Fuel Cell Systems for Buildings
US Energy Use and Emissions
Transportation
Industrial
Commercial
Residential
Total Annual US Primary
Energy Use
85.8 Quadrillion Btus
Total Annual US
CO2 Emissions
1460 million metric tons
Combined Heat & Power (CHP)
For Building Applications
Simultaneous production of heat and power for
useful purposes
0.6
7
0.3
3
1
Conventional Electric Power Generation
0.2
0.4
1
0.4
Combined Heat and Power
Fuel Cell Systems for CHP Applications
in Buildings
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Wide size range
Excellent full and part
load performance
Minimal
environmental impact
Simple maintenance
Site friendly
FC System Integration for Buildings
Typical 200kWe/200kWt PAFC System
Exhaust
18%
Heat Recovery
100%
Fuel
Fuel
Processor
85%
Heat
Thermal Energy
40 – 80 C (100 – 175 F)
Fuel Cell Stack
Air & Thermal
Management
42%
Power
Conditioning
2%
40%
40%
Power
5 kWe/9kWt Residential
PEMFC System
Commercially Available 200 kWe PAFC
System
Prototype 100 kWe SOFC System
Fuel Cell CHP System Economics

Cost of electricity ($/kWh)
COE 
 A / P , n , r   CC
8760  LF

Net cost = Capital +
0.05–0.17 0.01–0.08
Basis:
C 1  FC
E
 MC

C 1  F1   T  FC
 E   ALT
Fuel + Maint - HR Credit
0.06 0.01-0.03 0 – 0.03
CC = $500 – $3000/kW
r = 10%
LF = 0.5
E= 45%
T= 40%
FC = $8/MCF
A= 80%
FCCHP Economics: Commercial Bldgs
Cost of electricity, $/kWh
0.2
$3000/kW
0.15
$2000/kW
$1000/kW
NE
0.1
W
$500/kW
M
0.05
S
$1000/kW, 0.8 load fctr
0
0
2
4
6
8
10
Natural gas cost, $/MCF
Basis:
LF = 0. 5
E=0.4
F1 = 0.3
T=0.4
r = 12%
A=0.8
N = 20 years
MC = $0.01/kWh
FC CHP: Residential Buildings
Light &
appliances
24%
Space cooling
5%
Water heating
18%
Space heating
53%
Fuel Cell/Heat Pump/Thermal
Storage CHP System
Heat Rejection, QREJ
Exhaust
Gases
Fuel
FFC
Thermal
Output
QFC
Heat Loss, QL
Residence
Thermal
Storage
Tank
Heat
Pump
Fuel Cell
System
Electric Output
EFC
EESH EAC
Electricity
Thermal Energy
Elect Water Htg, EDW
Thm Water Htg, QDW
Thm Space Htg, QTSH
Elect Space Htg, QESH
Space Cooling, QAC
Supply Fan, EF
Lights and Appl, ELA
Typical House Characteristics
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Floor space:
195 m2 (2100 ft2) on 1-floor
Inside temperature: 21°C(70°F) heating
24°C(75°F) cooling
Unconditioned crawl and attic spaces
4 person family – 2 daytime occupants
Typical residential construction:
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Roof (R-30); Walls (R-11); Floor (R-19)
Double glazed windows with interior blinds
Building infiltration: medium leakage (0.8 ACH)
Selected Locations for Analysis
4
2
3
1
Energy Use For Peak Cooling Day
4.0
Power [kW]
3.5
Legend
3.0
Lights/Appl/Fans Elect
2.5
Electric Space Cooling
2.0
Total Electricity
1.5
Average Summer kWe
1.0
Domestic Water Heating
0.5
0.0
1
3
5
7
9
11 13 15 17 19 21 23
Hour of Day
Atlanta (July 11)
Energy Use for Peak Heating Day
7.0
6.0
Legend
Power [kW]
5.0
Lights / Appl / Fans Elect
4.0
Space Heating Rqmt
3.0
Domestic Water Heating
2.0
1.0
0.0
1
3
5
7
9
11 13 15 17 19 21 23
Hour of Day
Atlanta (Jan 12)
Schematic of FC CHP System
Heat Pump
Subsystem
Fuel Cell
System
TFCC,e
TS,i
Thermal
Storage
Tank
TTS, mTS
TFCC,i
TFCC,x
T
VSD
TCW
TTS
TTSH,i
TDW
THW
Electric energy
Thermal energy
Supplementary
Electric Water Heater
Total Energy System Performance
1
90
0.9
80
0.8
70
0.7
60
0.6
50
0.5
40
0.4
30
0.3
20
0.2
10
0.1
0
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
FCS Part Load Ratio
Atlanta 4.1 kW; Average 1.2 kW
Chicago 5.0 kW; Average 1.5 kW
Sacramento 4.2 kW; Average 1.0 kW
Syracuse 5.0 kW; Average 1.5 kW
Cogeneration Efficiency
Electrical Efficiency
F C S E f fic ie n_c_y
P e rc e n t o f T im e _
_ _]
[%
100
Energy Use by Service
Atlanta
Unavailable
Energy
21.6%
Space
Cooling (EL)
10.3%
Heat
Rejection
12.7%
Syracuse
Space
Heating (EL)
9.7%
Fan/Lights
&Appl
(EL)18.7%
Storage
Tank Loss
3.4%
Water
Heating (TH)
15.4%
Space
Heating (TH)
8.2%
Water
Heating (EL)
0.0%
Annual Fuel Use = 96,530 MJ
Unavailable
Energy
21.5%
Space
Cooling (EL)
2.5%
Space
Heating (EL)
21.3%
Heat
Rejection
2.2%
Storage
Tank Loss
2.5%
Water
Heating (TH)
14.3%
Fan/Lights &
Appl (EL)
14.7%
Space
Heating (TH)
20.9%
Water
Heating (EL)
0.0%
Annual Fuel Use = 126,370 MJ
Comparison of Energy and Life Cycle
Costs to Conventional Systems
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All-electric conventional system components are
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Electric and natural gas conventional system components are
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Electric heat pump
Electric domestic water tank
Electric air conditioner
Natural gas furnace for space heating
Natural gas fired domestic water tank
FC CHP system components are
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Fuel cell system
Thermal storage tank
Electric heat pump
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Life cycle cost function is
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Life of all energy systems is 20 years
Rate of return on capital, r, is 10 percent
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Energy Use and CO2 Emissions
250,000
12,500
200,000
10,000
150,000
7,500
5,000
100,000
2,500
50,000
0
0
Primary energy use, MJ/y
EAC-EH
CO2 emissions, kg/y
EAC-GH
FCCHP
Life Cycle Costs
Life cycle cost, $
20,000
15,000
10,000
5,000
0
EAC-EH
EAC-GH
First Cost
FCCHP
FCCHP
FCCHP
($1500/kW) ($1000/kW) ($500/kW)
Energy Cost
Maintanence Cost
Characteristics of Residential FC CHP
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Residential FC CHP system characteristics:
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FC CHP efficiencies:
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Fuel cell size: 4-5 kWe capacity depending on climatic
conditions
Heat pump performance: SEER of 10
Thermal storage tank size: 300-liter
73 percent in cold climates
63 percent in warmer climates.
FC CHP reduces energy use
FC CHP reduces emissions
FC first cost must be reduced to $500/kWe to yield LCC
comparable to conventional systems
General Prospects for
Building Fuel Cells
 Cost goals (~$500 - $1000/kW) are less stringent than for
vehicles
 Weight and volume criteria are less stringent that for vehicles
 Suitable fuel (natural gas) is widely distributed
 Thermal energy is useful (particularly in residential applications)
 Some building applications already require back-up power source
 No regulatory mandate (like zero emissions vehicle mandate in
California)
 Technological change in building industry is driven by widely
dispersed stakeholders
Integration of Vehicle and Building
Systems
Hydrogen
Storage and
Dispensing
Hydrogen
Vehicle
Electricity
Heat
Natural
Gas
Hydrogen
Fuel processor
Electrolyzer
Questions???