GENERAL INFORMATION - Sustainable Stanfordsustainable.stanford.edu/sites/default/...General_Information_Brochure.pdf · GENERAL INFORMATION . Stanford Energy System Innovations Page

GENERAL INFORMATION

Stanford Energy System Innovations Page 1

Stanford Energy System Innovations

Introduction

The Stanford Energy System Innovations (SESI) project is a $438 million major transformation of the campus district energy system. The transformation is from gas fired combined heat and power with steam distribution to electrically powered combined heat and cooling with hot water distribution. When completed in April 2015, the new heat recovery system will be 52% more efficient than the existing cogeneration system on a pure natural gas basis; or 112% more efficient when state mandated 33% renewable power is factored in. SESI will immediately cut Stanford’s Category I and II GHG emissions in half; save 18% of Stanford’s drinking water supply; and save $300 million (20%) over the next 35 years compared to the existing system.

The heart of SESI is heat recovery- capturing waste heat from the district chilling system to produce hot water for the district heating system. This is depicted in the following charts of daily (summer example) and annual heating and cooling loads.


0102030405060708090

100110120130140150160170180190200210

MM

btu

Hour of Day

Heating

Cooling

Thermal Overlap

-6000

-4000

-2000

0

2000

4000

6000

mm

btu

Stanford UniversityHeat Recovery Potential (2015)

PotentialHeat RecoveryCooling

Heating

Stanford Daily Summertime Heating & Cooling Profile

Stanford Annual Heating & Cooling Profile


Approximately 70% of the waste heat from the chilled water system (currently being discharged out evaporative cooling towers) will be reused to meet 80% of campus heating loads through the use of industrial heat recovery chillers and conversion of the campus heat distribution system from steam to hot water. Converting from steam to hot water also reduces campus heating loads by 10% due to lower distribution line losses. SESI includes:

• Installation of a new electricity powered central energy facility featuring heat recovery; • Demolition of the existing cogeneration plant; • Installation of 20 miles of hot water distribution piping to replace the steam system; • Conversion of 155 building connections from steam to hot water; • Installation of a new campus high voltage substation.

Following are schematics of the SESI system and renderings of the new plant now under construction.

SESI Central Energy Facility 3D Process Schematic


Chiller

Cooling Tower

CWR (52F to 60F)

HeatRecovery

Chiller

Heat Exchanger

Hot Water Storage

Cold Water Storage

Hot Water Generator

Heat Exchanger

Heat Exchanger

Full CEF + GSHE System &

Water Loops

Hot Water

Chilled Water

Condenser Water

Ground Water

HWR(120F to

140F)

HWS(150F to

170F)

CWS (40F to 48F)

60F to 64F

80F to

105F

70F to

85F

38F to 46F(heat

extraction)

76F to 95F(heat

rejection)

60F to 64F

Stanford Replacement Central Energy Facility Renderings

SESI Central Energy Facility Process Schematic


Project Innovations

SESI is unique and innovative in design, implementation and impact. SESI advances heat recovery at a district level, achieving direct environmental improvements and cost savings at a dramatic scale, while paving a flexible and lasting path for Stanford’s sustainability future.

SESI adeptly develops for the first time a highly efficient large scale district energy system based on electricity powered (full path to sustainability) combined heat and cooling rather than fossil fuel fired (questionable path to sustainability) combined heat and power, achieving gas high heating value (HHV) trigeneration efficiency greater than 100% due to the large amount of waste heat recovery. SESI utilizes both large scale hot water and cold water thermal energy storage.

Stanford Replacement Central Energy Facility Site Plan


hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30hrc 1 cw, 21

hrc 1 cw, 0 hrc 1 cw, 0 hrc 1 cw, 0 hrc 1 cw, 0 hrc 1 cw, 0 hrc 1 cw, 0 hrc 1 cw, 0

hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30


hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30 hrc 1 cw, 30

hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30

hrc 2 cw, 0


hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30

hrc 2 cw, 0


hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30 hrc 2 cw, 30

hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30

hrc 3 cw, -

hrc 3 cw, - hrc 3 cw, - hrc 3 cw, - hrc 3 cw, - hrc 3 cw, - hrc 3 cw, - hrc 3 cw, -

hrc 3 cw, -

hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30

hrc 3 cw, -


hrc 3 cw, 30

hrc 3 cw, -

hrc 3 cw, 30 hrc 3 cw, 30 hrc 3 cw, 30

hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, -

hrc 4 cw, -


hrc 4 cw, -

hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, - hrc 4 cw, -

hrc 4 cw, -


hrc 4 cw, -

hrc 4 cw, -

hrc 4 cw, - hrc 4 cw, - hrc 4 cw, -

chl 1, 25 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 33 chl 1, 36 chl 1, 36

chl 1, 36

chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36

chl 1, 36

chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36 chl 1, 36

chl 1, 12

chl 1, 36 chl 1, 36

chl 1, 36

chl 1, 36 chl 1, 36

chl 1, 13 chl 1, 21 chl 1, 17

chl 1, -

chl 1, 36

chl 1, 36

chl 1, 36

chl 1, 36 chl 1, 24

chl 1, 16

chl 2, -


chl 2, -

chl 2, 36 chl 2, 36

chl 2, 36

chl 2, 36 chl 2, 36 chl 2, 36 chl 2, 28

chl 2, 36 chl 2, 36 chl 2, 36

chl 2, 36

chl 2, 36 chl 2, 31 chl 2, 14

chl 2, 1

chl 2, 36 chl 2, 36 chl 2, 36 chl 2, 36 chl 2, 36 chl 2, 36 chl 2, 36 chl 2, 36

chl 2, -

chl 2, 1

chl 2, 35

chl 2, 36

chl 2, 36 chl 2, 36

chl 2, -chl 2, -

chl 2, -

chl 2, -

chl 2, 36

chl 2, 36

chl 2, 36

chl 2, 1

chl 2, -chl 2, -

chl 3, -


chl 3, -

chl 3, 3 chl 3, 6

chl 3, 36

chl 3, 36 chl 3, 36 chl 3, 36

chl 3, -

chl 3, 36 chl 3, 36 chl 3, 36

chl 3, 36

chl 3, 20

chl 3, -

chl 3, -

chl 3, -


chl 3, 8

chl 3, -

chl 3, -

chl 3, -

chl 3, 36

chl 3, 36 chl 3, 36

chl 3, -chl 3, -

chl 3, -

chl 3, -

chl 3, 36

chl 3, 3

chl 3, 16

chl 3, -

chl 3, -chl 3, -

chl 4, -


chl 4, -

chl 4, - chl 4, -

chl 4, 36

chl 4, 36 chl 4, 36 chl 4, 36

chl 4, -

chl 4, 36 chl 4, 36 chl 4, 36

chl 4, 36 chl 4, -

chl 4, -

chl 4, -

chl 4, -


chl 4, -

chl 4, -

chl 4, -

chl 4, -chl 4, 36

chl 4, 36 chl 4, 36

chl 4, -chl 4, -

chl 4, -

chl 4, -

chl 4, 22

chl 4, -

chl 4, -

chl 4, -

chl 4, -chl 4, -

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes0

cw from tes40

cw from tes72

cw from tes114

cw from tes131

cw from tes135

cw from tes216

cw from tes135 cw from tes

123 cw from tes106

cw from tes8

cw from tes-

cw from tes0

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes-

cw from tes0

cw from tes-

cw from tes0


68

cw from tes72

cw from tes216


216

cw from tes216

cw from tes56

cw from tes-

cw from tes-

cw from tes-

cw from tes- cw from tes

-

unmet cw demand, 0

unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

unmet cw demand, 0

hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42hrc 1 hw, 29

hrc 1 hw, 0

hrc 1 hw, 0hrc 1 hw, 0 hrc 1 hw, 0 hrc 1 hw, 0

hrc 1 hw, 0

hrc 1 hw, 0

hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42

hrc 1 hw, 0hrc 1 hw, 0


hrc 1 hw, 0

hrc 1 hw, 0

hrc 1 hw, 0

hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42 hrc 1 hw, 42

hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42

hrc 2 hw, 0

hrc 2 hw, 0


hrc 2 hw, 0

hrc 2 hw, 0

hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42

hrc 2 hw, 0



hrc 2 hw, 0

hrc 2 hw, 0

hrc 2 hw, 0

hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42 hrc 2 hw, 42

hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42

hrc 3 hw, 0

hrc 3 hw, 0


hrc 3 hw, 0

hrc 3 hw, 0

hrc 3 hw, 0

hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42

hrc 3 hw, 0



hrc 3 hw, 0

hrc 3 hw, 0

hrc 3 hw, 0

hrc 3 hw, 42

hrc 3 hw, 0

hrc 3 hw, 42 hrc 3 hw, 42 hrc 3 hw, 42

hrc 4 hw, 0

hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0


hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0 hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0


hrc 4 hw, 0


hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

hrc 4 hw, 0

htr 1, 0

htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0htr 1, 0 htr 1, 0 htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0 htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 2

htr 1, 0htr 1, 0

htr 1, 0htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0

htr 1, 0htr 1, 0

htr 2, 0


htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0htr 2, 0 htr 2, 0 htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0


htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0htr 2, 0

htr 2, 0htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0

htr 2, 0htr 2, 0

htr 3, 0


htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0htr 3, 0 htr 3, 0 htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0


htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0htr 3, 0

htr 3, 0htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0

htr 3, 0htr 3, 0

htr 4, 0


htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0htr 4, 0 htr 4, 0 htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0


htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0htr 4, 0

htr 4, 0

htr 4, 0htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

htr 4, 0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes53

hw from tes79

hw from tes76

hw from tes74

hw from tes71

hw from tes71

hw from tes71

hw from tes71

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes0

hw from tes38

hw from tes82

hw from tes79

hw from tes76

hw from tes74

hw from tes74

hw from tes76

hw from tes79

hw from tes0

hw from tes0

hw from tes0

hw from tes0 hw from tes

0

unmet hw demand, 0

unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

unmet hw demand, 0

(1,600)

(1,200)

(800)

(400)

-

400

800

1,200

1,600

(400)

(300)

(200)

(100)

-

100

200

300

400

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:0

0

11:0

0

12:0

0

13:0

0

14:0

0

15:0

0

16:0

0

17:0

0

18:0

0

19:0

0

20:0

0

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0

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0

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0

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:0

0

11:0

0

12:0

0

13:0

0

14:0

0

15:0

0

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0

17:0

0

18:0

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0

20:0

0

21:0

0

22:0

0

23:0

0

mm

btu

(line

cha

rt)

mm

btu

(bar

cha

rt)

hrc 1 cw hrc 2 cw hrc 3 cw hrc 4 cw chl 1 chl 2 chl 3 chl 4cw from tes unmet cw demand hrc 1 hw hrc 2 hw hrc 3 hw hrc 4 hw htr 1 htr 2htr 3 htr 4 hw from tes unmet hw demand total cw demand total hw demand cw storage balance hw storage balance

Wednesday, July 15, 2020 Thursday, July 16, 2020

Stanford UniversityCentral Energy Plant Optimization Model (CEPOM)

CEF Dispatch

SESI combines cutting edge technology from both North American and European district energy systems:

North America o Overall system design (AEI- Affiliated Engineers, Inc.) o Architects (ZGF) o Structural/Geotechnical (Rutherford + Chekene) o Construction (Whiting Turner) o Heat recovery chillers & chillers (York) o Controls (JCI) o HW system design & operations consultation (District Energy St. Paul) o HW generators (Cleaver Brooks) o Peer review (Jacobs Carter Burgess, Black & Veatch, Enginomix, Navigant) o GSHE/Steam to Hot Water Conversion Consultation (Ball State Univ.; Univ. of

British Columbia) Europe

o HW system design & operations consultation (COWI Denmark, FVB Sweden) o HW distribution piping system (LOGSTOR Denmark) o HW system modeling (Termis 7T/Schneider Electric Denmark) o Building HW-HW heat exchangers (Alfa Laval Sweden) o Substation components (Siemens Italy)

Another SESI innovation is new software and services for optimizing the planning, design, and operation of combined heating and cooling plants with both hot and cold thermal energy storage (TES). It provides predictive load forecasting, economic dispatching, and full plant optimization and automation tools which did not exist but were invented at Stanford for SESI. These new services and software are being further developed by a new startup company to provide new tools to central energy plants of all types to improve their energy and economic efficiency.


SESI Heat Recovery with Hot Water System Energy Schematic

2,151,012 mmtu

36.7 lb

1,097,016 mmbtu

Heat Recovery Chiller

(COP = 6.30)(1.327 kw/ton)

61,238,537 kwh

46,148,106 ton-hr

762,781 mmbtu

Cogeneration Efficiency (electricity + heating)

= 74.8%

Heating

Electricity

Gas in

321,422,769 kwh

Gas Power Plant Efficiency

1,097,016 mmbtu2,151,012 mmbtu = 51.0%

22,320,894 ton-hr

330,259 mmbtuBoiler

Heating

10,539,926 kwh

388,540 mmtuGas in

HRC Chilling @ 1.327 kw/ton

Electric Chilling @

.4722 kw/ton

849,782 mmbtu

248,983,788 kwh248,983,788 kwh

1,900,782 mmbtu2,539,552 mmbtu

267,851 mmbtu35,973 mmbtu

Waste heat to atmosphere

364,362mmbtu


1,053,996 mmbtu

660,518 kwh2,254 mmbtu

Waste heat to environment

(distribution line loss)

42,040 mmbtu

= 104.3%1,900,782 mmbtu1,822,548 mmbtu

‘Relative’ Gas Cogeneration Efficiency with 33% Renewable Electricity

(electricity + heating)

Total usable heat out = 1,051,000 mmbtu

Total usable electricity out = 849,782 mmbtu

Total usable heat & power (cogeneration work) out =

1,900,782 mmbtu

553,777 mmbtu

Total usable chilling out = 821,628 mmbtu

Total usable heat, power, & chilling (trigeneration work) out

= 2,722,410 mmbtu

Trigeneration Efficiency (electricity + heating + cooling)

= 107.2%2,722,410 mmbtu2,539,552 mmbtu

= 149.4%2,722,410 mmbtu1,822,548 mmbtu

‘Relative’ Gas Trigeneration Efficiency with 33% Renewable Electricity(electricity + heating + cooling)

Total natural gas consumed @ 100% fossil power = 2,539,552 mmbtu

Total natural gas consumed @ 67% fossil power + 33% renewables =

1,822,548 mmbtu

Improved Energy Efficiency

SESI’s primary energy efficiency benefits come from substantial utilization of waste heat, followed by reducing heating distribution system line losses through the conversion from steam to hot water. By utilizing waste heat and lowering line losses, SESI is expected to achieve an overall system trigeneration (power, heating, and cooling) efficiency of 107% on a natural gas high heating value (HHV) basis, if paired with average 51% efficient (6700 btu/kwh heat rate) grid gas power generation over its 30 year life cycle. While the current average heat rate of base load gas fired electricity generation in California is over 7100 (~48% HHV efficiency) this is expected to continue to improve as older plants are retired (ref: THERMAL EFFICIENCY OF GAS-FIRED GENERATION IN CALIFORNIA, Michael Nyberg, California Energy Commission, August 2011). Over the next 30 years an average heat rate of 6700 (~51% efficiency), equivalent to that of current new state base load gas generating plants being installed today (ref Oakley Generating Station, et.al.) appears a reasonable forecast.

However given California’s 33% Renewable Portfolio Standard (RPS) requirement the overall effective natural gas trigeneration efficiency of SESI is 149% as shown below.


BAU- Cardinal Cogeneration

4,400,000 mmbtu

Electricity

Total = 2,643,775 mmbtu

248,983,788 kwh

Gas in

Cogeneration Efficiency(electricity + heating )

1,900,782 mmbtu3,860,868 mmbtu

= 49.2%

849,782 mmbtu

Cogeneration Efficiency(electricity + heating)

2,643,775 mmbtu4,400,000 mmbtu = 60.0%

Electric Chilling @ .66

kw/ton31,285,190 kwh

CogenHeating

BoilerHeating

Steam Chilling @

12.18 lb/ton

1,062,255 mmbtu

-105,943,244 kwh-361,584 mmbtu

254,000 mmbtu

-708,988 mmbtu

Gas saved

Gas in169,856 mmbtu

New Grid Gas Power Plant Efficiency

361,584 mmbtu708,988 mmbtu = 51.0%

1,316,255 mmbtu


47,691,222 ton-hr

20,777,778 ton-hr

1,062,255 mmbtu

135,885 mmbtu

388,960,000 kwh

1,327,520 mmbtu


248,983,788 kwh-347,404 mmbtu


1,756,225 mmbtu 1,225,753 mmbtu

249,333 mmbtu

572,295 mmbtu106,773 mmbtu

2,747,778 kwh9,378 mmbtu

Waste heat to environment

(distribution line loss)

147,140 mmbtu

Total usable heat & power (cogeneration work) out =

1,900,782 mmbtu

Total usable heat, power, & chilling (trigeneration work) out

= 2,722,410 mmbtu

Trigeneration Efficiency(electricity + heating + cooling)

2,722,410 mmbtu3,860,868 mmbtu

= 70.5%

Total usable heat out = 1,051,000 mmbtu

Total usable electricity out = 849,782 mmbtu

Total usable chilling out = 821,628 mmbtu

Total natural gas consumed @ 100% fossil power = 3,860,868 mmbtu

A similar energy schematic for the existing Cardinal Cogeneration plant serving Stanford shows that it consumes 112% more gas than the SESI plant will (3.8 mil mmbtu vs 1.8 mil mmbtu per year) to meet campus energy needs, with 33% renewables factored in as required under the California RPS.

Financial Advantages

Nine major options for Stanford’s next energy system were developed in detail, including:

• gas fired cogeneration and steam distribution (business as usual Third Party vs. Stanford owned & operated)

• gas fired cogeneration with hot water distribution • hybrid cogeneration + heat recovery with hot water distribution (Turbine and IC engine

options) • heat recovery plant with hot water distribution (Grid + Heat Recovery option) • conventional boilers and chillers central plant (Grid, No Heat Recovery option) • Grid + Heat recovery plant with 20% to 33% on-site PV power


$153

$435

$549 $579

$546

$474 $449

$546 $593

$1,593

$1,356 $1,392 $1,399

$1,333 $1,290

$1,371

$1,276 $1,267

-0.2

0.4

1.0

1.6

2.2

2.8

3.4

4.0

4.6

5.2

5.8

6.4

7.0

7.6

8.2

8.8

9.4

10.0

-$100

$200

$500

$800

$1,100

$1,400

$1,700

$2,000

1. Business AsUsual

2. New Cogen(Steam)

3. New Cogen(HW)

4. Gas Power(Turbine) + Heat

Recovery

5. Gas Power (ICEngines) + Heat

Recovery

6. Grid + HeatRecovery

7. Grid, No HeatRecovery

8. Grid + 20%PhotovoltaicPower + Heat

Recovery

9. Grid + 33%PhotovoltaicPower + Heat

Recovery

GHG

(mill

ion

tons

); W

ater

(mill

ion

ccf)

NPV

201

5-20

50 (

Mill

ions

)

Stanford UniversityCentral Energy Facility Replacement Options

Electricity

Natural Gas

O&M

Capital

Water used (ccf)

Total GHG

Steam Options Hot Water Options

Heat Recovery Options

On-site Gas Cogeneration Options Grid Power Options Grid + On-site PV Options

These options were modeled for energy and exergy efficiency, economics, and environmental impact and subjected to substantial peer review. Results are presented in the chart below which compares the life cycle cost of each option as well as the relative GHG emissions and water use. Based on these results Stanford selected the electrically powered combined heat & cooling plant with hot water distribution (option 6) as its new base energy system and is advancing study on the feasibility of adding some amount of on-site PV power to the scheme.

As shown the selected option, heat recovery + hot water distribution represents the lowest life cycle cost and also presents one of the lowest up front capital cost options since on-site power generation infrastructure is avoided. Despite requiring significant up front capital investment and significant disruption to the campus during the four year installation phase (2012 -2015), SESI received widespread support from faculty, administration, and the Board of Trustees and is now under construction


Project Challenges

SESI is a complete transformation of Stanford’s district energy system from gas fired combined heat and power (CHP) to electricity powered combined heat and cooling (CHC). Because of the popularity of gas fired cogeneration as a presumed best practice in district energy and Stanford’s previous reliance on it, SESI was initially met with considerable skepticism from faculty, administration, and even current campus utilities staff. Much explanation, education and peer review throughout 2010, 2011 and 2012 provided the business case to stakeholders to demonstrate why SESI and CHC is a superior option to continued CHP for Stanford University.

The scale of physical disruption to the university was also a major concern and required many meetings to explain the project and coordinate work with a very large and diverse campus research and residential community. Given the simultaneous construction of a new adult hospital and major expansion of the children’s hospital further considerable coordination and regulatory approvals were needed to assure protection of patient care and other hospital functions during the transformation.

SESI Building Conversion and Steam-To-Hot Water Conversion Phases


-6000

-4000

-2000

0

2000

4000

6000

mm

btu

Stanford UniversityHeat Recovery Potential (2015)

PotentialHeat RecoveryCooling

Heating

Potential for Ground Source Heat Exchange

Potential for Ground Source Heat Exchange

Looking Ahead

Several potential enhancements to SESI are being investigated by Stanford at this time.

Ground Source Heat Exchange

Ground Source Heat Exchange (GSHE) could augment the basic heat recovery scheme of SESI by providing a more sustainable way to meet the 20% excess winter heating and 30% excess summer cooling needs of the university that can’t be met by building heat recovery. Phase I studies indicate that GSHE at Stanford is feasible. The university is now in Phase II studies that include exploratory borings to fully map subsurface hydrogeology, regulatory reviews, and other tasks necessary to determine the final feasibility of a GSHE addition to SESI.


On-site Photovoltaic Power

Stanford has completed preliminary planning and economic analysis of the installation of a significant amount of photovoltaic power on campus buildings, parking lots, and parking structures and is now in final design and negotiations with a major solar company for a potential major campus PV project.


0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

MW

of E

lect

ricity

Dem

and

hour of day

Campus Electricity Demand Management StrategiesBuilding Demands CEF Demand (CEPOM Limited)

Micro Demand Management(see next page)

Macro Demand Management(CEPOM Limits CEF Demand to

Complement Expected Max Building Demands)

Building Electrical Demands

CEF Electrical Demands

Electricity Storage

Macro level control of Stanford’s demand on the regional electrical grid will be managed by the new CEPOM control system1 at the Central Energy Facility.

However opportunities for mid- and micro-level management of Stanford’s grid electrical profile and increased economic performance exist through the deployment of on-site Electricity Storage (ES). The potential incorporation of more transient on-site electrical supplies (e.g. on-site PV generation) and loads (e.g. plug-in-electric vehicles) further enhance the consideration of ES for the reliability and economic performance of Stanford’s energy system.

1 CEPOM will utilize thermal energy storage and selective equipment dispatching based on a combination of electricity commodity and demand prices to achieve optimum economic performance of the campus energy system while assuring all thermal loads are met.


-

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

MW

of E

lect

ricity

Dem

and

hour of day

Campus Electricity Demand Management StrategiesBuilding Demands with 10MW PV CEF Demand (CEPOM Limited) Building Demands without PV Building Spike Total Campus Spike

Building Electrical Demands

CEF Electrical Demands

Addition of 10 MW PV generation helps significantly lower (by 6 MW) overall campus demand and CEPOM would respond to limit CEF to complement revised net building demands accordingly.

However, because PV generation could have short term volatility of a magnitude much greater than potential building spikes (5 to 10 MW vs 1 to 2 MW) on a number of days during the year, adept micro level demand management would be desirable with PV and other transient electrical loads .

Initial studies have confirmed the economics of deploying ES at the university, and this has led to consideration of novel approaches in how it might best be deployed. One chronic challenge at Stanford and other universities is the building emergency generator fleet. Emergency electrical generation at specific buildings is required for operation of life/safety systems and to protect high security/high value activities such as research. This is typically met by installing diesel powered emergency generators at the buildings as shown in the figure below, however these are difficult to air permit; expensive to purchase, operate and maintain; and provide very little actual service over their lifetime. Trying to derive more value out of this very expensive stand-by emergency power generation fleet is a constant goal, but air permit limits and the impacts of localized campus noise and air pollution typically preclude discretionary operation of these units to serve the campus in non-emergency situations.


Building 1

Building 2

Building 3

Building 4

Building 5

Building 6

Substation

60kV

12kV

Circuit Breaker (closed)Circuit Breaker (open)Circuit Breaker with Emergency Power Backup (closed)

Normal Operation (Existing)

Diesel Generators(>100 each, >30 MW capacity)

off off off off off off

Given the attractiveness of on-campus electrical storage and the challenge of sustaining diesel powered emergency generators Stanford is examining the feasibility of replacing emergency generators with distributed electrical storage. Under this concept if power to a building were interrupted a distributed electrical storage device (battery) would discharge electricity to it instead of an emergency generator. Before the battery is drained a mobile refueling device (truck mounted capacitor or battery system) would recharge it to provide continuous uninterrupted emergency power to the facility for as long as required. With the advent of electric busses and cars employment of Vehicle-To-Grid strategies to allow the campus electric vehicle fleet to recharge distributed electrical storage may also become possible.

Upon the loss of off-site power to the university centralized dual-fuel capable power generators would provide electricity to emergency loads in buildings. This would be achieved by the use of ‘smart circuit breakers’ at the buildings that disconnect non-essential loads from the campus grid but keep emergency circuits closed in to receive power from the central emergency generation source. Because centralized emergency generation could be powered by natural gas it also could be permitted for use as base load power generation as desired for replacing or augmenting grid power. For these reasons Stanford is investigating replacing its current Distributed Emergency Generation (DEG) system with a Centralized Emergency Generation and Distributed Electrical Storage (CEGDES) system. The following figures illustrate the CEGDES concept now being explored by Stanford University.

Stanford University

Distributed Emergency Generation System


Building 1

Building 2

Building 3

Building 4

Building 5

Building 6

Substation

60kV

12kV

Emergency Operation(Existing)

(single building outage)

off off off on off off

X



Emerg. Powerto Building

Building 1

Building 2

Building 3

Building 4

Building 5

Building 6

Substation

60kV

12kV

Emergency Operation(Future?)

(single building outage)

Batteries

Central Emergency Generators(Flex Fuel Natural Gas or Diesel)


off

Standby/Load Management





X

Mobile Recharging as required

Distributed Emergency Generation

Centralized Emergency Generation and Distributed Electrical Storage


Building 1

Building 2

Building 3

Building 4

Building 5

Building 6

Substation

60kV

12kV

on on on on on on

Emergency Operation(Existing)

(campus wide power outage)

X



Building 1

Building 2

Building 3

Building 4

Building 5

Building 6

Substation

60kV

12kV

Emergency Operation(Future?)

(campus wide power outage)

Batteries

Central Emergency Generators(Flex Fuel Natural Gas or Diesel)








XonUpon detection of a loss of off-site power at the substation, non-essential building

circuit breakers open, then reclose automatically when restoration of off-site power flow (upstream of campus central

emergency generators) is detected

Upon campus wide loss of off-site power, central emergency

generators power only essential building circuits via campus grid

Distributed Emergency Generation

Centralized Emergency Generation and Distributed Electrical Storage


Electricity Supply

Upon retirement of the existing Cardinal Cogeneration plant in 2015 Stanford will rely primarily on electricity supplied by the California grid. Having achieved Direct Access to the state’s electricity markets the university is now in a position to control its power portfolio and shape its future energy supply to meet the risk, economic, and environmental profile established by university leadership. Work to develop this long term electricity supply strategy and initiate the power procurement process will begin in the fall of 2013.

Conclusion

In addition to teaching, research, and public service in the field of sustainability Stanford University is committed to practicing sustainability in its own operations and is making significant transformations of the campus toward that goal. The Stanford Energy System Innovations program is but one example and will provide the university an efficient, economic, and sustainable energy system for the 21st century.

More information on SESI may be found at: http://sustainable.stanford.edu/sesi

A copy of this report may be found at: http://sustainable.stanford.edu/sesi-technical

For more information please also feel free to contact:

Joseph Stagner, P.E. Executive Director Department of Sustainability and Energy Management Land, Buildings & Real Estate Stanford University 327 Bonair Siding Stanford, CA 94305-7255 650-721-1888 (work) [email protected]

http://sustainable.stanford.edu/sesi

http://sustainable.stanford.edu/sesi-technical

mailto:[email protected]

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