Thermal Energy Storage (TES)on Campus:

Applications and Benefits

John S. Andrepont, PresidentThe Cool Solutions Company

Presented by James M. Schleife, Business Dev’t Mgr -

Big Ten & Friends – Mechanical and Energy ConferenceUniversity of Maryland-College Park – September 21, 2015

Acknowledgementsby John Andrepont

“I thank our host, John Vucci of UMCP, for the opportunity to present Thermal Energy Storage (TES) at this event.

“I wish my current medical situation allowed me to be with you today. And I thank Jim Schleife for standing-in for me.

“My health is improving well; and I plan to attend the IDEA Campus Energy Conference in Feb 2016 in Austin, TX, where I hope to see many of you in attendance.

“Chemotherapy does wonders, even changing appearances.”

frombefore . . . to after . . .

Terminology• CHP - Combined Heat & Power• CHW - Chilled Water• CHWS/R - CHW Supply/Return• CT - Combustion Turbine• DC, DE - District Cooling, District Energy• ES - Energy Storage• HW - Hot Water• LTF - Low Temperature Fluid• MCF - Mission Critical Facility• TES - Thermal Energy Storage• TIC - Turbine Inlet Cooling

Outline• Introduction and Background

– Thermal Energy Storage (TES) technologies– Extent of TES use on campus

• TES Benefits, with Actual Examples– Operating cost savings– Capital cost savings– Other benefits

• TES around the Big Ten• Conclusions and Recommendations

Introduction• Storage is a useful part of many, if not

most, man-made and natural systems:– Battery in your laptop computer– Ice-cube in your cold drink– Fuel tank in your car– Storage tanks in a municipal water system– Hot water tank in your home hot water system

Storage is also very useful for theelectric grid and its users; however, this poses technical and economic challenges.

Introduction• The value of storage has only grown as:

– air-conditioning drives demand growth and widens gaps between peak & baseload demand,

– time-of-day differentials grow in marginal heat rates, emissions, and value of electricity, and

– power gen from renewable energy grows, but often with a significant intermittent, or even out-of-phase, nature relative to demand (e.g. wind).

Thus, practical and economical energy storage is key in electric power systems - for the grid or for a campus micro-grid. Consider TES.

Cool, Latent Heat TES

• Ice TES– Water is frozen, off-peak (nights, weekends)– Ice is melted to serve cooling loads, on-peak– Conventional CHWS temps (40 to 44 ºF typ.)– Or can be Low Temp CHWS (34 to 39 ºF)– Relatively compact; typ’ly modular equip.– Needs Low Temp chiller oper’n (high kW/ton)

Latent Heat TES(typically Ice TES)

• Inherent Benefits, typically:– relatively compact storage volume– capability (of some Ice TES designs) for low

supply temps during discharge (34 to 44 ºF typ.)– std modular units in small to moderate sizes

• Inherent Drawbacks, typically:– low temps required for charging Ice TES– relatively little economy-of-scale

Cool, Sensible Heat TES

• Chilled Water (CHW) TES– An insulated tank with cooler denser CHWS

stratified below warmer less dense CHWR– TES acts as load off-peak, as chiller on-peak– Conventional CHWS temps (39 to 42 ºF typ.)

• Low Temperature Fluid (LTF) TES– Similar to CHW, but aqueous fluid <39 ºF– Lower supply temp (30 to 36 ºF typ.)– Larger Delta T; therefore, more ton-hrs / gal– LTF can also inhibit corrosion and microbio

Sensible Heat TES(typically CHW or Low Temp Fluid)

• Inherent Benefits, typically:– relatively simple & efficient - due to relatively

constant, warm (conventional) oper’g temps– dramatic economy-of-scale - low capital cost

per ton-hr or per ton, for large campus appl’ns• Inherent Drawbacks, typically:

– Large CHW TES vol. (but reduced by 33-50% with LTF TES, though still larger than Ice TES)

– Min. CHWS of 39 to 40 ºF with stratified CHW(but 30 to 36 ºF or lower, with LTF)

Inherent Characteristics of Cool TES(typical generalizations only) Ice CHW LTF

Volume good poor fairFootprint good fair goodModularity excell poor goodEconomy-of-Scale poor excell goodEnergy Efficiency fair excell goodLow Temp Capability good poor excellEase of Retrofit fair excell goodRapid Charge/Dischrg Capability fair good goodSimplicity and Reliability fair excell goodCan Site Remotely from Chillers poor excell excellDual-use as Fire Protection poor excell poor

2004 Survey of TES on Campus

159 examples of Cool TES on 124 univ campuses• Total = 1,808,408 Ton-hours

– 22% use Latent Heat TES (Ice)– 78% use Sensible Heat (CHW or LTF)

• Average size = 14,584 Ton-hrs per campus– Smallest = 320 Ton-hrs– Largest = 93,200 Ton-hrs

• Average TES load shift = 2,083 T and 1.6 MW

Many more campus TES added since 2004.

Repeat Owners of TES on Campus10 univ systems have 40 TES on 37 campuses:• U of TX has 7 CHW TES on 5 campuses.• U of CA has 8 CHW TES on 7 campuses.• Cal State U has 16 CHW TES on 14 campuses,

plus 1 Hot Water TES on one of those campuses.• Princeton U has 1 CHW TES and 1 LTF TES.

The old advertisement said:“Ask the man who owns one.”

Now, how about:“Ask the campus system that owns more than one.”

Operating Cost SavingsTES reduces peak power & shifts electric use,

lowering electric demand & time-of-use costs• TECO medical campus district - Houston, TX

– CHW TES (potential future conversion to LTF TES)– 64,300 ton-hrs– 8.8 million gals– 10 MW load shift2011 Real Time Pricing:– As low as -$0.10/kWh– As high as +$3.00/kWh– Saved up to $25,000/hr

Drivers for Net Capital Savings• Use TES in lieu of larger chiller plants:

– Without TES, chillers sized for design-day peakload (plus desired spare, if any)

– With TES, chillers sized for design-day averageload (plus desired spare, if any)

• Key times to capture capital savings:1. New construction2. Retrofit expansion of facility or growing loads3. Chiller plant modernization or rehabilitation

Large TES costs less than avoided chiller plant

Capital Cost SavingsMulti-million $ immediate net capital savings from TES:

1. Washington State U - Pullman2. Climaespaco district energy (Lisbon, Portugal)3. Chrysler R&D campus (MI)4. DFW Int’l Airport (TX)5. OUCooling - convention & industrial district cooling (FL)6. U of Alberta - Edmonton (Canada)

• CHW TES• 7.9 million gals• 60,000 ton-hrs• 7,215 ton shift• 5.4 MW elec shift

Examples of TES SavingsTES Operating Capital

Proj. TES Capacity Savings SavingsType Type (Ton-hrs) (Million $/yr) (Million $)retro CHW 17,750 $0.26/yr $1 to 2new CHW 39,800 $1.16/yr $2.5retro CHW 60,000* $0.60/yr $4new CHW 68,000 >$1.0/yr $3.6retro LTF 90,000 ~$2/yr $6retro CHW 160,000* >$0.5/yr >$5

* pre-designed to expand (50-70%) from CHW to LTF

Improving the Economics of CHP• TES flattens cooling & electric hourly load profiles:

– Peak elec demand reduces; base load demand rises.– Justifies larger CHP w/ lower unit Cap$ for better econ’s.

• Examples include small to large CHP with TES:– McCormick Place - Chicago (3 MW of CHP)– Princeton U (15 MW)– Reedy Creek (Disney World campus) - FL (32 MW)– U of Texas at Austin (over 100 MW)

• 2 CHW TES (10 Mgals total)• 69,000 ton-hrs• 20,000 ton (~12 MW) load shift

Fire Protection• CHW TES doubles as fire protection.

– Abbott Labs (IL); ARCO (TX); Chrysler (MI)– GM (OK, MI); Phoenix News (AZ); Shell (TX)– Pratt & Whitney (CT); State Farm (GA, IL)– 3M Corporation

R&D campus (MN)• CHW TES• 32,000 ton-hrs• 4.1 million gals• 5 MW load shift

Mitigating Piping Bottlenecks (1 of 2)• TES can be at a remote satellite location.

– U of Alberta-Edmonton; U of Nebraska-Lincoln– Washington State U-Pullman– U of Illinois - Urbana-Champaign

• CHW TES (LTF)• 50,000 ton-hrs• 6.5 million gals• 7 MW load shift

Mitigating Piping Bottlenecks (2 of 2)• Lower supply temps expand CHW Delta T:

– Princeton U (NJ)• LTF TES (32 F)• 40,000 ton-hrs• 2.7 million gals• 7 MW load shift

– DFW Int’l AP (TX) • LTF TES (36 F)• 90,000 ton-hrs• 6.0 million gals• 20 MW load shift

Seasonal Free Cooling• The use of “free cooling” via cooling tower

operation in cool weather can be expanded with TES to more hours per year.– Abbott Labs

pharmaceutical manufacturing facility (IL)• CHW TES• 10,000 ton-hrs• 1.3 million gals• 2 MW load shift• increases free cooling operation in spring and fall

Deep Water Source Cooling• TES can supplement and improve the

operation and economics of “deep water source cooling” from lakes or seawater.– Cornell Univ.

campus (NY)• CHW TES• 38,000 ton-hrs• 4.3 million gals• 7 MW load shift• supplements a 20,000 ton deep lake cooling system

Reduced On-Site Energy Use• TES inefficiencies: 1) heat gain, 2) pumping.• TES efficiencies: 1) cool nighttime condensing,

2) avoided low-load oper or chillers & auxiliaries.• Examples of net energy savings from TES:

– State Farm (IL)• 89,600 ton-hrs CHW TES• annual kWh/ton-hr reduced 3% (modeling)

– Texas Instruments (TX)• 24,500 ton-hrs CHW TES• annual kWh/ton-hr reduced 12% (measured)

Reduced “Source” Fuel & Emissions• Power plants “on the margin”

– Off-peak (nights): efficient, low-emission, base-load units (e.g. CT combined cycle)

– On-peak (days): inefficient, high-emission, peaking units (e.g. simple cycle CT or oil-fired steam unit)

• Independent studies in CA, FL, TX, and WI showed shifting peak generation to off-peak:– Reduced fuel use (Btu/kWh) and emissions of

SOX, NOX, particulates, and CO2 (lbs/kWh):• typically by 15 to 20%, sometimes 30 to 50%.

With Wind / Solar, TES can save even more!

Integration of Renewable Power• Renewable Portfolio Stds => Wind & Solar

– intermittent; even out-of-phase with demand– Coal+Nuke+Wind can exceed night demand– Nighttime power trades negative at times, e.g.

• As low as negative $0.10/kWh in TX in 2011• As low as negative $0.20/kWh in NE in 2012

• Energy Storage is a key growing need, e.g.– Batteries, Pumped Hydro, Compressed Air, Flywheels

But large CHW TES excels over all those in:cap$, efficiency, siting/permitting, schedule, lifetime, maturity

Wind Power ~20% during Peak Dmnd

Source: ERCOT, www.ercot.com

kWh Value Varies: +$2.50 to -$0.10while grid demand varies: 100-50%

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Turbine Inlet Cooling (TIC)• TIC w/ TES for max hot weather CT output.

– Princeton U; Reedy Creek (Disney World);– Calpine; Climaespaco; Chicago MPEA; TECO– Dominion Energy (4 in PA & VA; 59 MW TES)– Saudi Electricity Co.

• CHW TES• 193,000 ton-hrs• 7.9 million gals• 48 MW load shift• 180 MW extra power• Under $300/kW

Emergency Cooling for MCFs• Back-up at Mission Critical Fac’s (data ctrs)

– Princeton U; Apple; Bank of Amer.; Citibank– Covidien; DuPont Fabros; eBay; Equinix; HSBC– MCI; Nationwide; Target; US Bank; many others– Capital One

data center (VA)• CHW TES• 900 ton-hrs• 180,000 gals• 1,500 tons x 36 mins

TES around the Big Ten• Ice TES – Maryland (serves only a fraction of campus)

• CHW TES– Illinois (50,000 ton-hrs)– Iowa (7,000 ton-hrs)– Maryland’s Baltimore County campus (10,500 ton-hrs)– Michigan (17,000 ton-hrs)– Nebraska (16,326 ton-hrs + 48,929 ton-hrs planned)– Penn State’s Med campus (12,500 ton-hrs)

• Studies have shown operating and capital savings by adding CHW TES (in lieu of more chillers) at– Mich’s North campus, Nebraska’s Med campus, Purdue.

U. Of Nebraska-Lincoln East (2012)2009: 7,000 T installed chillers; 4,000 T “firm” (N-1).Peak load growing: 5,020 T (2012) to 6,000 T (2015).2012: postponed new chiller, but added CHW TES:

16,326 ton-hrs @ 42/52 °F2.9 Mgals (100 ft D x 50 ft H)Shifts 2,000 T (1.6 MW), withpotential for 4,000 T (3.2 MW).Near 0-yr simple payback andover $4 M in 20-yr NPV.

A much larger CHW TES is nowplanned for UNL’s City Campus.

Summary• Energy Storage adds value to elec grid & microgrid.• 150+ TES already on campus; many repeat users.• TES (Ice, CHW, or LTF TES) offers low cost ES.• TES reduces peak demand, lowers operating $.• Large CHW TES often saves capital $ vs. chillers.• Many potential secondary benefits of TES:

– flatter load profile, improved economics of CHP,– improved energy efficiency on-site & at source,– dual-use fire protection, de-bottleneck piping,

turbine inlet cooling, MCF back-up cooling, etc.

Conclusions1. Whenever planning capital investments for

campus cooling, always explore TES options.

2. Whenever considering Energy Storage, always evaluate TES options (not just electric batteries).

3. And consider Hot Water TES for HW District Heat.

TES can reduce both operating and capital costs,and improve efficiency, redundancy, and resiliency.

Questions / Discussion ?Or for a copy of this presentation, contact:

John S. AndrepontThe Cool Solutions CompanyCoolSolutionsCo@aol.comTel: 630-353-9690

James M. Schleife

JSchleife@CBI.comTel: 815-439-4015