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On-Site Strategies for Power Delivery

Reliability- Applications

UC Irvine

Advanced Power and

Energy Program

Presented at the

SoCal Chapter of AEE Annual Conference 2011 Energy Security: Keeping the Power On

September 22, 2011

Presented by

Richard Hack - PE, CEM

University of California, Irvine

© Advanced Power and Energy Program, 2011 2/29

Outline

• Energy Storage/carry-through

• On-Site Power Generation/CHP

• Example

• Concentration on “on-site” and end-use customer level systems (as opposed to grid scale).


Energy Storage

For short term outages, electric energy storage may suffice:

• Ultra-Capacitors: sags/surges • Flywheels:


Energy Storage

• With possible exception of hydrogen/fuel cell energy conversion, all have a finite duration

• Power delivery (kw) and energy capacity (kw-hr) both drive costs.

• Energy storage isn’t limited to power interruptions. • Great potential for demand response curtailment benefit

• Utilities can be/are supportive of large scale storage in system for demand reduction in critical periods.

• Financial rewards(?)

• Sandia Report1: • Characterizes 26 benefits of energy storage in

catagories of: 1) Electric Supply, 2) Ancillary Services,

3) Grid System, 4) End User/Utility Customer,

5) Renewables Integration, and 6) Incidental.

1: Energy Storage for the Electricity Grid:Benefits and Market Potential Assessment Guide: SAND2010-0815 Feb 2010


On-Site Power Generation

• Not diesel gen set back-up systems • On site power generation, grid parallel but capable

of switching to “islanding” mode in event of power

interruption.

• Can be combustion systems (reciprocating engines, gas turbines, boiler/steam turbine)

• Can be electrochemical based systems (fuel cells) • Can be of configured for high overall efficiency

operation through both generation of electricity

and capture of waste heat for use.

• In case of grid reliability, need waste stream to be available to support critical needs.


What is DG / C-CHP?

• Generation of electric power at or near the point of final use with some form of prime mover and the capture of waste heat to provide some additional beneficial use.

DG: Distributed Generation ( < 20 MW)

C-CHP: Combined Cooling, Heat and Power

• Opportunity to “get more bang for your buck” by getting two or maybe three uses for each unit of energy purchased and consumed on site.


Why DG / C-CHP?

• Why would I want to generate my own electricity? • Power Reliability

– Power Quality – Back-up Power

• Save $$$$ – Increased Efficiency of overall system

• Added capacity deferring system feed upgrade costs • Greenhouse Gas Emissions

– Environmental Stewardship – Value of Carbon Credits.


Opportunity for Heat Recovery

Thermodynamic Limitation

• Cannot transform energy at 100% efficiency.

Efficiency = η = (useful energy out) / (energy in)

• Generation of electricity from fossil energy resources will result in wasted energy.

– Efficiencies range from


Opportunity for Heat Recovery

Carbon In / Work = 154”C” / 75 Carbon In / Work = 100”C” / 75

Net Carbon Reduction: 35%


Reliable and Premium Power

Cost of Power Outages are exorbitant: EPRI/LBNL estimate from 2006: $79B annually (in 2002 dollars)1

• Commercial: $56.8B (72%) • Industrial: $20.4B (26%)

Individual Sectors2 (2000 $):

• Cellular Communications: $41K/hr • Credit Card: $2.6M/hr • Securities/Brokerage: $6.5 M/hr

DG can provide support

• Applications that require greater reliability than the grid alone. • In conjunction with the grid, “eight-9’s” or better reliability possible

• 0.31 sec / year

1: Cost of Power Interruptions to Electricity Customers in the United States: LBNL-58164; Feb 2006

2:Electric Power Interruption Cost Estimates for Individual Industries, Sectors, and US Economy: PNNL-13797; Feb 2002


Reliable and Premium Power

Premium Power:

• Could be considered the same as “reliable” power • IT-Grade Power • Applications where power quality is questionable

• Harmonics • Voltage sags/surges • End of line applications that require greater reliability

than the grid alone.

• Issues likely to get worse with increase renewables

• Computer intensive facilities likely most sensitive. • Some critical industries (semi-conductor/chips)


Energy Saving Opportunities

DG / C-CHP provides a means for locally generating

electric power and other beneficial products:

• Hot water/Steam • HVAC “Cooling” via absorption / adsorption

chillers

Plus:

• Opportunity to generate with grid outage • Store thermal energy for crucial heating/cooling

need


Waste Heat Recovery

• Recall that there is approximately 70-80% of the heat energy input to prime mover (in the form fuel input)

becomes wasted typically as heat:

• In the exhaust • Cooling water/oil system • Radiation to the atmosphere.

• Can not capture all of the heat in the exhaust; • Do not want to reduce exhaust temp too much • Exhaust condensation-corrosion issues • Exhaust dispersion – lofting

• Amount of waste heat available varies by prime mover. • For MTG, reasonable ROT is 50 - 60% of the exhaust heat can be

captured.

• e.g. Capstone C65; 400,000 btu/hr of heat; 550 F


Hot Water / Steam

• Hot Water • Amount of heat recovery and temperatures varies

depending upon inlet temperatures and flow rates

Figure courtesy Ingersoll-Rand

• Steam: • Nominal 15 psig steam possible with separate heat

recovery steam generator

• Higher pressure steam possible with auxiliary duct burners to increase exhaust energy/temperature


Desiccant Dehumidification

• Desiccant Dehumidification can provide substantial reductions in energy consumption:

• Reduced space conditioning loads – eliminates latent heat cooling requirements

• Desiccant dehumidifiers are most energy efficient methodology for moisture removal (ASHRAE 90.1 2004)

– For DG/CHP, regen-energy is “waste” energy – Discharge air @ approx 15% RH.

• Desiccant dehumidifiers located upstream of HVAC systems to dry air prior to cooling.

• Conventional refrigeration. • 80 F, 80 RH ambient make-up; 70 F, 40% RH supply air

– Enthalpy change:~15 btu/lb dry air cooling – @ 200 scfm, ~2 – 2.5 tons of cooling

•


Absorption Chilling for Cooling Needs

Heat Activated Cooling.

• Significantly reduced electric energy needs (pumping loads)

• Simplified Operating Principles • Refrigerant material (water for Li-Br, ammonia in other) is part of a

liquid binary mixture

• Easier/more efficient (less energy) to pump liquid to higher pressures than gas.

• Refrigerant/carrier pumped to “high” pressure • Heat (from prime mover) boils off high pressure refrigerant • “Expand” refrigerant to lower pressure = cooling • Refrigerant is reabsorbed, with captured heat • Liquid binary mixture is cooled via cooling tower

– Requires cooling towers with capacity of approx 2x the heat removed.

• Process repeats



• Not as energy efficient as electric chillers in producing “cold” but does it with energy that

would otherwise not be utilized (exhaust waste

heat)

• In critical situations, does not compete for electric energy from generation system

Electric Chillers:

COP* 3 – 6 (EER = 10.5 – 21)

Absorption Chillers:

COP = 0.7 Single effect (EER = 2.5)

COP = 1.3 Double effect (EER = 4.5)

*COP = coefficient of performance = energy out/energy in



Single Effect Chillers:

• Lower inlet temperatures: • 180 F water to approx 210 F (no need to consider steam

system headaches)

Double Effect Chillers:

• Higher inlet temperatures: • 250 F to 350 F hot water/steam • Direct firing from exhaust from prime mover.

Lithium Bromide – Water

• Temperatures limited to approx 40 F • HVAC • Medium Temp Cooling


Adsorption Chilling for Cooling Needs

Different principle than absorption chillers.

• Uses a benign adsorbent media (silica gel). • No safety hazard • Cooling occurs as a result of evaporation of

coolant from media.

Look to Power Partners (vendor, Table 7)


Data Center Cooling Needs

Air Temperature:

• ASHRAE standard: – 68F – 77 F, 40% - 55% RH

• ASHRAE Technical Committee TC9 2008 recommendation:

– 64.4F – 80.6F, 60% RH, Dew Point 41.9F – 59F

Chilled Water Temperature: – 50 – 55F discharge temp – 65 – 70 F return temps

• Very amenable to thermally activated chilling


Case Study Opportunity - Commercial Office

Multi-Tower Commercial Office Building

•1.11 million sq-ft

•Central Plant

•TES

Commercial Office Building Complex(average day, Aug 1 - Sept 30)

0

100

200

300

400

500

600

700

0:00 6:00 12:00 18:00 0:00

En

erg

y:

15

min

in

terv

al

2 MW demand

Total Electric

[kw-hr]

Chilling

[RT-hr]

Modified Electric / Heat Ratio(average day, Aug 1 - Sept 30)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0:00 6:00 12:00 18:00 0:00

Chilling Provided by double effect

absorption chillers: COP = 1.3


Typical Data - Commercial Office

Commercial Office Building Complex(average day, Aug 1 - Sept 30)

0

100

200

300

400

500

600

700

0:00 6:00 12:00 18:00 0:00

En

erg

y:

15

min

in

terv

al

2 MW demand

As Measured

Electric Energy [kw-hr]

Peak Demand: 2.53 MW

Daily Energy: 42,240 kw-hr

Modified Electric

Energy [kw-hr]

Net Grid Energy Input

1.5 MW GT, no net meter

Max turndown=70%

Peak Demand (6a-6p) = 0.33 MW

Daily Energy = 16,190 kw-hr

Application:

1.5 MW Turbine.

Assume max

turndown of 70%

No Export of

electricity to grid

Results:

-Mid-day peak

demand reduced 86%

-Daily Energy need

reduced 62%

-Vast Majority of

chilling load during

operation of turbine

met by absorption

chiller


Combined Heat and Power Installations in Data Center and Communications Facilities

Syracuse University Syracuse NY Microturbine 780 2009 Telecommunications Facility Burlingame CA Microturbine 120 2003

Chevron Accounting Center Concord CA Recip. Engine 3,000 1988

Guaranty Savings Building Fresno CA Fuel Cell 600 2004

Citibank West FSB Building La Jolla CA Microturbine 60 2005

QUALCOMM, Inc. San Diego CA Gas Turbine 11,450 1983/2006

WesCorp Federal Credit Union San Dimas CA Microturbine 120 2003

ChevronTexaco Corporate

Data Center San Ramon CA Fuel Cell 200 2002

Network Appliance Data

Center Sunnyvale CA Recip. Engine 825 2004

Zoot Enterprises Bozeman MT Recip. Engine 500 2003

First National Bank of Omaha Omaha NE Fuel Cell 800 1999

AT&T Basking Ridge NJ Recip. Engine 2,400 1995

Continental Insurance Data

Center Neptune NJ Recip. Engine 450 1995

Verizon Communications Garden City NY Fuel Cell 1,400 2005

Sources: Energy and Environmental Analysis, 2006;

The Role of Distributed Generation and Combined Heat and Power (CHP) Systems in Data Centers EPA/CHP Partnership, August 2007

Case Studies


Fuel Supply

What to do about fuel supply interruptions?

• In SoCAB, all generation will utilize natural gas. • Diesel gen sets restricted to 200 hours total per

year so not viable for general DG/CHP

applications.

• Natural gas supplies are generally not stressed with possible exception of high demand summer

when utility generators have priority

• However, what happens in the event of a disruption of natural gas supplies (earthquake,

fire)?


Fuel Supply

Alternative for combustion systems would be

“pseudo” natural gas

• Propane diluted with air to match Wobbe index of methane/natural gas.

• Propane is stored as liquid: • Large quantities of energy available in small volume • Vapor pressure at ambient is 80 – 150 psig. • suitable for use in many systems without the need for

gas compressors (and associated parasitic losses) in

crucial need periods.

• Long term storage on propane possible.


Fuel Supply

Alternative for combustion systems would be

“pseudo” natural gas

• Syracuse University Data Center uses such a system with Capstone Microturbines.

• Pierce College has similar system for microturbines as a designated emergency

response center.

• Camp Pendleton has (had) a similar system for base operations.


Fuel Supply

Application of diluted propane in fuel cells is more

complex.

• Questions of comparable reformation performance?

• Stored hydrogen works for PEM fuel cells but other systems (PAFC, MCFC, Solid Oxide) utilize

fuel reformation as an integral part of overall

system.


Grid Response

A DG/CHP system for power reliability must be

capable of operation in both grid parallel and

“island” modes.

• Not all DG systems can operate in both modes! • Speed of separation from the grid (< 1 cycle) • Stability of voltage control operation • Reconnection/synchronization with the grid upon

conclusion of outage: can take minutes

• Intelligence to determine if it is safe to reconnect.


Example

Syracuse University Data Center

• 12, 65 kW Capstone Microturbines • CCHP system (absorption chilling and heating) • Rear door cooling • DC Bus • “Hybrid” UPS configuration

• Generation when economically viable • Battery Back-up • Long term generation • Back-up fuel source (propane/air)

• Syracuse University Website: www.syr.edu/greendatacenter/GDC_facts.pdf

http://www.syr.edu/greendatacenter/GDC_facts.pdf


Example

Syracuse University Data Center (cont’d)

• Power delivery to facility Reliability: eight “9”s • 90% overall thermal efficiency possible • IT grade power


Questions?

Please feel free to contact us if you have any

questions:

Pacific Region Application Center /

UC Irvine Advanced Power and Energy Program:

Richard L. Hack – PE, CEM: 949-824-7302 x 122