Jean-Paul Rodrigue (2013), New York:
Routledge, 416 pages.
Transportation and Energy
Authors: Dr. Jean-Paul Rodrigue and Dr. Claude Comtois
Human activities are closely dependent on the usage of several
forms and sources of energy to perform
work. Energy is the potential that allows movement and/or the modification
of matter (e.g. making steel by combining iron and carbon). The
energy content of an energy source
is the available energy per unit of weight or volume, but the
challenge is to effectively extract and use this energy. Thus, the more
energy consumed the greater the amount of work realized and it comes
as no surprise that economic development is correlated with greater
levels of energy consumption. There are four types of physical work
related to human activities:
There are enormous reserves of energy able to meet the future needs
of mankind. Unfortunately, one of the main contemporary issues is that
many of these reserves cannot be exploited at reasonable costs, such
as solar energy, or are unevenly distributed around the world, such
as oil. Through
the history of mankind's use of energy,
the choice of an energy source depended on a number of utility factors
which involved a transition
in energy systems from solid, liquid and eventually to gas sources
of energy. Since the industrial revolution, efforts have been made
to have work being performed by machines,
which considerably improved industrial productivity. The development
of steam engine and the generation and distribution of electric energy
over considerable distances have also altered the spatial pattern of
manufacturing industries by liberating production from a direct connection
to a fixed power system. While in the earlier stages of the
industrial revolution factories located close to sources of energy
(a waterfall or a coal field) or raw materials, mass conveyances and
new energy sources (electricity) enabled a much greater locational
Industrial development places large demands on fossil fuels. At
the turn of the 20th century, the invention and commercial development
of the internal combustion engine, notably in transport equipment, made
possible the efficient movement of people, freight and information and
stimulated the development of the global trade network. With globalization,
transportation is accounting for a growing share of the total amount
of energy spent for implementing, operating and maintaining the international
range and scope of human activities. Energy consumption has a strong
correlation with the level of development. Among developed
countries, transportation now accounts between 20 and 25% of the
total energy being consumed. The benefits conferred
by additional mobility, notably in terms of a better exploitation of
comparative advantages, have so far compensated the growing amount of
energy spent to support it. At the beginning of the 21st century,
the transition reached a stage where fossil
fuels, notably petroleum, are dominant. Out of the
world’s total power production, 87.1%
is derived from fossil fuels.
2. Transportation and Energy Consumption
Transportation and energy is a start a standard physics
application where giving momentum to masses (people, vehicles,
cargo, etc.) requires a proportional amount of energy. The relationship between transport and energy is a direct one, but
subject to different interpretations since it concerns
different transport modes, each having
their own performance levels. There is often a compromise between
speed and energy consumption, related to the desired economic returns.
Passengers and high value goods can be transported by fast but energy
intensive modes since the time component of their mobility tends to
have a high value, which conveys the willingness to use more energy. Economies of scale, mainly those achieved by maritime
transportation, are linked to low levels of energy consumption per unit
of mass being transported, but at a lower speed. This fits
relatively well freight transport imperatives, particularly for bulk. Comparatively, air freight
has high energy consumption levels linked to high speed services.
Transportation markets are particularly impacted by these three
- Modification of the environment. All the activities
involved in making space
suitable for human activities, like clearing land for agriculture,
modifying the hydrography (irrigation), and establishing distribution
infrastructures, as wells as constructing and conditioning (temperature
and light) enclosed structures.
- Appropriation of resources. Involves the extraction of
agricultural resources from the biomass and raw materials (minerals,
oil, lumber, etc.) for human needs. It also includes the disposal
of wastes, which are in an advanced industrial society very work
intensive to safely dispose of (e.g. collection, treatment and
- Processing resources. Concerns the modification of products from the biomass,
of raw materials and of goods to manufacture according to economic needs.
Over the last 200 years, work related to processing was considerably
mechanized (e.g. assembly lines).
- Transfer. Involves the movement of freight, people and
information from one location to another. It aims to attenuate the
spatial inequities in the location of resources by overcoming distance.
The less energy costs per ton or passenger - kilometer, the less
importance have transfers. Overcoming space in a global economy
requires a substantial amount of work and thus energy and has
consequently been subject to massive economies of scale.
A trend that emerged since the 1950s concerns the growing
share of transportation in the world's total oil consumption;
transportation accounts for approximately 25%
of world energy demand and for about 61.5% of all the oil used each
year. The impacts of transport on energy consumption are diverse, including
many that are necessary for the provision of transport facilities:
price level and
volatility of energy sources which are dependent on the
processes used in their
production. Stable energy sources are obviously preferred.
- Technological and technical changes in the
energy performance of transport modes and terminals. An
important goal is thus to improve this energy performance since
it is linked with direct economic benefits for both operators
(lower operating costs) and users (lower rates).
- Environmental externalities related to the
use of specific modes and energy sources and the goal to reduce
Energy consumption has strong modal variations:
- Vehicle manufacture, maintenance and disposal. The energy
spent for manufacturing and recycling vehicles is a direct function
of vehicle complexity, material used, fleet size and vehicle life
- Vehicle operation. Mainly involves energy used to provide
momentum to vehicles, namely as fuels,
as well as for intermodal operations. The
fuel markets for transportation
activities are well developed.
- Infrastructure construction and maintenance. The building
of roads, railways, bridges, tunnels, terminals, ports and airports
and the provision of lighting and signaling equipment require a
substantial amount or energy. They have a direct relationship with
vehicle operations since extensive networks are associated with
large amounts of traffic.
- Administration of transport business. The expenses involved
in planning, developing and managing transport infrastructures and
operations involves time, capital and skill that must be included
in the total energy consumed by the transport sector. This is particularly
the case for public transit.
- Energy production and trade. The processes of exploring,
extracting, refining and distributing fuels or generating and transmitting
energy also require power sources. The transformation of 100 units
of primary energy in the form of crude oil produces only 85 units
of energy in the form of gasoline. Any changes in transport energy
demands influence the pattern and flows of the world’s energy markets.
Further distinctions in the energy consumption of transport can be
made between passenger and freight movements:
- Land transportation accounts for the great majority of
energy consumption. Road transportation alone is consuming on average
85% of the total energy used by the transport sector in developed
countries. This trend is not however uniform within the land transportation
sector itself, as road transportation is almost the sole
mode responsible for additional
energy demands over the last 25 years. Despite a falling market
share, rail transport, on the basis of 1 kg of oil equivalent, remains
four times more efficient for passenger and twice as efficient for
freight movement as road transport. Rail transport accounts for
6% of global transport energy demand.
- Maritime transportation accounts for 90% of cross-border
world trade as measured by volume. The nature of water transport
and its economies of scale make it the most energy efficient mode
since it uses only 7% of all the energy consumed by transport activities,
a figure way below its contribution to the mobility of goods.
- Air transportation plays an integral part in the globalization
of transportation networks. The aviation industry accounts for 8%
of the energy consumed by transportation. Air transport has high
energy consumption levels, linked to high speeds. Fuel is the second
most important cost for the air transport industry accounting
for 13-20% of total expenses. This accounts for about 1.2 million
barrels per day. Technological innovations, such as more efficient
engines and better aerodynamics, have led to a continuous improvement
efficiency of each new generation of aircrafts.
3. Petroleum: The Transport Fuel
Almost all transportation modes depend on a form of the internal combustion
engine, with the two most salient technologies being the
diesel engine and the gas turbine, since
they are the lynchpin of globalization. While ship and truck engines
are adaptations of the diesel engine, jet engines are an adaptation
of the gas turbine. Transportation is almost completely reliant
(95%) upon petroleum products with the exception of railways using
electrical power. While the use of petroleum for other economic
sectors, such as industrial and electricity generation, has remained
relatively stable, the growth in oil demand is mainly attributed to
growth in transportation demand.
What varies is the type and the quality of petroleum derived fuel
being used. While maritime transportation relies on low quality
bunker fuel, air transportation requires a specialized fuel with
It is worth having a closer look at the chemical combustion principle
of hydrocarbons. For the majority of internal combustion engines, gasoline
(C8H18; four strokes Otto-cycle engines) serves
as fuel, but other sources like methane (CH4; gas turbines),
diesel (mostly trucks), bunker fuel (for ships) and kerosene (turbofans of jet planes) are used.
In a complete and perfect combustion of gasoline the following
chemical reaction is achieved:
- Passenger transportation accounts for 60 to 70% of energy
consumption from transportation activities. The private car is the
dominant mode but has a poor energetic
performance, although this performance has seen
substantial improvements since
the 1970s, mainly due to growing energy prices and regulations.
Only 12% of the fuel used by a car actually provides momentum. There
is a close relationship between rising income, automobile ownership
and distance traveled by vehicle. The United States has one of the
highest levels of car ownership in the world with one car for
every two people. About 60% of all American households owned
two or more cars, with 19% owning three or more. Another
trend has been the increasing rise in ownership of minivans, sport utility vehicles and light-duty trucks
for personal use and the corresponding decline in fuel economy.
Fuel consumption is however impacted by
implying that higher levels of fuel efficiency involve declining
marginal gains in fuel consumption. Also, the growth of vehicles-miles
travelled is correlated with
changes in energy prices and is entering a phase of maturity
in several developed countries.
- Freight transportation is dominated by rail and
the two most energy efficient modes. Coastal and inland waterways
also provide an energy efficient method of transporting passengers and
cargoes. A tow boat moving a typical load of 15 barges in tow holds the equivalent
of 225 rail car loads or 870 truck loads. The rationale for favoring
coastal and inland navigation is based on lower energy consumption
rates of shipping and the general overall smaller externalities
of water transportation. The United States Marine Transportation
System National Advisory Council has measured the distance that
one ton of cargo can be moved with 3.785 liters of fuel. A tow boat
operating on the inland waterways can move one ton of barge cargo
857 kilometers. The same amount of fuel will move one ton of rail
cargo 337 kilometers or one ton of highway cargo 98 kilometers.
Gasoline produces around 46,000 Btu per kilogram combusted, which
requires from 16 to 24 kg of air. The energy released by combustion
causes a rise in temperature of the products of combustion. Several
factors and conditions influence the level of combustion in an internal
combustion engine to provide momentum and keep efficient operating conditions.
The temperature attained depends on the rate of release and dissipation
of the energy and the quantity of combustion products. Air is the most
available source of oxygen, but because air also contains vast quantities
of nitrogen, nitrogen becomes the major constituent of the products
of combustion. The rate of combustion may be increased by finely dividing
the fuel to increase its surface area and hence its rate of reaction,
and by mixing it with the air to provide the necessary amount of oxygen
to the fuel.
If all internal combustion engines worked according to the above
equation, emissions and thus local environmental impacts of transportation
would be negligible (except for carbon dioxide emissions). The problem
is that combustion in internal combustion engines is imperfect
and incomplete for two reasons:
- (2) C8H18 + (25) O2
= (16) CO2 + (18) H2O + energy
In addition to the imperfect and incomplete combustion of hydrocarbons,
three major factors influence the rate
of combustion and thus emissions of pollutants, which are the characteristics
of vehicles (where technological improvements can play a role), driving characteristics
(where planning and regulation can play a role), and atmospheric conditions.
The internal combustion engine, mostly due to friction, converts
less than a third of the energy they consume into momentum. For
electric motors, this figure is above 80%.
4. Transportation and Alternative Fuels
All other things being equal, the energy source with the lowest cost
will always be sought. The dominance of petroleum-derived fuels is a result
of the relative simplicity with which they can be stored and efficiently
used in the internal combustion engine vehicle. Other fossil fuels (natural gas, propane, and methanol) can be used
as transportation fuels but require a more complicated storage system.
The main issue concerning the large-scale uses of these alternative
vehicle fuels is the large capital investments require in distribution
facilities as compared with conventional fuels. Another issue is that
in terms of energy density, these alternative fuels have lower efficiency
than gasoline and thus require greater volume of on-board storage to
cover the equivalent distance as a gasoline propelled vehicle if
performance is kept constant.
Alternative fuels in the form of non-crude oil resources are drawing
considerable attention as a result of shrinking oil reserves, increasing
petroleum costs and the need to reduce emissions of harmful pollutants.
The most prevalent alternatives being considered are:
- First, the fuel and the oxider are not pure, causing
an imperfect combustion. Although the refining process provides
a "clean" fuel, gasoline is known to have impurities such as sulfur
(0.1 to 5%), sometimes lead (anti-knock agent being phased out)
and other hydrocarbons (like benzene and butadiene), while air is
composed of 78% nitrogen and 21% oxygen. Thus, other
chemical components are part of the combustion process.
- Second, in part because of the first reason and in part because
of the technology of the engine, incomplete combustion emits
other residuals. Combustion in an engine occurs at an average
rate of 25 times per second, leaving limited time for a complete
combustion process. Besides carbon dioxide and water, a typical
internal combustion engine will produce carbon monoxide (CO), hydrocarbons
(benzene, formaldehyde, butadiene and acetaldehyde), volatile organic
compounds (VOC), sulfur dioxide (SO2), particulates,
and nitrogen oxides (NOx). These combustion products
are the main pollutants emitted in the environment by transportation.
The diffusion of non-fossil fuels in the transportation sector
has serious limitations. As a result, the price of oil will certainly
continue to increase as more expensive fuel-recovery technologies will
have to be utilized, particularly if demand for gasoline continues
to grow. But high oil prices
are deflationary leading to recession in economic activity and the search
for alternative sources of energy. Already, the potential peaking of conventional
oil production is leading to the implementation of coal derived oil
projects. Coal liquefaction technology allows the transformation of
coal into refined oil after a series of processes in an environment
of high temperature and high pressure. While the cost-effectiveness
of this technique as yet to be demonstrated, coal liquefaction is an
important measure in the implementation of transportation fuel strategies
in coal-rich countries, such as China and South Africa.
The costs of alternative energy sources to fossil fuels are higher
in the transportation sector than in other types of economic activities.
This suggests higher competitive advantages for the industrial, household,
commercial, electricity and heat sectors to shift away from oil and
to rely on solar, wind or hydro-power. Transportation fuels based on
renewable energy sources might not be competitive with petroleum fuels
unless future price increase is affected by different fuel taxes based
on environmental impacts.
5. Transportation and Peak Oil
The extent to which conventional non-renewable fossil fuels will
continue to be the primary resources for nearly all transportation fuels
is subject to debate. But the gap between demand and supply,
once considerable, is narrowing, an effect compounded by the
of global oil production. The steady surge in demand from
developing economies, particularly China
and India, requires additional outputs.
This raises concern about the capacity of major oil producers to meet
this rising world demand. The producers are not running out of oil,
but the existing reservoirs may not be capable of producing on a daily
basis the increasing volumes of oil that the world requires. Reservoirs
do not exist as underground lakes from which oil can easily be extracted.
There are geological limits to the output of existing fields. This suggests
that an additional reserves need to be found to compensate
for the declining production of existing fields. Reserves additions
in Alaska, off-shore West Africa or the Caspian sea basin are not enough
to offset this growing demand. The bitumen reserves in Alberta, Canada
for instance are estimated at 170 billion barrels, second in the world
in terms of oil reserves, behind Saudi Arabia. But extracting heavy
oil from sands bitumen necessitates much energy and water. The production
of 1 barrel of bitumen requires burning 10-20% of the energy content
of the resulting crude oil in the form of natural gas.
Others argue that the history of the oil industry is marked
by cycles of shortages and surplus. The rising price of oil will
render cost effective oil recovery in difficult areas. Deep water drilling, extraction from tar sands
and oil shale should increase the supply of oil that
can be recovered and extracted from the surface. But there is a limit
to the capacity of technological innovation to find and extract more
oil around the world and the related risks can be very high. Technological development does not keep pace with
surging demand. The construction of drilling rigs, power plants, refineries
and pipelines designed to increase oil exploitation is a complex and
slow process. The main concern is the amount of oil that can be pumped
to the surface on a daily basis. Some studies predict that carbon sequestration
in the form of CO2 capture and storage, if technically and economically
viable, could enhance the recovery of oil from conventional wells and
prolong the life of partially depleted oil fields well into the next
High fuel prices
could stimulate the development of
alternatives, but automotive fuel
oil is relatively inelastic. Higher prices result in very marginal
changes in demand for fuel. While $100 per barrel was for a long
time considered a threshold that would limit demand for automotive
fuel and lead to a decline in passenger and freight-km, evidence
suggests that higher oil prices had limited impact on the average
annual growth rate of world motorization. The analysis of the
evolution of the use of fossil fuels suggests that in a market
economy the introduction of alternative fuels is leading to an
increase in the global consumption of both fossil and alternative
fuels and not to the substitution of crude oil by bio-based
alternative fuels. This suggests that in the initial phase of an
energy transition cycle, the introduction of a new source of energy
complements existing supply until the new source of energy becomes
price competitive to be an alternative. The presence of both
renewable and non-renewable types of fuels stimulates the energy
market with the concomitant result of increasing greenhouse gas
emissions. The production of alternative fuels adds up to the
existing fossil fuels and does not replace it.
The main concern is the amount of oil that can be pumped to the surface
on a daily basis, especially where major oil fields have reached peak
capacity. Under such circumstances, oil prices are bound to rise in
a substantial way, sending significant price signals to the transport
market. How the transport system will respond and adapt to
higher energy prices is
obviously subject to much debate and interpretations. The following
potential consequences can be noted:
- Biogas such as ethanol, methanol and biodiesel can be
produced from the fermentation of food crops (sugar cane, corn,
cereals, etc.) or wood-waste. Their production however requires large
harvesting areas that may compete with other types of land use.
Besides, it is estimated that one hectare of wheat produces less
than 1,000 liters of transportation fuel per year which represents
the amount of fuel consumed by one passenger car traveling 10,000
kilometers per year. This limit is related to the capacity of plants
to absorb solar energy and transform it through photosynthesis.
This low productivity of the biomass does not meet the energy needs
of the transportation sector. In 2007, the US government proposed
to reduce oil consumption by 20% by using ethanol. As the US is
currently producing 26 billion liters of ethanol each year, this
objective would require the production of nearly 115 billion liters
of ethanol by 2017 which amounts to the total annual US maize production.
Besides, the production of ethanol is an energy-intensive process.
The production of 1 thermal unit of ethanol requires the combustion
of 0.76 unit of coal, petroleum or natural gas. Biodiesel can
obtained from a variety of crops. The choice of biomass fuel will
largely depend on the sustainability and energy efficiency of the
- Hydrogen is often mentioned as the energy source of the
future. The steps in using hydrogen as a transportation fuel consist
in: 1) producing hydrogen by electrolysis of water or by
extracting it from hydrocarbons; 2) compressing
or converting hydrogen into liquid form; 3) storing it on-board
a vehicle; and 4) using fuel cell to generate electricity on demand
from the hydrogen to propel a motor vehicle. Hydrogen fuel cells
are two times more efficient than gasoline and generate near-zero
pollutants. But hydrogen suffers from several problems. A lot of
energy is wasted in the production, transfer and storage of hydrogen.
Hydrogen manufacturing requires electricity production. Hydrogen-powered
vehicles require 2-4 times more energy for operation than an electric
car which does not make them cost-effective. Besides, hydrogen has
a very low energy density and requires very low temperature and
very high pressure storage tank adding weight and volume to a vehicle.
This suggests that liquid hydrogen fuel would be a better alternative
for ship and aircraft propulsion.
- Electricity is being considered as an alternative to
petroleum fuels as an energy source. A pure battery electric vehicle
is considered a more efficient alternative to hydrogen fuel propelled
vehicle as there is no need to convert energy into electricity since
the electricity stored in the battery can power the electric motor.
Besides an all electric car is easier and cheaper to produce than
a comparable fuel-cell vehicle. The main barriers to the development
electric cars are the lack of storage systems capable of providing
driving ranges and speed comparable to those of conventional vehicles.
The low energy capacity of batteries makes the electric car less
competitive than internal combustion engines using gasoline. An
electric car has a maximum range of 100 kilometers and speed of
less than 100 kph requiring 4-8 hours to recharge. Yet, as
technology improves, cost effective batteries will become
- Hybrid vehicles consisting of propulsion system using
an internal combustion engine supplemented by an electric motor and batteries,
provides opportunities combining the efficiency of electricity
with the long driving range of an internal combustion engine. A hybrid vehicle still uses liquid fuel
as the main source of energy but the engine provides the power to
drive the vehicle or is used to charge the battery via a generator.
Alternatively, the propulsion can be provided by the electricity
generated by the battery. When the battery is discharged, the engine
starts automatically without intervention from the driver. The generator
can also be fed by using the braking energy to recharge the battery.
Such a propulsion design greatly contributes to overall fuel efficiency.
Given the inevitable oil depletion, the successful development and
commercialization of hybrid vehicles appears on the medium term the most sustainable
option to conventional gasoline engine powered vehicles.
As the reality of peak oil steps in, the next stage is likely to
be a growing level of unreliability in the supply system as shortages
become more prevalent and common. At least, higher prices will trigger
notable changes in usage, modes, networks and supply chain management.
From a macro perspective, and since transportation is a very complex
system, assessing the outcome of high energy prices remains hazardous.
What appears very likely is a strong rationalization, a shift towards
more energy efficient modes as well as a higher level of integration
between modes to create multiplying effects in energy efficiency. As
higher transport costs play in, namely for
containers, many manufacturing
activities will reconsider the locations of production facilities to
sites closer to markets (near-sourcing). While globalization was favored by cheap and
efficient transport systems, the new relationships between transport
and energy are likely to restructure the global structure of production
and distribution towards regionalization.
- Road. As far as the automobile is concerned, higher oil
prices could trigger changes in several phases. Initially, commuters
would simply absorb the higher costs either by cutting on their
discretionary spending. Depending
on their level of productivity, many economies could show a remarkable
resilience. The next phase would see changes in commuting patterns
(e.g. carpooling), attempts to use public transit, a rapid adoption
of vehicles with high gasoline efficiency (in the United States,
this could mark the downfall of the SUV) and a search for other
transport alternatives. The existing spatial structure could also start
to show signs of stress as the unsustainability of car dependent
areas become more apparent. There is already evidence that
car mobility may have been reached in the United States. As high commuting costs and the inflationary
effects of high oil prices on the economy become apparent many would
no longer be able to afford living in a suburban setting. Cities
could start to implode. The trucking industry would behave in a
similar way, first by lowering their profits and their operating
expenses (e.g. scheduling, achieve FTL), but at some point, higher
prices will be passed on to their customers.
- Rail. This mode is set to benefit substantially from
higher energy prices as it is the most energy efficient land transportation
mode. Rail is about three times more energy efficient than trucking.
The level of substitution for passengers and freight remains uncertain
and will depend on the current market share and level of service
they offer. In North America, passenger rail has limited potential
while in Europe and Pacific Asia passenger rail already assume a
significant market share. For rail freight, North American freight
distribution has an advantage since rail account for a dominant
share of tons-km while this figure is less significant for other
regions of the world, mainly due to the distances involved and the
fragmentation of the system. In many cases, there could a pressure
towards the electrification of strategic long distance corridors
and the development of more efficient cargo handling facilities.
Thus, growing energy prices are likely to affect long distance rail
transportation differently depending on the geographical setting
and the conditions of the existing system.
- Air. This mode could be significantly impaired, both
for passengers and freight. Air transportation is a highly competitive
industry and the profit margins tend to be low. Fuels account for
about 15% of the operating expenses of an air carrier, but because
most of the other costs are fixed any variations in energy prices
is reflected directly on air fares. A long term increase in energy
prices, reflected in
jet fuel, is likely to impact discretionary air travel (mainly tourism),
but air freight, due to its high value, may be less impacted.
Technological developments are helping maintaining the
competitiveness of air transportation with
fuel efficient planes.
- Maritime. This mode is likely to be relatively unaffected
as it is the most energy efficient, but fuel is an important component
of a ship's operating costs. The response of maritime shippers over
higher energy prices tends to be lowering speed (slow steaming), which may have
impacts on port call scheduling. On the long run, higher energy
prices may however indirectly impact maritime transportation by
lowering demand for long distance cargo movements and incite port
calls at ports having the most direct and efficient hinterland connections.
In addition, this context may favor the development of short coastal
and fluvial services where possible.