A national laboratory of the U.S. Department of Energy

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Innovation for Our Energy Future 

A System-of-Systems Framework 

for the Future Hydrogen-Based 

Transportation Economy 

Preprint 

Michael Duffy and Debra Sandor 

To be presented at the 2008 INCOSE International Symposium 

The Netherlands 

June 15–19, 2008 

Conference Paper 

NREL/CP-150-42989 

June 2008 

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A System-of-Systems Framework for the Future 

Hydrogen-Based Transportation Economy 

Michael Duffy, PhD 

National Renewable Energy Laboratory 

1617 Cole Boulevard, MS-1722 

Golden, CO 80401-3393 

303-275-3022 

michael_duffy@nrel.gov 

Debra Sandor, PMP 

National Renewable Energy Laboratory 

1617 Cole Boulevard, MS-1722 

Golden, CO 80401-3393 

303-275-3029 

debra_sandor@nrel.gov 

Copyright © 2008 by Midwest Research Institute. All Rights Reserved. This work is subject to Government rights. Used by INCOSE with 

permission for the 2008 INCOSE International Symposium, International Council on Systems Engineering. 

Abstract. Today, almost 60% of the petroleum consumed in the United States is imported. The 

nation’s current transportation system of systems (SoS) relies almost exclusively on refined 

petroleum products, accounting for over two-thirds of the oil used in the U.S each day. As a 

nation, we must work to reduce our dependence on foreign sources of oil in a manner that is 

affordable, ensures national energy security and preserves environmental quality. In the longterm, a potential solution to the nation’s transportation energy problems is an operational 

hydrogen-based transportation economy. Transitioning to any alternative transportation fuel on a 

national scale will require the creation of a robust and cost-effective system of systems that 

operates in concert with the dynamics of today’s mature and highly-networked transportation 

infrastructure. Using a supply chain point-of-view to trace the flow of transportation fuels 

through the necessary SoS, this paper addresses the current petroleum-based economy for 

transportation, the U.S. Department of Energy’s (DOE’s) vision for a future hydrogen-based 

transportation economy and the significant challenges associated with such a massive market and 

infrastructure transformation. 

Introduction 

Ready access to affordable oil is the cornerstone of the U.S. economy. In 2004, the U.S. 

consumed almost 21 million barrels of crude oil and refined products per day [AEO, 2006]. 

Approximately 60 percent of the U.S. demand was supplied by imports.[AEO, 2006] The 

transportation sector, which receives nearly all of its energy from petroleum products, accounts 

for two-thirds of U.S. petroleum use. As President Bush aptly noted in his 2006 State of the 

Union Address, “America is addicted to oil.”; but U.S. demand continues to grow, with 

petroleum imports expected to top 26 million barrels per day by 2025. [AEO, 2006] In light of 

increasing worldwide oil demand, our increased reliance on imported sources of energy threatens 

our national security, economy and future competitiveness. 

How this growing demand for energy is met poses one of the most complex and challenging 

systems engineering problems of our time. The current national energy dialogue reflects the 

challenge in simultaneously considering the social, political, economic, and environmental issues 

as the future desired transportation SoS is defined, necessary interim technological capabilities 

are established, and programs and investments are implemented to meet those capabilities. 

1 
U.S. Government Goals 

In 2003, President Bush announced the Hydrogen Fuel Initiative to reverse America's 

growing dependence on foreign oil by developing the technology needed for commerciallyviable, hydrogen-powered fuel cells—a way to power cars, trucks, homes, and businesses that 

produces no pollution and no greenhouse gases. Through partnerships with the private sector, the 

President's Hydrogen Fuel Initiative seeks to develop hydrogen, fuel cell, and infrastructure 

technologies needed to make it practical and cost-effective for large numbers of Americans to 

choose to use fuel cell vehicles by 2020 (Whitehouse 2003). 

In 2006, the President unveiled the Advanced Energy Initiative, which outlined significant 

new investments and policies to (1) accelerate deployment of efficient hybrid and clean diesel 

vehicles in the near-term, (2) develop domestic renewable alternatives to gasoline and diesel 

fuels in the mid-term, and (3) invest in the advanced battery and hydrogen fuel-cell technologies 

needed for substantial reductions in future oil demand. Together, these efforts will help the U.S. 

reach the President’s long-term goal of replacing more than 75 percent of our oil imports from 

the Middle East by 2025 (Bush 2006). 

Transitioning from our current petroleum-based transportation fuel economy to a future 

hydrogen-based transportation fuel economy that incorporates significant amounts of renewable 

energy can be characterized and addressed as a classical SoS problem. This paper provides a 

working definition of SoS used to frame the discussion; describes the current petroleum-based 

transportation SoS; presents the DOE’s vision for a future hydrogen-based transportation SoS, 

and describes the systems engineering approach that is being used to bring this long-term vision 

into being. 

System of Systems Overview 

While SoS has its roots in the established systems engineering discipline, as outlined in 

Table 1, addressing SoS goes beyond traditional systems engineering in a number of ways. 

 System Engineering

Perspective

System of Systems 

Engineering Perspective

Scope Product/Product Enterprise/Capability 

Autonomous/Well-bounded Interdependent 

Objective Enable fulfillment of 

requirements 

Enable evolving capability 

Structured project process Guide integrated portfolio 

Time Frame System lifecycle Multiple, interacting 

system lifecycles 

Discrete beginning and end Amorphous beginning 

Important history and 

precursors 

Organization Unified and authoritative Collaborative network 

Development Design follows 

requirements 

Design is likely legacyconstrained 

Verification System in network context Ensemble as a whole 

One time, final event Continuous, iterative 

Table 1. Differences Between Traditional Systems Engineering and System of Systems 

Engineering [SOSECE, 2007] 

2 
The field of SoS engineering is still emerging and the SoS community has not yet come to 

agreement upon a single commonly-accepted definition of SoS. As a starting point, the 

International Council on Systems Engineering (INCOSE) defines SoS as follows: 

“System of systems applies to a system of interest whose system elements are 

themselves systems; typically these entail large-scale inter-disciplinary problems 

with multiple, heterogeneous, distributed systems.” [INCOSE, 2006] 

A key aspect of SoS that is not called out in this definition is the importance of context in 

developing a desired physical capability. According to the System of Systems Center of 

Excellence, “SoS engineering addresses a complex system in terms of relationships, politics, 

operations, logistics, stakeholders, patterns, policies, training and doctrine, context, environment, 

conceptual frame, geography and boundaries.” [SOSECE, 2007] This broader definition is 

needed to characterize and transform the petroleum-based transportation SoS. 

Petroleum-Based Transportation System of Systems 

Conceptually, the petroleum-based transportation SoS can be represented as shown in Figure 1 

and described in terms of capability and context. 

Political Economic Environmental Social 

Context: Operational Environment 

Fuels 

End Use 

FeedstockTo-Fuel 

Conversion 

Fuels

Distribution 

Capability: Systems and Stakeholders 

Feedstock 

Production 

Feedstock 

Logistics 

Figure 1. Transportation Fuel System of Systems 

Capability: The physical systems and infrastructure included in the transportation SoS can be 

organized around five interdependent systems that comprise the feedstock-to-fuel supply chain. 

The primary objective of each system is described in the context of the existing transportation 

SoS, which moves crude oil from its source to the final processed fuel used by consumers, as 

illustrated in Figure 2. 

3 
Refineries 

Platform 

Production 

Wellhead 

Production 

Retail Outlets 

Gasoline 

Distribution 

Bulk Terminal 

Storage 

Tanker 

Truck 

Barge 

Fuel End 

Use 

Fuel 

Distribution 

Crude Oil 

Refining 

Crude Oil 

Logistics 

Crude Oil 

Production 

Pipeline 

Figure 2. The Existing Petroleum-Based Transportation SoS 

• Feedstock Production System. The objective of the feedstock production system is to 

produce large quantities of high-quality raw feedstock cost-effectively, efficiently and in 

compliance with applicable safety, environmental, etc. regulations. In the case of the 

current petroleum-based transportation SoS, this is all of the exploration and production 

infrastructure (e.g., drilling rigs, production platforms) required to extract crude oil from 

reserves around the globe. 

• Feedstock Logistics System. The objective of the feedstock logistics system is to collect, 

store and transport raw feedstock from the production point to the fuel production 

facility. In the case of the current petroleum-based system, this includes all of the 

infrastructure required to move crude oil from the field to the refinery. The nation’s 

extensive network of petroleum transmission pipelines are the primary means of moving 

crude oil from oil fields on land and offshore to refineries where the oil is turned into 

fuels and other products. There are approximately 55,000 miles of crude oil trunk lines in 

the U.S. that connect regional markets.[Pipeline 101, 2007a] The crude oil logistics 

system also includes ports, storage tanks, barges and tankers depending on where the oil 

supply originates. 

• Feedstock-to-Fuel Conversion System. The objective of the feedstock-to-fuel 

conversion system is to process raw feedstock into specification-compliant transportation 

fuel. In the case of the current petroleum-based system, this includes all of the 

infrastructure (e.g., reactors, distillation columns, etc.) required to operate a refinery. U.S. 

refining capacity stands at approximately 17 million barrels per day.[Petroleum Annual 

Supply, 2004] Refineries process the crude oil feedstock into gasoline, diesel fuel, 

heating oil, jet fuel, liquefied petroleum gases and other petroleum-based products. 

Gasoline, which represents nearly 45 percent of the domestic production of all refined 

products, is the petroleum product most demanded by U.S. consumers.[EIA, 2005]

• Fuels Distribution System. The objective of the fuels distribution system is to move 

transportation fuel from the refinery to the consumer point-of-use (i.e., the consumer’s 

4 
vehicle). In the case of the current petroleum-based system, this includes all of the 

infrastructure (e.g., pipelines, storage tanks, fuel dispensers) required to transport, store 

and dispense transportation fuel. There are approximately 95,000 miles nationwide of 

refined products pipelines, which move gasoline, diesel fuel and other petroleum 

products to consumer markets.[API, 2006]. The majority of gasoline is shipped by 

pipeline to bulk storage terminals near consuming areas. At these terminals the gasoline 

is loaded into tanker trucks and then delivered to one of the approximately 167,000 retail 

outlets in the U.S., where the gasoline is unloaded into the underground tanks at the gas 

station.[EIA, 2005] 

• Fuels End Use System (Vehicle). The objective of the fuels end-use system is to provide 

high-performance, reliable, affordable and safe vehicles to consumers. In the case of the 

current petroleum-based transportation fuel system, this is all of the infrastructure (e.g., 

auto industry and supporting industries – rubber, computer chips, steel etc.) required to 

manufacture and distribute vehicles to consumers. In 2005, 12 million cars and 

commercial vehicles were produced in the U.S. [DOT, 2006a] In 2005, there were almost 

250 million highway vehicles registered in the U.S. [DOT, 2006b] 

Context: The transportation SoS must operate within the context of political, economic, social 

and environmental conditions that influence its physical domain. Together, these perspectives 

serve to define “the interrelated conditions which exemplify a system’s state of being and 

which describe its purpose, scope, and meaning for services it may offer.”[Polzer, et al., 2007] 

A brief description of each perspective with respect to the transportation SoS follows. 

• Political Context. Government policies, incentives, laws and regulations have affected 

the transportation SoS for many decades. Global politics are, and will continue to be, a 

key consideration in the political operating environment, driven by the fact that over twothirds of the world’s remaining global oil reserves lie in the Middle East.[Rifkin, 2002]

Significant government incentives that directly support the U.S. petroleum based industry 

have been in place for years. For example, between 1968 and 2000, the petroleum 

industry received over $150 billion dollars in tax breaks – for exploring for and 

producing petroleum within the U.S. through percentage depletion deductions, expensing 

of exploration and development costs and production of non-conventional fuels.[GAO, 

2000] Since the 1970s, laws and regulations related to the transportation SoS have been 

primarily driven by increasing concerns for the environment, safety and energy efficiency 

(e.g., mandated vehicle emissions requirements and fleet average fuel economy 

standards).

• Economic Context. The transportation fuel SoS operates within a global marketplace. 

“Oil is the world economy’s most important source of energy and is, therefore, critical to 

economic growth.” With an estimated total value of between $2 trillion and $5 trillion, 

the petrochemical industry is the largest business in the world.[Rifkin, 2002] The 

automobile industry is also a major contributor to global and U.S. economies. In 2005, 

the total sales of automobiles were about 4% of the nation’s gross domestic product, 

equivalent to around $500 billion dollars in sales. It is estimated that for every 

autoworker 7.5 jobs are created in other industries.[Ford Motor Company, 2007] On the 

down side, U.S. reliance on imported oil has significant negative impacts on the U.S. 

economy. The last three major oil price shocks, which were driven by political events in 

the Middle East, pushed the U.S. economy into economic recession. In addition, the U.S. 

5 
spends an estimated $200,000 per minute on foreign oil, accounting for about one-fourth 

of the annual trade deficit. [UCS, 2002] In the future, petroleum prices are expected to 

rise as worldwide oil demand continues to increase and oil supplies begin to wane, 

further increasing cash flow out of the U.S. economy. 

• Environmental Context. The current petroleum-based transportation SoS has had 

significant negative impacts on the environment. “Oil extraction, refining and 

transportation are responsible for land destruction and toxic contamination at the 

extraction point, oil spills in oceans around the world, and toxic air and water emissions 

from oil refining operations.”[CWAC, 2007] Millions of acres of farmland and wildlife 

habitat have been lost to roads and highways across the U.S. and vehicle emissions are 

major contributors to air and water pollution, as well as global climate change. Today, the 

transportation sector accounts for about a third of total U.S. emissions of carbon dioxide 

(an important greenhouse gas).[DOE Biomass Program, 2007] Not surprisingly, the 

transportation fuel SoS operates under a multitude of environmental protection laws and 

regulations regarding oil production, transport, and use. Pressure from environmental 

advocacy groups continues to motivate government action to mitigate and minimize the 

environmental impacts of our current transportation SoS through sustainable, energyefficient and clean alternatives. 

• Social Context. Affordable transportation fuel and personal mobility are virtual “rights” 

in the U.S. today. Even as traffic congestion and air pollution plague our cities, oil and 

the automobile are the foundation of our 21st century commercial and social lives. Today, 

the average American consumes about 25 barrels of oil per year; for perspective, the 

average person in China uses less than 2 barrels of oil per year.[Nationmaster, 2007] 

Modern food production and distribution are almost exclusively dependent on oil and 

natural gas – from producing the fertilizer used to grow crops to fueling harvesting 

equipment and refrigerated trucks that deliver food to consumers – and today, agriculture 

is one of the world’s most energy-intensive industries. .[Worldwatch Institute, 2007] 

Recognition that this oil-dependent lifestyle cannot be sustained into the future is slowly 

building – driven in part by the pinch consumers feel as the costs of food, gasoline and 

consumer products rise in response to higher oil prices, as well as increasing concern for 

the environment. For example, since 2004, the popularity of sport utility vehicles (SUVs) 

has waned and consumer demand for more fuel efficient vehicles has risen.[Worldwatch 

Institute, 2007] Nonetheless, consumers maintain their high expectations regarding 

performance, comfort, safety, reliability, cost, and size of the vehicles they purchase and 

drive. This illustrates the primary challenge from a social perspective – overcoming our 

natural resistance to change and managing expectations as alternative transportation fuels 

enter the market. 

Vision for a Future Hydrogen Economy 

Hydrogen is the most abundant element in the universe but hydrogen does not exist alone in 

nature; it must be isolated from hydrogen-containing substances or feedstocks--water (H20), 

natural gas (CH4), biomass (cellulose, hemicellulose or lignin), and hydrocarbons like coal. The 

U.S. has enough domestic energy resources—from wind, solar, biomass, hydroelectric, coal and 

nuclear---to meet all of the energy needs of the entire country, not just the transportation needs. 

6 
In DOE’s 2040 vision of an operational hydrogen-based transportation economy, a robust 

hydrogen-based energy industry and supporting infrastructure will be in place, fully operational 

and capable of producing 64 million metric tons of hydrogen (quantity needed to fuel 300 

million fuel cell vehicles annually). This vision, in terms of the elements of a hydrogen energy 

infrastructure illustrated in Figure 3, is outlined here. 

Operational Environment

Political Economic Environmental Social

Feedstocks

• Natural gas

• Coal

• Biomass

• Water

Hydrogen-Based Transportation SoS

H2 Production

• Steam reforming

• Electrolysis

H2 Delivery

• Pipeline

• Rail/Truck

H2 Storage

• Liquid 

• Compressed gas

H2 Conversion

• ICE

• Fuel Cells

Vehicles

• Light duty

• Trucks

Feedstocks

• Natural gas

• Coal

• Biomass

• Water

Hydrogen-Based Transportation SoS

H2 Production

• Steam reforming

• Electrolysis

H2 Production

• Steam reforming

• Electrolysis

H2 Delivery

• Pipeline

• Rail/Truck

H2 Delivery

• Pipeline

• Rail/Truck

H2 Storage

• Liquid 

• Compressed gas

H2 Storage

• Liquid 

• Compressed gas

H2 Conversion

• ICE

• Fuel Cells

H2 Conversion

• ICE

• Fuel Cells

Vehicles

• Light duty

• Trucks

Operational Environment

Political Economic Environmental Social

Feedstocks

• Natural gas

• Coal

• Biomass

• Water

Hydrogen-Based Transportation SoS

H2 Production

• Steam reforming

• Electrolysis

H2 Delivery

• Pipeline

• Rail/Truck

H2 Storage

• Liquid 

• Compressed gas

H2 Conversion

• ICE

• Fuel Cells

Vehicles

• Light duty

• Trucks

Feedstocks

• Natural gas

• Coal

• Biomass

• Water

Hydrogen-Based Transportation SoS

H2 Production

• Steam reforming

• Electrolysis

H2 Production

• Steam reforming

• Electrolysis

H2 Delivery

• Pipeline

• Rail/Truck

H2 Delivery

• Pipeline

• Rail/Truck

H2 Storage

• Liquid 

• Compressed gas

H2 Storage

• Liquid 

• Compressed gas

H2 Conversion

• ICE

• Fuel Cells

H2 Conversion

• ICE

• Fuel Cells

Vehicles

• Light duty

• Trucks

Figure 3: Elements of a Hydrogen Fuel Infrastructure 

Hydrogen Production. In 2040, a variety of domestic feedstocks will be available for hydrogen 

production including biomass; coal (with carbon sequestration); and electricity-generating 

renewables such as wind and solar power as well as nuclear power (to drive water electrolysis). 

Feedstock selection will be based on the resources and processes that are most economical or 

specifically selected by particular states or regions. Hydrogen will be produced in centralized 

facilities in remote locations, in power parks and fueling stations in our communities, in 

distributed facilities in rural areas, and at customers’ homes and businesses, using a variety of 

hydrogen production processes, as outlined in Figure 4. Thermal and electrochemical processes 

will use fossil fuels, biomass, or water as feedstocks and release little or no carbon dioxide into 

the atmosphere; water-splitting microorganisms and biomass fermentation will also become 

viable sources for renewable hydrogen. (Hydrogen Posture Plan 2006) 

7 
Steam Methane Reforming

Water Electrolysis

Energy 

Source

Hydrogen Production 

Options

Gasification/Pyrolysis

Water Electrolysis

Water Electrolysis

Photoelectrochemical

Photobiological

Natural Gas

Coal

Solar

Biomass

Nuclear Water Electrolysis

Thermochemical Water Splitting

Wind Water Electrolysis

Gasification/Pyrolysis

Fermentation/Anaerobic Digestion

Water Electrolysis

Figure 4: Hydrogen Production Options 

Hydrogen Delivery. In 2040, a national supply network will evolve from the existing fossil 

fuel-based infrastructure to accommodate distribution of 64 million metric tons of hydrogen 

produced in both centralized and decentralized production facilities. Pipelines will distribute 

hydrogen to high-demand areas, and trucks and rail will distribute hydrogen to rural and lower 

demand areas. 

Hydrogen Storage. In 2040, the hydrogen storage problem will be solved with lightweight, 

low-cost, and compact storage devices. One specific solution will be the use of high-tech solid 

materials, like metal hydrides and carbon nanotubes. These materials, along with chemical 

storage, may provide safe high-density storage options for both stationary and mobile 

applications. 

Hydrogen Conversion and End Use Applications. In 2040, fuel cells will be a mature, costcompetitive technology in commercial production. Advanced, hydrogen powered energy 

generation devices such as combustion turbines and reciprocating engines will enjoy widespread 

commercial use. Hydrogen will become the dominant fuel for vehicle fleets across the country 

(target of 300 million fuel cell vehicles on the road in 2040). 

8 
Evolution to a Hydrogen-Based Transportation Fuel SoS 

Where Are We Now? Existing Hydrogen Industry 

Outside the space industry, hydrogen is not used as a fuel today except for a few automotive 

demonstration vehicles. Most hydrogen is used to convert heavy petroleum sources into lighter 

fractions suitable for use as fuels and to produce ammonia for fertilizer production. The existing 

hydrogen supply chain for these chemical applications is mature, but not sufficient to support 

significant transportation applications. 

Hydrogen Production. Today, the primary feedstock for hydrogen production is natural gas. 

Coal is also used as a hydrogen feedstock, and ethane, propane, butane and naphtha are also 

occasionally used as feedstocks for hydrogen production in refineries. Grid electricity, produced 

primarily from coal and natural gas, in combination with water, is also used as hydrogen 

feedstock. Approximately 9 million tons of hydrogen are produced annually for the industrial 

sector, largely by steam methane reforming of natural gas as the hydrogen feedstock. To a lesser 

degree, hydrogen is produced via electrolysis by passing electricity through two electrodes in 

water. The water molecule is split and produces oxygen at the anode and hydrogen at the 

cathode. Electrolyzers are used primarily to produce small volumes of relatively high-purity 

hydrogen and oxygen for specialized applications. 

Hydrogen Delivery. Today, the largest volumes of gaseous hydrogen are delivered by pipeline. 

The most extensive pipeline networks are located in the Gulf Coast, where large quantities of 

hydrogen are consumed at refineries located in the region. (Hydrogen CEH 2004) Hydrogen is 

also transported over the road in compressed hydrogen cylinders and cryogenic liquid tankers. 

Today, there are 70 hydrogen refueling stations in operation in the U.S. and Canada; of these, 15 

are publicly accessible. 

Hydrogen Storage. Hydrogen gas is difficult to store and transport because it is very light. To 

make it easier to handle, the energy density of hydrogen gas is increased in one of two ways. 

Hydrogen gas can be compressed to a high pressure (up to 7,000 psi) or cooled to a very low 

temperature (below -423 F) so that the hydrogen gas becomes a liquid. In either case, the 

hydrogen is stored in specially designed tanks. 

Hydrogen Conversion and End Use Applications. Today hydrogen is primarily used as a 

chemical, rather than a fuel. It is used to make cleaner gasoline, fertilizer, and food products. 

Hydrogen’s primary use as a fuel is in the U.S. Space Program for both the main engine of the 

Space Shuttle and the fuel cells that provide the Shuttle’s electric power. In the race for the 

potential fuel cell vehicle market, GM is dispatching100 fuel cell Chevy Equinox crossovers to 

drivers in New York, Los Angeles and Washington, D.C.; Ford has a handful of fuel cell Ford 

Focus vehicles being tested throughout the world; DaimlerChrysler has more than 100 fuel cell 

vehicles on the road, including 60 passenger cars and 30 buses; Toyota is testing 20 fuel cell 

Highlanders; and Honda recently unveiled its next-generation fuel cell vehicle, the FCX. 

(Detroit News 2007) 

How Do We Get There? Transition to a Hydrogen Future 

Dramatic advancements in the performance and cost-effectiveness of hydrogen and fuel cell 

technologies are necessary before they will be competitive with today’s petroleum-based 

transportation infrastructure. In addition, transitioning to a hydrogen SoS will require initially 

9 
integrating with and ultimately transforming industries of the current transportation SoS, as well 

as the established chemical-based hydrogen production industry, the natural gas industry, and 

utilities that provide electricity for the grid. A phased approach will allow new energy systems to 

be integrated into the existing energy infrastructure as technologies and systems advance to the 

point of commercial readiness. The transition to a hydrogen-based transportation SoS will occur 

incrementally over many decades as technologies advance, market acceptance increases and 

large investments in infrastructure that can support the expanded production, delivery, storage 

and use of hydrogen are made. An overview of the step-wise transition is presented in Figure 5. 

Figure 5: Overview of the Transition to a Hydrogen Economy (Hydrogen Posture Plan 2006) 

The transition to a hydrogen-based transportation SoS is envisioned to occur in two phases. 

Near- to Mid-Term (2007-2020). The first steps toward a clean hydrogen future will build on 

the commercial processes and systems in use today. To build initial hydrogen fuel demand, 

hydrogen production capacity via steam reforming natural gas and water electrolysis using 

conventional electricity-generating sources (coal and natural gas) will be expanded. Distributed 

hydrogen generation will begin to play a role. Existing hydrogen distribution systems will be 

expanded dramatically. Fleets will transition to hydrogen fuel vehicles and the first hydrogen 

fuel cell vehicles will be introduced to consumer markets. Government-supported R&D will 

advance hydrogen production, storage and end-use technologies, and improve system 

performance and economics. Government policies and financial incentives will be implemented 

10 
to stimulate industry investment and encourage consumer adoption of hydrogen technologies and 

systems. 

Mid- to Long-Term (Beyond 2020). As hydrogen markets grow, costs across the hydrogen 

transportation fuel supply chain will decrease through economies of scale and dramatic 

technological advances. Natural gas and coal will be replaced by biomass and water as primary 

hydrogen feedstocks. Distributed hydrogen generation capability will expand significantly to 

enable hydrogen to be used where it is produced. Hydrogen distribution systems will also be 

expanded to all regions of the U.S. as hydrogen-fueled vehicles become widely available to 

consumers. Government-supported R&D will continue to advance hydrogen production, storage 

and end-use technologies for next-generation applications. In this timeframe, government 

financial support for commercial ventures and consumer acceptance will no longer be needed as 

the hydrogen-based transportation SoS becomes firmly established. 

Using Model-Based System Engineering to Bring the Future 

Hydrogen-Based Transportation Economy into Being 

The SoS challenge is how to design and implement a smooth transition from the legacy 

petroleum-based transportation SoS to a future hydrogen-based transportation SoS. 

DOE is using a model-based systems engineering (MBSE) approach to document and track 

the progression from the existing “legacy” transportation SoS to a future hydrogen-based SoS. 

MBSE is a methodology for developing and analyzing system requirements using graphical 

representations of the underlying functions, requirements, architecture, relationships and 

interfaces that define the system. The MBSE approach helps to improve understanding and 

communication of complex system and system-of-systems designs. Beginning with the end in 

mind, i.e., the vision of a future hydrogen economy, MSBE can help to define and document 

what it will take, in terms of capability, to get from here to there. 

The system engineering fundamentals underlying the MBSE approach can be readily 

expanded to SoS applications. Specifically, the capabilities required for a future hydrogen-based 

SoS can be defined and managed in terms of the functions, requirements, architecture and tests 

(FRAT) framework (Mar and Morais, 2002) as follows: 

1. Describe each system within the SoS in terms of four views: 

• What the system does (functions) 

• How well the system performs its functions (requirements) 

• What the system actually is (architecture) 

• Verification and validation activities that provide the proof that the actual system 

satisfies the intended functions and requirements (test) 

2. Define and understand the three interacting systems: 

• Physical system: the required infrastructure for an operational hydrogen economy 

• Program system: the RD&D program that brings the desired infrastructure into being 

• External system: everything else that interacts with the physical and program systems 

The desired SoS infrastructure and the RD&D program for establishing the desired 

infrastructure are derived from the vision and mission, and captured in an integrated baseline, as 

illustrated in Figure 6. The purpose of the integrated baseline is to establish and control the 

documented, traceable relationships between requirements, functions, strategies, technologies, 

etc. of the SoS and the program for bringing it into being. The integrated baseline is comprised 

11 
of two components. The technical baseline, which focuses on defining the technological 

capabilities in terms of configuration, performance and characteristics of the SoS, ensures that 

we will be doing the right things. The technical baseline defines where the program is at any 

point in time and where it ultimately must be (from a technology development standpoint). The 

programmatic baseline, which focuses on the scope of work, schedule and costs of activities 

required to bring the technological capabilities into being, ensures that we will do things right. 

The goal is an integrated baseline for a requirements-driven, mission-oriented program and, 

hence, a firm foundation for designing and implementing the SoS necessary to transition to an 

operational hydrogen economy. 

Schedule

0

2000000

4000000

6000000

8000000

10000000

12000000

14000000

16000000

18000000

20000000

1 s t Q tr 2 n d Q tr 3 rd Q tr 4 th Q tr

A c tu a l

P la n

Budget

Programmatic Baseline

Figure 6: A Requirements-Driven, Mission-Oriented Transition Program 

The hydrogen integrated baseline is built on the CORE MBSE software platform (Vitech 

Corporation 2007), a database-driven integrated systems engineering and program management 

support tool, designed to document and manage each step of the FRAT process in a centralized 

electronic repository. In addition to providing a graphical representation of the system, CORE 

allows program organization and efforts to be viewed from a variety of perspectives through 

automatic generation of standard reports, tables, and diagrams. Figure 7 illustrates how CORE 

can be used to organize, coordinate and document both the technical and programmatic baselines 

necessary to efficiently achieve the desired operational hydrogen economy. This diagram 

highlights the traceability of the information back to its source document and shows the key 

relationships between the model components (or “elements”). 

(the process that establishes the technological capability)

Schedule

0

2000000

4000000

6000000

8000000

10000000

12000000

14000000

16000000

18000000

20000000

1 s t Q tr 2 n d Q tr 3 rd Q tr 4 th Q tr

A c tu a l

P la n

Budget 0

2000000

4000000

6000000

8000000

10000000

12000000

14000000

16000000

18000000

20000000

1 s t Q tr 2 n d Q tr 3 rd Q tr 4 th Q tr

A c tu a l

P la n

Budget

Programmatic Baseline

(the process that establishes the technological capability)

Production Conversion

Storage

Delivery

Applications

Hydrogen Technological

Capabilities (2015)

Technical Baseline

(the desired technological capability)

TWRS

1.1.1

WASTE

STORAGE

1.1.1.2

MGMT SYSTEMS

1.1.1.1

WASTE

DISPOSAL

1.1.1.3

WASTE

CHARACTER.

1.1.1.2.2

TANK FARM

OPERATIONS

1.1.1.2.1

TANK FARM

OPERATIONS

1.1.1.2.1

TANK FARM

OPERATIONS

1.1.1.2.1

1.1.1.2.1.1

1.1.1.2.1.2

WBS

Requirements

Progress

TWRS

1.1.1

WASTE

STORAGE

1.1.1.2

MGMT SYSTEMS

1.1.1.1

WASTE

DISPOSAL

1.1.1.3

WASTE

CHARACTER.

1.1.1.2.2

TANK FARM

OPERATIONS

1.1.1.2.1

TANK FARM

OPERATIONS

1.1.1.2.1

TANK FARM

OPERATIONS

1.1.1.2.1

1.1.1.2.1.1

1.1.1.2.1.2

WBS

TWRS

1.1.1

WASTE

STORAGE

1.1.1.2

MGMT SYSTEMS

1.1.1.1

WASTE

DISPOSAL

1.1.1.3

WASTE

CHARACTER.

1.1.1.2.2

TANK FARM

OPERATIONS

1.1.1.2.1

TANK FARM

OPERATIONS

1.1.1.2.1

TANK FARM

OPERATIONS

1.1.1.2.1

1.1.1.2.1.1

1.1.1.2.1.2

WBS

Requirements

Progress

Production Conversion

Storage

Delivery

Applications

Hydrogen Economy Mission

(2040 2020) (the desired 2040 hydrogen economy)

Vision

12 
necessary and sufficient

Goal

Functions

(decomposed by)

basis of

Barriers (Risks)

• Normal text represents elements

• Italic text represents relationships

assigned to

Organizations

Programs/Projects

(includes) resolved by

Program A

Project a Project b Project c

Requirements

(refined by)

Documents 

documents

Objective 1

Target 1 Target 2 Target 3

resolved by

Technical Tasks

(decomposed by)

Products

• Outputs

output from/

input to

Milestones

Go-No Go Decisions

Downselects

achieves

Task 1

Subtask i Subtask j Subtask k

Technical

Baseline

Programmatic

Baseline

necessary and sufficient

Goal

Functions

(decomposed by)

basis of

necessary and sufficient

Goal

Functions

(decomposed by)

basis of

Barriers (Risks)

• Normal text represents elements

• Italic text represents relationships

assigned to

Organizations

Programs/Projects

(includes) resolved by

Program A

Project a Project b Project c

assigned to

Organizations

Programs/Projects

(includes) resolved by

Program A

Project a Project b Project c

Requirements

(refined by)

Documents 

documents

Objective 1

Target 1 Target 2 Target 3

Requirements

(refined by)

Documents 

documents

Objective 1

Target 1 Target 2 Target 3

resolved by

Technical Tasks

(decomposed by)

Products

• Outputs

output from/

input to

Milestones

Go-No Go Decisions

Downselects

achieves

Task 1

Subtask i Subtask j Subtask k

resolved by

Technical Tasks

(decomposed by)

Products

• Outputs

output from/

input to

Milestones

Go-No Go Decisions

Downselects

achieves

Task 1

Subtask i Subtask j Subtask k

Technical

Baseline

Programmatic

Baseline

Figure 7: Implementing the SoS Engineering Process within CORE 

The technical information for the baseline – requirements (in the form of performance and 

cost targets), barriers (risks), and technical tasks and milestones – is drawn from high-level 

guiding documents for the DOE Hydrogen Program (DOE Strategic Plans, DOE Hydrogen 

Program Posture Plan and Multi-Year Program Plans; available at 

http://www.hydrogen.energy.gov/). The programmatic information for the baseline – integrated 

portfolio of projects (which form the basis of the Program’s work breakdown structure), along 

with the associated budgets, schedules and resource requirements – is developed in conjunction 

with the DOE Hydrogen Program and Project management teams. The integrated baseline is 

updated regularly as technologies advance, requirements evolve, and budgets expand and 

contract. 

The integrated baseline as implemented in the CORE MBSE software provides a robust tool 

to (1) document and track the current state and progress of the hydrogen SoS and (2) establish a 

defensible basis for budget estimates and technical decisions as the hydrogen fuel SoS moves 

from concept to commercial reality. 

Summary/Conclusions 

Deploying significant volumes of hydrogen fuel will require major technology advancements 

along with consistent government policies to spur the transformation of the current petroleumbased market and infrastructure. Efforts to change energy infrastructure will require sustained 

public and private sector commitment and investment over a multi-decade period. A system-ofsystems framework can effectively guide the complex evolutionary process, in which advanced 

transportation fuels and systems will be continually integrated into the existing petroleum-based 

transportation infrastructure as they become commercially available. 

13 
References 

Annual Energy Outlook 2006 (AEO 2006a). U.S. Energy Information Adminstration. 

http://www.eia.doe.gov/oiaf/archive/aeo06/gas.html

AEO 2007 http://www.eia.doe.gov/oiaf/aeo/overview.html 

(API 2006) http://www.api.org/aboutoilgas/sectors/pipeline/index.cfm 

Bush, George W. State of the Union Address, January 31, 2006. 

http://www.whitehouse.gov/stateoftheunion/2006/

(Detroit News 2007) GM Aims to Market Fuel Cell Vehicles. Detroit News Website (visited 10-

02-07). The Detroit News. June 15, 2007. 

http://www.detnews.com/apps/pbcs.dll/article?AID=/20070615/AUTO01/706150354/1001/b

iz 

(DOE Alternative Fueling Station Locator 2007) DOE Alternative Fueling Station Locator. DOE 

Alternative Fuels Data Center Website (visited 10-17-07). 

http://afdcmap2.nrel.gov/locator/findpane.asp 

Fuel Cell Basics: Applications. Fuel Cells 2000 Website (visited 10-28-07) 

http://www.fuelcells.org/basics/apps.html 

(Hydrogen CEH 2004) CEH Marketing Research Report: Hydrogen. August 2004. Chemical 

Economics Handbook. SRI Consusulting. 

(Hydrogen Posture Plan 2006) Hydrogen Posture Plan: An Integrated Research, Development 

and Demonstration Plan. (December 2006). U.S. Department of Energy and U.S. Department 

of Transportation. http://www.hydrogen.energy.gov/pdfs/hydrogen_posture_plan_dec06.pdf

Mar, Brian W. and Bernard G. Morais. FRAT-A Basic Framework for Systems Engineering. 

INCOSE 2002 International Symposium, July 28-August 1, 2002. Las Vegas, Nevada. 

http://www.eskimo.com/~jjs-sbw/524_bmar.PDF 

LLNL https://eed.llnl.gov/flow/pdf/USEnFlow02-quads.pdf 

(National Hydrogen Association 2007) Hydrogen Fueling Stations. National Hydrogen 

Association website. (visited 10/3/07). 

http://www.hydrogenassociation.org/general/fuelingSearch.asp 

Rifkin, Jeremy. The Hydrogen Economy. Penguin Group (USA) Inc. 2002. p.121-122. 

(Union of Concerned Scientists 2002) Energy Security: Solutions to Protect America’s Power 

Supply and Reduce America’s Oil Dependence. (January 2002). Union of Concerned 

Scientists. www.ucsusa.org

U.S. Energy Information Administration, Petroleum Supply Annual 2004, Vol. I, Tables 36 and 

40. (EIA 2004a) 

U.S. Energy Information Administration, Where Does My Gasoline Come From?, June 2005. 

(EIA 2005) http://www.eia.doe.gov/neic/brochure/gas06/gasoline.htm

(Vitech Corporation 2007) Vitech Corporation. http://www.vitechcorp.com/ 

Whitehouse (2003) Hydrogen Fuel: A Clean and Secure Energy Future (January 30, 2003) 

http://www.whitehouse.gov/news/releases/2003/01/20030130-20.html

14 
15 

Biography 

Michael Duffy, PhD 

Michael Duffy is the Lead Systems Engineer for the National Renewable Energy Laboratory’s 

Hydrogen Program. He has a Ph.D. from the Ohio State University in Systems Engineering, an 

M.S. from Northeastern University in Engineering Management, a second M.S. from the 

Massachusetts Institute of Technology in Mechanical Engineering, and a B.S. from Tufts 

University in Mechanical Engineering. His background includes over 30 years of systems 

engineering experience as a consultant and Chief Systems Engineer in energy, safeguards and 

security, nuclear waste management, national defense, transportation, and space programs. Dr. 

Duffy has been a member of the International Council on Systems Engineering since 1992. 

Debra Sandor, PMP 

Ms. Sandor has ten years of process engineering experience in manufacturing and R&D 

organizations. She has a range of hands-on and theoretical experience, including scaling up pilot 

operations to full-scale production processes, process evaluation and validation, modeling of 

conceptual processes, and program and personnel management. As the Lead Systems Engineer 

for the DOE Biomass Program, she is responsible for maintaining the program’s integrated 

baseline and managing the development and implementation of the program’s system dynamics 

model. She holds a BS in Chemical Engineering from the University of Florida and a ME in 

Engineering Management from the University of Colorado. 
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From a supply chain view, this paper traces the flow of transportation fuels through required systems and addresses 

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hydrogen economy; system of systems; hydrogen transportation economy 

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