ~ 0 Peak Reduction) $1.60/Watt PV (30% Cap Factor ~ 15% Peak Reduction*) $7.50/ Watt STORAGE (Thermal) $0.50 to $1.00/Watt *NREL Report
Thermal Energy Storage For Off-Peak Cooling • What is it? • How does it work? • Two Basic Systems • Water • Ice
Conventional HVAC Chilled Water System 40 56 Chiller Load 40
Water Storage System 40 56 Chiller Warm Water 56 F Load Thermocline Cold Water 40 F 40
Ice Storage Systems Control Logic • Chiller Based System • Closed System Heat Transfer Fluid 75%H20/25%EG So what is “Different”? Temperature Modulating Valve Storage Tanks
Bank of America Tower at 1 Bryant Park, New York CityBank of America / Durst Organization History Channel “Sky Scrapers” 9-7-04 ~2.2 Million ft2Going for LEED Platinum
Thermal Storage Tank Ice-on-Coil Internal Melt Expansion Chamber Tank Insulation Heat Exchanger
Ice Ice Making (Off-Peak) 500 ton Chiller Coil & Glycol 25 31 1000 ton On-Peak Load 25 31 Temperature Control Valve
Direct Cooling 500 ton Chiller Coil & Glycol 44 54 500 ton Load Ice 44 Temperature Control Valve
Melted Ice Ice and Chiller Cooling 500 ton Chiller Coil & Glycol 52 60 1000 ton Load Ice 34- 44 44 44 Temperature Control Valve
Load Reduction 90 ton or ~ 90 kW Basic Operating Modes for any Storage System Storage System 60 ton Chiller 1,100 ton-hr Storage ICE DISCHARGE ICE CHARGE CHILLERS
Would need 25% of roof space on 100 story building! Space? • Full Storage: 0.70% of cooled floor space • Partial Storage: Ice provides about 33% of a cooling system reducing ice tank floor space to 0.23% of cooled floor space. 1 ton cools 500 ft2 1 tank provides 20 tons 1 tank cools 10,000 ft2 1 tank needs 70 ft2 (60 ft2 ) Same ratio as the water heater in your house
Ice Storage Tanks for the entire Project National Air and Space Museum, Washington, DC USA 4,700 Ton Hrs of StorageOn-Peak Chiller – 1122 TonsOn-Peak Ice Contribution – 729 Tons40% On-Peak Chiller Demand Avoided
Thermal Energy Storage Myths Article (Ashrae Journal Sept 03) • 1. Uncommon • 2. Too Much Space • 3. Too Complicated • 4. Doesn’t Save Energy • 5. Too Expensive • 6. Lack of Redundancy (Risky) • Rates Will Change • Modeling doesn’t Show Results Reality: TES is a Proven Technology that saves Money and Energy
Thermal Energy Storage For Off-Peak Cooling • What is it? • How does it work? • Why is it Green?
LEEDTM Credits Materials & Resources Water Efficiency Indoor Environmental Quality Sustainable Sites Energy & Atmosphere • Sustainable Sites: 14 points • Water Efficiency: 5 points • Energy* & Atmosphere: 17 points • Materials & Resources: 13 points • Indoor Environment Quality: 15 points • Innovation & Design: 5 points 69 points *10 Energy Credit are based on ASHRAE 90.1 which is based on Energy COST Reduction
Real reasons Off-Peak Cooling is Green: • It is much more Energy Efficient to create and deliver a kWh of Electricity at night than during the hot of the day. • Research from the California Energy Commission on 2 Cal. Utilities Reports 8 to 34% savings in raw fuel when comparing On and Off Peak Operation! • Heat Rates for Base Load Plants ~7,800 Btu/kWh vs. Peaking Plants ~9,400 to 14,000 Btu/kWh • The last power plants to come on during peak hours are normally the dirtiest per kW • Ashok Gupta (Director of Energy, NRDC) in NYTimes article “Peak Shifting results in lower emissions because some of the plants used to meet demand peaks are among the dirtiest in the city” • New CA Report by Greg Kats The Costs and Financial Benefits of Green Buildings states Peak power in CA is twice as dirty as Off Peak Power.
Thermal Energy Storage For Off-Peak Cooling • What is it? • How does it work? • Why is it Green? • Other “Green” Advantages
Other “Green” Issues • Safety Factors/Redundancy (Oversizing) • Well documented that oversizing chiller plants creates less efficient real world operation. • Engineers have to protect their license • Storage is the Natural solution
Safety Factor and Redundancy Without Oversizing for same Cost Storage System 2 - 400 ton Chiller 3,500 ton-hr Storage * as per GSA Guideline P-100
Design Day Off-Peak Cooling System Storage System 2- 400 ton Chillers 3,500 ton-hr Storage Installed Chillers Max Capacity 500 ton Load Reduction or ~ 375 kW STORAGE DISCHARGE CHILLERS (ONLY 500 TONS) STORAGE CHARGE
Costs of Storage • What’s the Installed Cost of a ton of Chiller Plant? • $1000/ton , $1200/ton, $1400/ton $1600/ton, $1800/ton • Storage Costs installed ~ $100 to $150 per ton-hr • Depending on location, application and design • For each 1 ton of chiller you reduce you need about 8 to 9 ton-hrs of storage. Costs are similar to conventional design for New Construction
Thermal Energy Storage For Off-Peak Cooling • What is it? • How does it work? • Why is it Green? • Other “Green” Advantages • Applications/Case Studies
Durst Headquarters Retrofit 1155 Avenue of the Americas 41 Stories3400 Ton Hours StorageAvoids 700kW out of 3500kW Original Total
Ice Plant in Series with Water Chiller TO LOAD FROM LOAD 490 ICE-MAKING TONS HX DEMAND LIMITED TO 700 TONS ICE STORAGE ICE STORAGE TS VFD PUMP ~1200 TONS
Credit Suisse11 Madison Ave. 30 Stories, 2.2 Million Ft2 6200 Ton Hours Storage Avoids ~ 900 kW NYSERDA Incentive $620,000 Main reason for Storage: Resiliency
Bank of America Tower ICEBANK Facts Over Half a Million Pounds of Ice made every night. Enough Ice to Cool 250 Homes 1000 Tons of Air Conditioning Shifted to Off-Peak
Goldman-SachsNew York City 2.2 Million Sqft.6,000 tons Peak4,500 tons of Chiller (Only 3000 during the Day)19,000 Ton-hr of Ice Storage~2 MW ReductionGoing for LEED Gold
Off-Peak Cooling… in over 6000 installations in 35 countries, many installed over 20 years ago
Questions? Mark M. MacCracken, CEO MM@Calmac.com www.Calmac.com 201-797-1511 NARUC Summer Meeting 7-16-07