towards systemic analysis of building energy systems...environmental energy technologies division...

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Environmental Energy Technologies Division

Towards Systemic Analysis of Building Energy Systems

seminar presented at the

Carnegie Mellon UniversityElectricity Industry Center

30 May 2006by

Chris Marnay

research supported by the U.S. Dept of Energy and the California Energy Commission

der.lbl.gov eetd.lbl.gov/ea/emp [email protected]

collaborators: Afzal Siddiqui, Karl Maribu, Kristina Hamachi LaCommare, Michael Stadler, Ryan Firestone

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Outline

1. Introduction to Microgrids

2. Distributed Energy Resources Customer Adoption Model (DER-CAM)

3. Example Study: San Bernardino CA USPS P&DC (parts A & B)

4. Power Quality and Reliability (PQR)

5. Lessons Learned/Future Work

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History of U.S. Electricity Sector

phases of centralization

1. isolated developments (pre 1900)

2. consolidation and monopolization (1900-1933)

3. fossilization and total centralization (1933-1980)

phases of decentralization

1. independent investment (avoided cost) (1980-1995)

2. wholesale (and some retail) competition (1995- )

3. decentralization and full competition? (2000- )

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What is a Microgrid?

A controlled grouping of energy (including electricity) sources and sinks that is connected to the macrogrid but can function independently of it.

Two Main Benefits to Developers of Microgrids:• pushing efficiency limits by heat recovery (CHP)• providing heterogeneous power quality and

reliability (PQR)

There are other societal benefits.

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2. Distributed Energy Resources Customer Adoption Model

(DER-CAM)

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DER Customer Adoption Model (DER-CAM)

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DER-CAM:Mathematical Model

• DER-CAM uses GAMS to model an MIP solved with Cplex • minimize

– customer (annual) energy bill(DER investment, DER operation, energy purchases,

energy sales) annualized• subject to:

– energy balance– electricity & NG tariffs– DER characteristics (investment cost, heat rate, and maintenance cost)– heat production/available waste heat/CHP technology

(heat storage & solar thermal assistance)– solar insolation

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3. San Bernardino Processing and Distribution Center

Part A: 2002

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Redlands, California

San Bernardino USPS, Redlands CA

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San Bernardino USPS: Temperature

source: Renewable Resource Data Center, National Renewable Energy Laboratory, http://rredc.nrel.gov/

05

1015202530354045

1 2 3 4 5 6 7 8 9 10 11 12Month

deg

C

Minimum Temp (degC)Average Temp (degC)Maximum Temp (degC)

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San Bernardino USPS, Redlands CA

equipment runs mostly during evening and night

25 000 m2 single-story

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USPS July Weekday Electric Loads

site electric loads

How site electric loads are met.

peak load = 1500 kW

0200400600800

1000120014001600

1 4 7 10 13 16 19 22

hour

load

(kW

e)

CoolingElectric-Only

0

200

400

600

800

1000

1200

1400

1600

1 3 5 7 9 11 13 15 17 19 21 23

hour

load

(kW

e)

cooling offset by gas burningcooling offset by waste heat recoveryutility electricity purchaseNG generator generationMT generation

peak load = 1150 kW

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San Diego USPS(Margaret L. Sellers Processing and Distribution Center)

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East Bay Municipal Utility District Microturbine Installation with Cooling

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3. San Bernardino Processing and Distribution Center

Part B: 2005

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San Bernardino USPS: Solar Radiation

0

5001000

1500

2000

2500

3000

3500

1 2 3 4 5 6 7 8 9 10 11 12month

J/cm

^2/d

ay

Fukuoka, JapanSan Joaquin Valley, CA

source: 2001 data from World Radiation Data Centre, http://wrdc.mgo.rssi.ru/

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Minimum Cost Results• low temp. collectors are economic• chosen system:

– 1 MW (electric capacity) of reciprocating engines– 1.7 MW (thermal cooling capacity) single-effect abs. chiller– 1.5 MW (heat delivered) low temperature collectors

• but only provide 45% of heat• and only lower the annual bill by 1%• high temp. collectors and PV are not chosen

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Meeting Absorption Chiller and Electric Loads

0

500

1000

1500solarDG

absorption chiller thermal load

$500/kWhigh temp. July

US$150/kW low temp. Jan

elec

tric

pow

er (k

W)

0

500

1000

1500

1 5 9 13 17 21hour

solarDG

ther

mal

pow

er (k

W)

0

500

1000

1500

NG-fired DGpurchase

offset by abs.

0

500

1000

1500

1 5 9 13 17 21hour

offset by abs. chiller

purchased

NG-fired DG

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Deteriorating Economics of DG-CHP2002 2004 2006

summer winter summer winter summer winterelectricity

monthly fee ($) ~300 ~300 ~300 ~300 ~300 ~300demand charge noncoincident 6.6 0.0 8.3 8.3 8.5 8.5($/kW monthly peak)on-peak 18.0 0.0 21.7 0.0 29.7 0.0

mid-peak 2.7 0.0 3.3 0.0 4.8 0.0off-peak 0.0 0.0 0.0 0.0 0.0 0.0

volumetric charge on-peak 0.195 n/a 0.122 n/a 0.163($/kWh) mid-peak 0.109 0.121 0.072 0.091 0.094 0.118

off-peak 0.088 0.089 0.041 0.043 0.054 0.056natural gas

monthly fee ($) ~600 ~600 ~600 ~600 ~600 ~600volumetric ($/kWh) 0.014 0.013 0.02 0.021 0.024 0.024($/GJ) 3.89 3.61 5.56 5.83 6.67 6.67

to to to to to to($/kWh) 0.02 0.023 0.026 0.028 0.032 0.041($/GJ) 5.56 6.39 7.22 7.78 8.89 11.39

on-site generation marginal cost

electricity only 0.042 0.039 0.061 0.064 0.073 0.073($/kWh) to to to to to to

0.061 0.070 0.079 0.085 0.097 0.124electricity and absorption cooling 0.039 0.037 0.056 0.059 0.068 0.068($/kWh) to to to to to to

0.056 0.065 0.073 0.079 0.090 0.116

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Optimal System Results (130 g/kWh)

NG

ICE*

Abs. chiller**

Heat

exchanger***

Solar collector****

Total

DER

Maint-enance

Elec-tricity

Natural G

as

Electricity

Natural gas

no investment 0.0 0.0 0.0 0.0 932 0 0 930 2 9770 13.9 1271CHP, no solar 1.0 1.7 1.1 0.0 813 58 37 437 281 6092 9326 1277low temp. $150/kW 1.0 1.7 1.1 1.5 802 75 35 426 266 5224 10197 1236high temp. $500/kW 1.0 1.6 0.9 0.8 798 95 32 424 247 5886 8168 1190high temp. $900/kW 1.0 1.6 0.6 0.1 819 69 24 515 211 6933 6825 1256

* capacity in units of 0.5 MW engines**

*** capacity in units of rated thermal power transfer**** capacity in units of thermal power production at 1 kW/m^2 solar radiation

Installed Capacity (MW) Energy cost (k$/a) Energy purchase (MWh/a)

chiller capacity stated as amount of thermal power consumed. Chillers are single effect for the low temp. case and double effect for the high temp. cases.

Carbon emissions

(t/a)

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Carbon Constraint Results• high temp. collectors provide carbon

savings at lower control cost than low temp. collectors

• for low carbon reductions PV is…– more economic than high temp. collectors– competitive with low temp. collectors

• solar thermal is still valuable because of storage which offsets evening cooling loads

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DER Equipment Installation Under Carbon Constraint (130 g/kWh)

low temp. collector high temp. collector

01234567

600 800 1000 1200carbon emissions (t/a)

inst

alle

d ca

paci

ty (M

W)

solar collector PV NG-fired DG

01234567

600 800 1000 1200carbon emissions (t/a)

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Pareto Minimization of Cost and Carbon Emissions (130 g/kWh)

0

500

1000

1500

2000

2500

3000

0 500 1000 1500carbon limit (t/a)

cost

(US

k$/a

)

Low Temp.collectorsHigh Temp.collectors

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Cost of Carbon Savings (130 g/kWh)

00.20.40.60.8

11.21.41.61.8

2

0 200 400 600 800 1000carbon savings (t/a)

cost

of c

arbo

n sa

ving

s (U

S$/

kg) Low Temp.

collectorsHigh Temp.collectors

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Source of Carbon Emissions(130 g/kWh)

0200400600

800100012001400

700 800 900 1000 1100 1200 1238

carbon limit (t/a)

carb

on e

mis

sion

s (t/

a)

Carbon Emissioncarbon emissions from natural gas carbon emissions from utility electricity

low temp. collector high temp. collector

0200400600

800100012001400

600 700 800 900 1000 1100 1200

carbon limit (t/a)

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4. Power Quality and Reliability

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Electricity Reliability, Technology, and Cost (Traditional)

stand-alonesteam generation

1900 1950 2000

Year

LightsMotors

Digital Systems

electricity reliability(nines)

109876543210

(3 ms/yr)

(30 ms/yr)

(0.3 sec/yr)

(3 sec/yr)

(30 sec/yr)

(5 min/yr)

(1 hr/yr)

(9 hr/yr)

(3-4 day/yr)

(1 mo/yr)

interconnected central station generation

grid + back-up + UPS

cost ($/kWh)

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1900 1950 2000

Year

electricity reliability(nines)

109876543210

(3 ms/yr)

(30 ms/yr)

(0.3 sec/yr)

(3 sec/yr)

(30 sec/yr)

(5 min/yr)

(1 hr/yr)

(9 hr/yr)

(3-4 day/yr)

(1 mo/yr)

cost $/kWh

DER-basedDistribution System

Robust Gen. & Trans.

Local Reliability

Electricity Reliability, Technology, and Cost (Distributed)

UPS/microgrids

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What Does Power Quality and Reliability Really Cost?

lowest in w

orld today→

U.S. today

→perfection

→

cost of unreliability→

total cost of reliability

→

possible effect of DER

cost of reliability→

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Temporal Electricity Price Variation is Familiar

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An PQR Pyramid• Loads are often broken

down by time and enduse but not by PQR requirements.

• The most demanding PQR requirements are not met.

• Highly sensitive loads are small and they could be smaller.

• Local supply could tailor PQR to the needs of the enduse.

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5. Lessons Learned/Future Work/Conclusion

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Lessons Learned

• reciprocating engines are the strongly incumbent technology• mixed technology systems sometimes economically attractive• DER economics are driven more by electricity than fuel prices• optimal systems are larger than are typically built today• DER-CAM sizes more to meet electricity than heat loads• in moderate climates, cooling loads can justify CHP systems• PV becomes economic with subsidies or carbon constraints• demand charges encourage bigger systems• energy efficiency gains significant when CHP involved, but

modest overall • efficiency constraints can run counter to system economics• markets are highly regionalized and building specific

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DER-CAM On-Going Work• bottom up modeling of effects of DER/microgrid

adoption (environmental/PQR?)• evaluating economics of microgrid technology

improvements • extending storage capability to electricity• estimation of national benefits of U.S. DER

adoption and DG R&D• development of EnergyManager capabilities• applying algorithms in Energy+• PQR valuation

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Conclusion• DER-CAM has been developed to identify cost minimizing technology neutral microgrid systems

• useful energy flow requirements are met systemically by equipment investments and operations, including CHP and endogenous effects

• devices/investments interaction endogenously solved

• results provide valuable starting point yardstick for building analysis or can be generalized to produce higher level estimates of DER adoption

• incorporating PQR is the big challenge

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THE END

towards systemic analysis of building energy systems...environmental energy technologies division...

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