NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

National Hydrogen 

Association Meeting

Darlene M. Steward 

Mike Penev

National Renewable 

Energy Laboratory

Columbia, SC

March 30 – April 3, 2009

NREL/PR-560-45628

The Influence of Building Location on Combined Heat and 

Power/ Hydrogen (Tri-Generation) System Cost, Hydrogen 

Output and Efficiency

This presentation does not contain any proprietary, confidential, or otherwise restricted information
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Acknowledgements

Development of the H2A Power Model has been funded 

by the DOE Office of Energy Efficiency and 

Renewable Energy through a contract with the 

National Renewable Energy Laboratory

Mike Penev, the co-author on this work, was 

instrumental in development of the energy model 

presented here.
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Introduction

Goals:

Analyze the influence of building type and location on 

the economics of Combined Heat and Power/ 

Hydrogen (Tri-Generation) systems.

Identify building type (electricity and heat load) 

characteristics that are favorable for Tri-Generation 

applications

Identify geographic characteristics that are favorable or 

un-favorable for tri-generation applications
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Combined Heat & Power / Hydrogen Production Cost Model Allows 

Analysis of New Transition Strategies

Hydrogen infrastructure costs for the early transition phase are 

large, and are relatively high risk due to uncertainty of demand

Combining hydrogen production with CHP capability may reduce 

upfront costs and reduce investment risks

Fuel Cell

with CHP

Electricity

Natural Gas

Power

Heat

Natural Gas

or Biogas

Hydrogen
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Combined Heat & Power / Hydrogen Production Concept

System provides both electricity and heat; replaces 

electricity from the grid and heat from a furnace or 

boiler

– More efficient; Heat from the facility is used for space and 

water heating rather than being wasted.

– Small scale: Heat and electricity are only provided for one or 

several nearby buildings

– Other advantages such as providing backup power when the 

grid is not available

Early transition strategy combines above system with 

hydrogen production capability

– Hydrogen can be produced and stored when electricity and 

heat demand are low

– Stored hydrogen can be used later to produce more 

electricity or as vehicle fuel
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Example Molten Carbonate Fuel Cell Tri-Generation System

Fuel Cell Fuel Electricity

Internal 

Reforming

Hydrogen

Heat

MCFC

• Heat from electricity production efficiency losses is used to produce H2

• Heat output is reduced as more hydrogen is produced

• H2 co-production technology is in the prototype stage

• H2 co-production technology could be commercial in next few years
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MCFC Tri-Generation Profile vs. Turn-Down

0

50

100

150

200

250

300

0 50 100 150 200 250 300 350

H2 Production

CHP Output

Net Electricity Output

Electricity Demand (kW)

System Outputs 

Outputs (kW)

• MCFC’s produce more H2 at higher electric power outputs
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H2A Power Model Concept

0

2

4

6

8

10

12

14

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

Electricity Demand (kW)

Heat Demand (kW)

Hydrogen Demand (kW)

0

2

4

6

8

10

12

14

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

Electricity Demand (kW)

Heat Demand (kW)

Hydrogen Demand (kW)

0

2

4

6

8

10

12

14

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

Electricity Demand (kW)

Heat Demand (kW)

Hydrogen Demand (kW)

0

2

4

6

8

10

12

14

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

Electricity Demand (kW)

Heat Demand (kW)

Hydrogen Demand (kW)

peak burner

heat sink

0

2

4

6

8

10

12

14

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

Electricity Demand (kW)

Heat Demand (kW)

Hydrogen Demand (kW)

HOURLY DEMANDS

GRID 

ELECTRICITY 

AND FUEL 

PRICE 

SCHEDULES

HOURLY ENERGY 

FLOWS AND $

• Delivered electricity

• Delivered heat

• Delivered hydrogen

• Fuel used

• Used grid electricity

grid • Sales to grid

• Financial inputs

• Capital cost input

• Replacement costs

• Operating costs

H2A NET PRESENT 

VALUE/CASH FLOW 

ANALYSIS

LEVELIZED COST 

OF ENERGY 

SUPPLIED BY THE 

SYSTEM
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Strategy

Optimally Configure Fuel Cell System with Regard to Building Type 

and Location 

– Molten carbonate fuel cell /hydrogen generation equipment 

installed at the point of use

– Electricity load following

– Hydrogen compression, storage, and dispensing equipment 

included in installation

– Tri-generation system size optimized for the building electrical load

Model energy use, costs, and emissions for fuel cell CHP 

/hydrogen installations for representative building types and 

locations

– Hourly analysis of fuel cell system response to building electricity 

heat, and hydrogen demand

– Full year of analysis (8760 hours)

Use results as input into a life-cycle discounted cash flow economic 

model
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Methodology

H2A Power Model for analysis of energy use, costs, and emissions 

for fuel cell CHP /hydrogen installations for representative 

building types and locations.

Building Information:

– Electricity and heat demand profiles obtained from NREL 

building systems model

• Electricity demand includes air conditioning

• Heat demand includes fuel demand for space and hot water 

heating

Building Types

High School

Hospital

Large Office Building

Large Hotel

Supermarket
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Building Model Climate Zones

Climate 

Zone

Representative City Climate 

Zone

Representative City

1 Miami, FL 4 Baltimore, MD

2 Houston, TX 5 Chicago, IL

3 Los Angeles, CA 6 Helena, MT

Source: DOE Commercial Building Research Benchmarks for Commercial Buildings, Second Draft, June 2008.
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NREL Building Model – Miami Hospital kW of 

Electricity and Heat Demand Each Hour

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Miami Hospital - Winter Demand Profiles

Heat Load Electricity Load

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Miami Hospital - Spring Demand Profiles

Heat Load Electricity Load

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Miami Hospital - Summer Demand Profiles

Heat Load Electricity Load

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Miami Hospital - Fall Demand Profiles

Heat Load Electricity Load
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NREL Building Model – Chicago Hospital kW of 

Electricity and Heat Demand Each Hour
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DRAFT

Demand Profile of Chicago Hospital

0

200

400

600

800

1000

1200

1400

0

103206309411514617720823926

1029113212341337144015431646174918521954

AC Demand MWh Heat Demand MWh

Power Demanded MWh

Building Demand Profiles

Electricity Heat

Maximum = 1160 kW Maximum = 1950 kW

Average = 554 kW Average = 390 kW

Total annual = 4,850 MWh Total annual = 3,440 MWh 

kW demand (binned)
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Optimal Size of the Fuel Cell System as a Function of 

Building Location - Cost of Electricity/Heat/Hydrogen 

For the same type of building (hospitals) in different locations;

The optimal FC size for minimum cost of energy is about the average 

electrical demand + 1/2 standard deviation

Fuel cell sized at;

• Average Electricity 

Load - 0.5 STDev

• Average Electricity 

Load

• Average + 1⁄2 STDev

• Average + 1 STDev

• Average + 1.5 

STDev

Electricity @ 8.2 c/kWh

Natural Gas @ 

$9.79/mmBtu
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Optimal Size of the Fuel Cell System as a Function 

of Building Type - Cost of Energy

For different types of building in the same location;

The optimal FC size for minimum cost of energy is between the average electrical 

demand + 1/2 standard deviation and average demand + 1 standard deviation
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Optimal Size of the Fuel Cell System as a Function 

of Building Type - Cost of Hydrogen

For different types of building in the same location;

The optimal FC size for minimum hydrogen cost is about the average electrical 

demand + 1/2 to 1 standard deviation
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Fuel Cell Response to Electricity Demand Changes

• Winter electricity demand is well below maximum FC output of 

739 kW – FC meets electricity demand

• Winter heat production meets only 13% of heat load

• Fuel cell electrical output follows electricity load

kW
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Fuel Cell Response to Electricity Demand Changes

• Summer electricity demand exceeds maximum FC output of 739 kW

• Summer heat production meets 100% of heat load

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Chicago Hospital - Summer

Heat Load

FC Heat Output

FC Electrical Output

Electricity Load

kW
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Fuel Cell Response to Electricity Demand Changes

• Winter electricity demand is below maximum output of 930 kW

• Winter heat production meets 100% of heat demand

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Miami Hospital - Winter

Heat Load

FC Heat Output

Electricity Load

FC Electrical Output

kW
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Fuel Cell Response to Electricity Demand Changes

• Summer electricity production does not meet peak demand

• Summer heat production meets 100% of heat load

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

0

200

400

600

800

1000

1200

1400

1600

Hour of the Day

Miami Hospital - Summer

Heat Load

FC Heat Output

Electricity Load

FC Electrical Output

kW
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Fuel Cell Utilization and Hydrogen Production for 

Hospitals in Various Climates

Fuel Cell

Size (kW)

Hydrogen

Delivered

(kg/day)

Fuel Cell

Utilization (AC

Output/Max AC

Output)

MIAMI 846 328 81.2%

HOUSTON 799 296 78.0%

LOS ANGELES 640 236 77.4%

HELENA 629 225 75.3%

BALTIMORE 684 244 75.2%

CHICAGO 646 230 74.9%

• Fuel cell sized at average electricity demand + 1⁄2 standard 

deviation

• Higher fuel cell utilization reduces cost
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Fuel Cell Response to Electricity Demand Changes

• For fixed (national average) electricity and natural gas prices, hydrogen cost decreases with 

increasing fuel cell utilization.

• Fuel cell utilization increases for more southern climates because electricity and heat load 

profiles are more uniform between summer and winter
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Electricity and Natural Gas Rates
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Spark Spread – Ratio of Electricity to Natural Gas Price

Commercial

Electricity Rate

(¢/kWh)

Commericial NG

Rates

($/mmBtu)

Spark Spread

(ratio of electricity 

to NG price)

Fairbanks 30.0 4.80 18.3

New York 17.8 10.78 4.8

San Francisco 13.2 10.70 3.6

Los Angeles 12.4 10.15 3.6

Albuquerque 7.7 8.63 2.6

Hartford 11.6 13.12 2.6

Houston 9.0 10.18 2.6

Las Vegas 8.3 9.99 2.4

Boulder 7.7 9.49 2.4

Helena 8.2 10.34 2.3

Baltimore 9.8 12.56 2.3

Phoenix 7.5 9.69 2.3

Seattle 7.3 10.10 2.1

Chicago 7.6 10.78 2.1

Duluth 7.0 9.94 2.1

Miami 8.3 12.29 2.0

Minneapolis 6.6 10.15 1.9

Atlanta 7.5 12.21 1.8
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Spark Spread Effect on Hydrogen Cost
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Conclusions

Climate influences the cost of energy produced by fuel 

cell tri-generation systems because of it’s effect on 

fuel cell utilization

The ratio of electricity to natural gas price influences the 

cost of hydrogen from a tri-generation system 

because of two factors

– If electricity prices are high, electricity produced by the fuel 

cell can be “priced” higher, thus reducing the cost of 

hydrogen

– If natural gas prices are low, the fuel cell tri-generation 

system produces electricity, heat, and hydrogen for a lower 

cost.
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Questions ?