The future mix of alternative marine fuels

POSITION PAPER 17-2014

AL
TERNATIVE
FUELS FOR
SHIPPING

SAFER, SMARTER, GREENER

3 POSITION PAPER

©Shutterstock

EXECUTIVE SUMMARY
This Position Paper provides an overview of the possible alternative fuels for marine propulsion.
Maritime transport accounts for over 80% of world trade by volume and for approximately 3%
of global greenhouse gas emissions, while it is also a contributor to air pollution close to coastal
areas and ports. In order to reduce the impact maritime transport has on climate change and on
the environment, a number of fuel efficiency measures, both on technical and on operational
levels, have to be adopted, including the introduction of alternative fuels. The immediate effect
of introducing alternative fuels will be a strong reduction in SOx, NOx, and PM, while greenhouse
gas reductions will also be possible, depending on what types of fuel are used. Fossil-based fuels,
such as LNG will have limited contribution to greenhouse gas reductions, while biofuels have the
potential to lead to drastic reductions. On a technical level, the introduction of alternative fuels will
be accompanied by additional complexity, in the areas of fuel supply infrastructure, rules for safe
use of fuels on board, and operation of new systems. It is expected that a number of different fuels
may become important in different markets around the world, depending on local availability of
fuels, which will add to the complexity. In this environment, the role of Classification Societies will
become increasingly important, in order to ensure the safe handling of fuels in shipping.

Contact Details:
Christos.Chryssakis@dnvgl.com
Prepared by:
Christos Chryssakis, Océane Balland,
Hans Anton Tvete, Andreas Brandsæter

Alternative fuels for shipping

CONTENT
EXECUTIVE SUMMARY

1

INTRODUCTION 2
DRIVERS AND CHALLENGES

4

Environmental Regulations and Environmental Concerns
Fuel Availability and Cost
Challenges and Barriers

4
6
7

OVERVIEW OF POTENTIAL ALTERNATIVES

8

LNG 9
Ship Electrification and Renewables
9
Biofuels 10
Hydrogen 11
Other Liquid or Gaseous Fuel Options
11
Nuclear Propulsion
12

WELL-TO-PROPELLER ASSESSMENT OF FUELS

14

The system boundaries and fuels studied
14
Uncertainties 17
Taking a Broader View
17

VISION FOR THE FUTURE

20

REFERENCES 22

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INTRODUCTION
The global merchant fleet currently consumes
approximately 330 million tonnes of fuel annually,
80-85% of which is residual fuel with high sulphur
content, and the remaining are distillate fuels
complying with stricter regulations. Upcoming
regulations regarding the sulphur content of marine
fuels, both in emission control areas and globally, are
likely to create increased demand for low-sulphur
fuels for shipping in the next five to ten years. The
advent of new regulations in the next decade can
lead to significantly increased fuel prices for distillate
fuels, while refinery capacity for producing distillates
can turn out to be insufficient for meeting the vastly
increasing demand. In addition, climate change
concerns will put increasingly more pressure on
shipping for reducing its greenhouse gas (GHG)
emissions. Both the demand for low sulphur fuels,
as well as the need for reduced GHG emissions can
be addressed by the introduction of alternative, low
carbon fuels.
Alternative fuels have been used in the
transportation sector in the past. In the 1920s a
process to convert coal, biomass or natural gas into
liquid fuels was invented by the Germans F. Fischer
and H. Tropsch, and became known as the FischerTropsch process. This process was heavily used in
the 2nd World War in Germany to produce liquid
fuels from coal, and also in South Africa during the

oil embargo in the 1970s and 1980s. Alternative
fuels came into the picture again in the 1970s for
reasons of security of energy supply. By the end
of the 1980s and 1990s growing concern about
the environmental impact of automobiles and of
anthropogenic emissions in general stimulated the
interest in alternative fuels.
There is a long list of fuels or energy carriers that
can be used in shipping. The ones most commonly
considered today are Liquefied Natural Gas (LNG),
Electricity, Biodiesel, and Methanol. Other fuels
that could play a role in the future are Liquefied
Petroleum Gas (LPG), Ethanol, Dimethyl Ether (DME),
Biogas, Synthetic Fuels, Hydrogen (particularly
for use in fuel cells), and Nuclear fuel. All these
fuels are virtually sulphur free, and can be used for
compliance with sulphur content regulations. They
can be used either in combination with conventional,
oil-based marine fuels, thus covering only part of a
vessel’s energy demand, or to completely replace
conventional fuels. The type of alternative fuel
selected and the proportion of conventional fuel
substituted will have a direct impact on the vessel’s
emissions, including GHG, NOx, and SOx.
When considering the overall impact of a given
fuel on the environment, it is important to take into
account not only the direct emissions from using


©Shutterstock

the fuel on board a vessel, but also emissions
related to the fuel’s production and transport
pathway. In addition, other effects, such as land
and water usage can become important for
certain types of fuels, especially for biofuels.
Quantitative information for these impact areas
can be collected and evaluated by performing a
Life Cycle Assessment (LCA) of marine fuels. This
allows for comparison between various pathways
along the energy value chain, and therefore for
the assessment of the potential impact compared
to marine diesel fuels.
This Position Paper provides an overview of the
possible alternative fuels for marine propulsion.
A discussion of drivers and barriers is given,
followed by a brief description of various fuels,
including technological challenges and potential
benefits from their use. The results of a lifecycle
assessment (Well-To-Propeller Analysis) are also
presented, focusing on GHG emissions. Finally,
a discussion on future applications concludes
this paper, indicating ways to overcome the
challenges and make a transition towards a more
sustainable future for shipping.

«This Position Paper provides
an overview of the possible
alternative fuels for marine
propulsion.»

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DRIVERS AND
CHALLENGES
The merchant world fleet gradually shifted from sail
to a full engine powered fleet from around 1870 to
1940. Steamships burning coal dominated up to
1920, and since then coal was gradually replaced
by marine oils, due to shift to diesel engines and
oil-fired steam boilers. The shift from wind to coal
was driven by the developments in steam engines,
and offered the opportunity for more reliable
transit times, to a large extent independent of the
weather conditions and prevailing wind directions.
The following shift, from coal to oil, was driven by
increased efficiency, ease of handling, and cleaner
operations.
The main drivers leading to the advent of alternative
fuels in the future can be classified in two broad
categories:
a. Regulatory requirements

and environmental concerns

b. Availability of fossil fuels, cost

nitrogen oxides (NOx) (IMO, 2008) from ship exhaust
gases and contains provisions for setting up special
SOx Emission Control Areas (ECAs), characterized by
more stringent controls on emissions as illustrated in
Figure 1. The ECAs currently include the North Sea
and the Baltic, and a zone extending 200 nautical
miles from the coastline of North America, see Figure
2. Other parts of the world can be included in ECAs
in the future. The most likely candidates today are
the Bosporus Straits/Sea of Marmara, Hong Kong,
and parts of the coastline of Guangdong, in China.
In addition to this, the EU will mandate 0.5% in EU
waters from 2020, irrespective of potential IMO
delay elsewhere, and it has already imposed a 0.1%
requirement in ports and inland waterways. Finally,
California also has special, stricter requirements in
place.
Ships operating in the ECAs have to use low sulphur
fuel, or alternatively implement measures to reduce
sulphur emissions, such as through the use of
scrubbers.

and energy security

ENVIRONMENTAL REGULATIONS AND
ENVIRONMENTAL CONCERNS
The International Maritime Organization (IMO) has
adopted a set of regulations for the prevention
of air pollution by ships, outlined in Annex VI of
the MARPOL Convention. MARPOL Annex VI sets
limits on the emissions of sulphur oxides (SOx) and

In addition, the Marine Environment Protection
Committee has agreed on a three-tier structure,
which would set progressively tighter NOx emission
standards for new marine engines, depending on the
date of their installation. The Tier III standards will be
enforced in the North American ECA only in 2016.
There is currently uncertainty with a potential Tier III
delay until 2021, which will be resolved at MEPC66 in
the spring of 2014.


Figure 1. MARPOL Annex VI fuel sulphur content limits

Regarding GHG emissions, two mandatory
mechanisms have been introduced, intended to
ensure an energy efficiency standard for ships:
1. The Energy Efficiency Design Index (EEDI),

for new ships
1. The Ship Energy Efficiency Management Plan

significantly to the cost of a ship. These systems are
both space-demanding and costly, while they can
increase the fuel consumption by 2-3%. On the other
hand, they allow for the use of less expensive, high
sulphur fuels. Thus, fuels that have the potential to
reduce emissions below required levels can play a
significant role in the future as substitutes for Heavy
Fuel Oil (HFO) and Marine Diesel Oil (MDO).

(SEEMP) for all ships

The EEDI is a performance-based mechanism that
requires newbuildings to fulfil a certain minimum
design energy efficiency rating pertaining to the
size of the vessels. Ship designers and builders are
free to choose the technologies to satisfy the EEDI
requirements for a specific ship design. The SEEMP
establishes a mechanism for operators to improve
the operational energy efficiency of ships.
The regulations apply to all ships of and above
400 gross tonnage and entered into force from
January 2013. Further regulations, such as emissions
monitoring, reporting and verification, are under
discussion, but no decisions have been taken yet.
Carbon pricing through e.g. emissions trading
remains a distant prospect.
Meeting the NOx and SOx regulations is technically
feasible, but can prove to be very costly. Introducing
exhaust gas aftertreatment systems, such as SOx
scrubbers and urea-based catalysts, can add

Moreover, the requirement for reduced sulphur content
in the fuel will also increase the cost of the fuel. This
effect will be more pronounced after 2020 (or 2025,
depending on when the new regulations will be
enforced), when the sulphur content globally will be at
0.5% (or 5,000 ppm), which is lower than current levels
for the ECAs. Introducing new, sulphur-free fuels can
be a viable solution for this problem, provided that
these fuels and the necessary technology are offered at
competitive price levels.
The fuel consumption in the ECAs is estimated at
approximately 30-50 million tonnes of fuel per year
and it is going to increase if more areas are included
in the ECAs in the future (Acciaro, 2012), (Sterling,
2012), (Wilson, 2012). These figures are important for
evaluating the potential of each one of the alternative
fuels presented in this report for replacing oil-based
fuels.

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©Shutterstock

FUEL AVAILABILITY AND COST
Estimates of future oil production vary and are
controversial. Advanced methods of oil extraction
start becoming economically feasible, due to
high oil prices in the last few years. The use of
unconventional resources, such as shale oil and tar
sands is gaining ground, while in the future there
may be enhanced pressure to expand oil and gas
activities in the Arctic. In the USA, the shale oil
production of recent years has reshaped the North
American energy market. Despite the potential
of the Arctic for future oil and gas production,
it is not clear how much the global production
could increase in the future. This is mainly due
to high costs and difficult conditions even with
reduced sea-ice. The potential consequences of an
accident in the Arctic could also be very severe.

Precise information regarding the location and
quantity of global oil reserves is difficult to obtain,
because many oil producing nations often make
public claims that cannot be easily verified. In
addition, the world largely depends on oil supplies
from potentially politically unstable regions, which
can have an adverse effect on fuel security. For
some countries, this is a major driver for developing
technology for exploitation of local unconventional
resources, such as shale oil and gas in USA, and for
investing in the development of biofuels, such as
ethanol in Brazil and in USA, and biodiesel in Europe.
CHALLENGES AND BARRIERS
So far, the shipping industry has not acted decisively
to realise its potential to reduce emissions via
low carbon energy. For some owners, finding
capital to fund proven fuel savings technologies


can be a challenge – even for technologies that
pay for themselves in a matter of years. When
introducing a new fuel, existing ships may have to
be retrofitted because of incompatible machinery.
This makes changes a long term investment. For
pioneers –owners who take the risk to invest in new
technologies solutions– unforeseen technical issues
often result in significant delays, requiring additional
capital.
At the same time, bunker costs for certain shipping
segments are paid for by the charterer, removing
incentives for owners to explore alternative fuels or
even fuel efficiency measures. Patchwork regulations,
enforced by different government bodies, and lack
of standards, have also slowed coordinated actions.
Lack of appropriate infrastructure, such as bunkering
facilities and supply chain, and uncertainty regarding
long-term availability of fuel are additional barriers

for the introduction of any new fuel. That is, owners
will not start using new fuels if infrastructure is not
available, and energy providers will not finance
expensive infrastructure without first securing
customers. Breaking this deadlock will require a
coordinated, industry-wide effort and the political will
to invest in the development of new infrastructure.
Patchwork regulations, enforced by different
government bodies, and lack of standards, have also
slowed coordinated action.
Lack of appropriate infrastructure, such as bunkering
facilities and supply chain, and long-term availability
of fuel are additional barriers for the introduction of
any new fuel. That is, owners will not start using new
fuels if infrastructure is not available, and energy
providers will not finance expensive infrastructure
without first securing customers. Breaking this
deadlock will require a coordinated, industrywide effort and the political will to invest in the
development of new infrastructure.

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OVERVIEW
OF POTENTIAL
ALTERNATIVES
DNV is studying a number of alternative fuels or
energy carriers that are already used or could be
potentially used in shipping in the future. These fuels
are:

understanding of these fuels and their potential
impact in the future:

¾¾ Liquefied Natural Gas (LNG)

¾¾ Production, availability and cost: information
on production methods, current production
volumes and prices, infrastructure, and future
forecast, where available

¾¾ Liquefied Petroleum Gas (LPG)

¾¾ Physical and chemical characteristics

¾¾ Methanol and Ethanol
¾¾ Di-Methyl Ether (DME)

¾¾ Applications and current status: applications in
the maritime and in other sectors. Overview of
technology including engines and storage tanks

¾¾ Synthetic Fuels (Fischer-Tropsch)
¾¾ Safety considerations
¾¾ Biodiesel
¾¾ Emissions and environmental considerations
¾¾ Biogas
¾¾ Use of electricity for charging
batteries and cold ironing
¾¾ Hydrogen
¾¾ Nuclear Fuel
For each one of these fuels the following information
is being collected in order to enhance our

While renewable energy (solar, wind) –may have
some potential to mitigate carbon emissions, this
is not seen as a viable alternative for commercial
shipping. Certainly, vessels equipped with sails, wind
kites or solar panels may be able to supplement
existing power generating systems, but the relative
unreliability of these energy sources make them
ill-suited for deep sea transport or operations in
some latitudes with seasonal weather conditions.
Likewise, nuclear power also remains problematic.


While a proven solution that produces no GHGs, the
perceived risks are considered too high for nuclear
power to be considered as a viable alternative for
ships.
Over the next four decades, it is likely that the
energy mix will be characterised by a high degree
of diversification. LNG has the potential to become
the fuel of choice for all shipping segments,
provided the infrastructure is in place, while liquid
biofuels could gradually also replace oil-based fuels.
Electricity from the grid will most likely be used more
and more to charge batteries for ship operations in
ports, but also for propulsion. Renewable electricity
could also be used to produce hydrogen, which
in turn can be used to power fuel cells, providing
auxiliary or propulsion power. If drastic reduction
of GHG emissions is required and appropriate
alternative fuels are not readily available, carbon
capture systems could provide a radical solution for
substantial reduction of CO2.
In this section, the fuels that will most likely be part
of the future energy mix for shipping are briefly
presented.

LNG
Using LNG as fuel offers clear environmental
benefits: elimination of SOX emissions, significant
reduction of NOX and particulate matter, and a
reduction of GHG emissions. It is an attractive option
as to meeting current emission requirements, but
it does not contribute to reducing CO2 emissions
to the levels that would be required for addressing
climate change. There are currently around 40 LNG
fuelled ships (excluding LNG carriers) in operation
worldwide, while another 40 new buildings are now
confirmed. LNG bunkering for ships is currently only
available in a number of places in Europe, Incheon
(Korea) and Buenos Aires (Argentina) but the world’s
bunkering grid is developing. The number of ships
is increasing fast and infrastructure projects are
planned or proposed along the main shipping lanes
of the world. One barrier for the introduction of LNG
is the increased demand for fuel tanks, leading to
a decrease in payload capacity. The relatively high
capital cost of the system installation is another issue.
Technology and Future Developments
LNG as fuel is now a proven and available solution,
with gas engines being produced covering a
broad range of power outputs. Engine concepts
include gas-only engines, dual fuel 4-stroke and
2-stoke. Methane slip (contributing to GHG) during

combustion is practically eliminated in modern
2-stroke engines, and further reductions should be
expected from 4-stroke engines. On the production
side, the recent boom in non-traditional gas (shale)
has had a dramatic effect on the market for gas,
particularly in North America. Exploitation of shale
gas in other parts of the world could also prove
to be significant for LNG. However, the extraction
process (hydraulic fracturing or “fracking”) remains
a controversial technology, due to growing public
concerns on its impact on public health and the
environment, regarding both air and water quality.
LNG uptake is expected to grow fast in the next 5 to
10 years, first on relatively small ships operating in
areas with developed gas bunkering infrastructure,
where LNG prices are competitive to HFO prices.
They will then be followed by larger ocean-going
vessels when bunkering infrastructure becomes
available around the world.

SHIP ELECTRIFICATION AND RENEWABLES
Recent developments in ship electrification hold
significant promise for more efficient use of energy.
Renewable power production can be exploited
to produce electricity, in order to power ships at
berth (cold ironing), and to charge batteries for fully
electric and hybrid ships. Enhancing the role of
electricity on ships will contribute towards improved
energy management and fuel efficiency on larger
vessels. For example, shifting from AC to on board
DC grids would allow engines to operate at variable
speeds, helping to reduce energy losses. Additional
benefits include power redundancy and noise and
vibration reduction.
If renewable energy from the sun or wind is not
readily available for electricity production on shore,
conventional power plants can be used. In this case
GHG and other pollutants will still be emitted, but
they can be reduced through exhaust gas cleaning
systems or carbon capture and storage. Alternatively,
nuclear power on shore could be used for emissionsfree electricity production, to be used for charging of
batteries on board.
Energy storage devices are critical for the use of
electricity for ship propulsion, while they are also
important for optimization of the use of energy on
board in hybrid ships. There are several energy
storage technologies currently available. Battery
powered propulsion systems are already being
engineered for smaller ships, while for larger vessels,

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engine manufacturers are focussed on hybrid battery
solutions. Challenges related to safety, availability of
materials used, and lifetime must be addressed to
ensure that battery-driven vessels are competitive
to conventional ones, but the pace of technology
is advancing rapidly. Other energy storage
technologies that can find application in shipping
in the future include flywheels, supercapacitors, and
thermal energy storage devices.
Electrification has generated strong interest,
particularly for ship types with frequent load
variations (Vartdal, 2013). Significant growth in
hybrid ships, such as harbour tugs, offshore service
vessels, and ferries should be expected after 2020,
and further applications for technology may be
applied to power cranes for bulk carriers or even in
ports. After 2030, improvements in energy storage
technology will enable some degree of hybridization
for most ships. For large, deep sea vessels, the
hybrid architecture will be utilised for powering
auxiliary systems, manoeuvring and port operations,
to reduce local emissions when in populated areas.

BIOFUELS
Biofuels can be derived from three primary sources:
edible crops, non-edible crops (waste, or crops
harvested on marginal land) and algae, which can
grow on water and does not compete with food
production. In addition to having the potential

©Shutterstock

to contribute to a substantial reduction in overall
GHG emissions, biofuels derived from plants or
organisms also biodegrade rapidly, posing far less
of a risk to the marine environment in the event of
a spill. Biofuels are also flexible: they can be mixed
with conventional fossil fuels to power conventional
internal combustion engines, while biogas produced
from waste can be used to replace LNG.
Biofuels derived from waste have many benefits,
but securing the necessary production volume
is a challenge. Consider that the land required
for production of 300 M Tonnes of Oil Equivalent
(TOE) biodiesel based on today’s (first and second
generation biofuels) technology is slightly larger
than 5 % of the current agricultural land in the
world. Algae-based biofuels seem to be the most
efficient and the process has the added benefit of
consuming significant quantities of CO2, but more
work needs to be done to identify alga strains that
would be suitable for efficient large scale production.
Concerns related to long-term storage stability of
biofuels on board ships, and issues with corrosion
also need to be addressed.
Experimentation with biofuels has already
started on large vessels, and preliminary results
are encouraging. However, advances in the
development of biofuels derived from waste or
algae will depend on the price of oil and gas. As a

©Shutterstock


result, biofuels will have only limited penetration in
the marine fuels market in the next decade. However
by 2030, biofuels are set to play a larger role,
provided that significant quantities can be produced
sustainably, and at an attractive price.

HYDROGEN
Renewable electricity can be employed to produce
hydrogen, which can be utilized to power fuel cells
on board ships. This solution will also help to deal
with the challenges associated with the intermittent
nature of many renewable energy sources. Hydrogen
is the smallest and lightest of all gas molecules, thus
offering the best energy-to-weight storage ratio of all
fuels. However, hydrogen as fuel can be difficult and
costly to produce, transport, and store. Compressed
hydrogen has a very low energy density by volume
requiring six to seven times more space than
HFO. Liquid hydrogen on the other hand, requires
cryogenic storage at very low temperatures (-253oC
or 20K), associated with large energy losses, and very
well insulated fuel tanks.
Fuel cells are the most commonly used devices
to convert the chemical energy of hydrogen into
electricity. When a fuel reformer is available, other
fuels, such as natural gas or methanol can be used to
power a fuel cell. Although operational experiences
have shown that fuel cell technology can perform

well in a maritime environment, further R&D is
necessary before fuel cells can be used to
complement existing powering technologies for
ships. Challenges include high investment costs, the
dimensions and weight of fuel cell installations, and
their expected lifetime. Special consideration has to
be given to storage of hydrogen on board ships, to
ensure safe operations.
Significant improvements in technology,
accompanied by cost reductions are required if
fuel cells are to become competitive for ships. With
the recent commercialisation of certain land-based
fuel cell applications, there is reason to believe that
costs will fall. For ship applications, reductions in size
and weight are also of immense importance, while
response at transient loads also remains a big issue.
Fuel cells can become a part of the future power
production on ships, and in the near future it might
be possible to see successful niche applications for
some specialised ships, particularly in combination
with hybrid battery systems.

OTHER LIQUID OR GASEOUS FUEL OPTIONS
A number of liquid fuels can be used in dual fuel
engines, as substitute for oil. Typically, a small
quantity of marine fuel oil is used as pilot fuel, to
initiate the ignition process, followed by combustion
of the selected alternative fuel. Some of the fuels that
can be used are Liquefied Petroleum Gas (LPG –a

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mixture of propane and butane), Methanol, Ethanol,
and Di-Methyl Ether (DME). Most of these fuels offer
significant reductions of NOx and Particulate Matter
emissions, while they are sulphur free and can be
used for compliance with ECAs regulations.

is one example where nuclear power is fully adapted.
In addition several nuclear powered navy vessels are
in operation today. Still, very few nuclear powered
merchant ships have ever been built, and all without
commercial success.

Marine engine manufacturers offer dual fuel
engines that can be operated with the fuel options
mentioned above. Depending on the type of
fuel, special designs for fuel tanks and piping are
required.

Electricity produced from nuclear power plants
onshore can also be used for cold ironing, for
charging batteries of pure electric ships, or for
providing the necessary energy for producing other
fuels, such as biofuels or hydrogen.

In July 2013 DNV released rules for using low
flashpoint liquid (LFL) fuels, such as methanol, as
bunker fuel (DNV, 2013). Interest in methanol as ship
fuel is growing in Sweden in response to the need
to reduce NOx and SOx emissions. Methanol has a
relatively low flashpoint, is toxic when it comes into
contact with the skin or when inhaled or ingested
and its vapour is denser than air. As a result of these
properties, additional safety barriers are required by
DNV.
The new mandatory notation LFL FUELLED covers
aspects such as materials, arrangement, fire safety,
electrical systems, control and monitoring, machinery
components and some ship segment specific
considerations.
Due to the limited availability of all these fuels, it
is not expected that they will penetrate deep sea
shipping sectors in the near to medium term future.
However, they can become important parts of the
fuel mix in local markets.

NUCLEAR PROPULSION
Nuclear power is a rather controversial technology
that can also be used in shipping, depending on
technology developments and social acceptance.
Nuclear material is defined by the International
Atomic Energy Agency (IAEA) as uranium, plutonium
and thorium. To avoid the possibility of making
weapons out of the nuclear material, nuclear
powered ships would need to run on low-enriched
nuclear material. Even though not considered a truly
sustainable energy alternative, due to the use of
limited resources, it has an obvious advantage of not
emitting any GHG’s, with the exception of emissions
related to handling of the nuclear materials.
Nuclear power can be used for propulsion on very
large ships, or on vessels that need to be selfsupporting for longer periods at a time. The Russian
ice-breaker fleet, operating in the northern sea route,

There are several concepts for compact nuclear
reactors being studied, ranging from 30MWe to
200MWe in power output, all with more than 10
years of service life. An important barrier that needs
to be overcome is related to safe storage and
recycling of spent fuel.
The use of Thorium as nuclear fuel (instead of
Uranium or Plutonium, utilized today), can also offer
significant advantages: higher fuel availability, higher
efficiency, and reduced nuclear waste production.
Thorium oxide can be mixed with 10% plutonium
oxide, which also offers a way to recycle plutonium.
The mix of thorium and plutonium oxide increases
the melting point and thermal conductivity, resulting
in safer reactors. An experimental Thorium reactor is
currently being tested in Norway, in order to evaluate
the feasibility of this technology.
Nuclear power is one of the most controversial
technologies for power generation and propulsion.
While the safety standards are very high and the
number of accidents very low, the consequences
of an accident can be devastating. Recent history
(the Three Mile Island, 1979, Chernobyl, 1986, and
Fukushima, 2011, accidents) illustrates the impact of
an accident in shaping public opinion and driving
policy decisions. The most recent example of this is
the abrupt change of direction in Germany with a
drastic scaling down of nuclear power immediately
after the accident in Fukushima in 2011.
Given the public opposition to nuclear power
in most countries, and fears related to potential
consequences from accidents, it seems very
unlikely that nuclear propulsion will be adopted in
shipping within the next 10-20 years. Nuclear power
generation on land will stay at today’s levels, mostly
due to developments in China. This picture could
change after 2030, provided that societal acceptance
increases, and other efforts to reduce GHG’s do not
prove as effective as desired.


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WELL-TOPROPELLER
ASSESSMENTS
OF FUELS
Alternative fuels can contribute significantly to
reducing the carbon footprint of shipping (Eide,
et al., 2012). To be able to comment on the
sustainability of fuels, quantitative data are required
to put things in perspective. This can be done by
performing Life Cycle Assessments (LCA) of marine
fuels, which allow for the comparison between
different fuel pathways along the energy value chain.
The results of an LCA can be used to assess the
environmental footprint of each fuel. These types of
assessments are complex and the chosen scenarios
highly influence the outcomes.
Whereas LCAs of alternative fuels for the automotive
sector, or so called Well-To-Wheel studies have been
performed for a long time now (Johannsson et al.,
1998), LCAs of alternative fuels for the maritime
transport sector, or so called Well-To-Propeller
(WTP) studies are relatively new (Bengtsson et al.,
2011). This is partly due to the recent focus on GHG
emissions from maritime transport activities and the
more restrictive upcoming regulations on both air
quality and GHGs.

Among the recent WTP studies available are those
performed at Chalmers University of Technology
(Bengtsson et al., 2011), for HFO, MGO, GTL FT
diesel, LNG and LBG, at TNO (Verbeek et al., 2011)
for LNG, HFO, MGO/MDO and EN590, as well as
the WTP Total Energy and Emissions Analysis for
Marine Systems Model (TEAM) model from the
Rochester Institute of technology (Winebrake et
al., 2006) for Residual Oil, conventional diesel, low
sulphur diesel, CNG, GTL FT diesel and biodiesel
from soybeans. The results of these studies show
that there are possibilities to reduce GHG emissions
from a lifecycle perspective, depending on the fuel
choice. Some fuels, such as CNG or FT-diesel, could,
depending on their production methods, actually
be worse than conventional diesel when it comes to
GHG emissions.
The current Well-To-Propeller study of alternative
fuels for the maritime transport assesses the
potential climate impacts of alternative fuel systems
at all stages in their life cycle – from oil & gas wells (or
from farming) to the propeller (Chryssakis, 2013).


The system boundaries and fuels studied
The system boundaries include the fuel production
cycle and the fuel use on-board the ship. The fuels
considered in this report, as well as the scenarios for
each fuel are summarized in Table 1. The following
assumptions are made:
¾¾ The boundaries between the technological
system and the natural world system begin at
the extraction point of the hydrocarbons and raw
materials. The final stage is combustion of the fuel.

¾¾ The geographical boundaries of the system
vary depending on the fuel value chain. They
typically include scenarios with fuel extracted and
produced in remote locations and transported
thousands of kilometres to the relevant market.
¾¾ Chronological boundaries are immediate
to short-term ones, with technologies and
scenarios feasible today or in the next 5 years.
The Well-To-Propeller analysis is carried out to
evaluate present impacts of existing alternative
fuels. Speculative technologies and far-fetched
scenarios have been avoided as much as possible.

Studied fields

Scenarios and System boundaries 1

HFO, MGO/
MDO, and low
sulphur diesel

Crude oil transported from oil region to Europe (8,000 km), refined and distributed there

■■ LNG produced onshore in Qatar and transported to Europe via LNG carrier
LNG

■■ FLNG facility offshore Australia and transport of LNG to market via
LNG carrier 10,000 km away

CNG

Natural gas is piped from Russia to Europe (7,000 km) where
it is compressed using EU electricity mix

LPG

LPG as a by-product of remote natural gas production and
shipped to Europe (10,000 km) via gas carrier

■■ Methanol produced near a remote natural gas field
Methanol

and transported to Europe via methanol tanker (10,000 km)

■■ Methanol produced from black liquor and transported to Europe
Ethanol

Ethanol produced from sugar cane in Brazil and shipped to Europe (10,000 km)

■■ DME produced close to a remote natural gas field and shipped to Europe via gas carrier

DME

■■ DME produced via black liquor gasification close to a pulp-mill and transported to Europe

FT diesel

FT diesel plant close to a remote natural gas field
and diesel transported to the market via product tanker

Biodiesel

European production of rapeseed oil and biodiesel production in the area

Raw

Vegetable
Production of rapeseed oil in Europe and used directly as fuel

Oil
Liquefied Biogas

Biogas produced in Europe from municipal waste and liquefied onsite

Nuclear propulsion

Nuclear fuel (U238) provision and its use on-board

Liquid Hydrogen

1

■■ Liquid hydrogen produced from renewables and distributed in the area
■■ Liquid hydrogen from reforming of Russian natural gas

Most of the shipping routes in this study are assuming a distance of about 10,000 km, unless otherwise indicated.

18

19 POSITION PAPER

During the life cycle inventory the only product considered is GHG emissions (amount of CO2 equivalent),
normalized with the energy content of the fuel (Mega Joule of fuel - 1 MJf). The contribution of various
GHG’s, for different time horizons, can be taken into account by converting into emissions of CO2 equivalent,
here in grams (gCO2eq), as presented in Table 2 (Foster et al., 2007). In this study the Life Cycle Assessment
is limited to Global Warming Potential, with a 100 years horizon (GWP100).

Emisssions

Gloval warming potential for given time horizon

CO2

20 years

100 years

500 years

Liquefied Biogas

1

1

1

Nuclear propulsion

72

25

7.6

Liquid Hydrogen

289

298

153

Table 2. Global Warming Potential of greenhouse gases considered in this report, relative to CO2

The GHG emissions associated with the combustion of renewable fuels are not accounted in the total
GHG balance. This is standard practice in similar published lifecycle assessments (Bengtsson et al., 2011,
Winebrake et al., 2006). The Well-To-Tank and Tank-To-Propeller results for the GHG emissions in gCO2eq/
MJf related to the different pathways for the maritime transport alternative fuels considered here are
displayed in Figure 3.

Figure 2. WTP GHG emissions results for marine alternative fuels.


It is noted that for LNG the calculations have been performed assuming a 4-stroke dual-fuel engine, which
results in a certain amount of methane slip, thus reducing its GHG benefits. It is expected that when LNG is
used in modern 2-stroke engines the methane slip is eliminated, leading to stronger GHG reductions.
Some of the fuels considered appear to be very attractive from a GHG emissions point of view; however it is
important to remember that all fuels are not equal when it comes to how much they cost at current market
prices. Many alternative fuels can be competitive in terms of prices with Low Sulphur Diesel. LNG seems
to be the most attractive price-wise, but costs of retrofitting or buying new LNG tanks and engines are not
negligible and should be taken into account. An expensive fuel may be more suitable for use in other sectors,
such as in automotive, where the market conditions could make it more attractive.

©Shutterstock

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21 POSITION PAPER

«... it is very unlikely that any new fuels will be introduced in ocean going vessels,
if a global supply infrastructure is not in place»

UNCERTAINTIES
There are many sources of uncertainty for each
one of the fuels considered. These are related to
differences in boundary limits (fuel production
and fuel combustion/use on-board a ship) and to
differences in the value chain (different production
methods, transportation, and distribution). Some
specific examples of uncertainties for WTT are
provided here:
¾¾ For the rapeseed oil based fuels, the GHG
emissions are dominated by the seed production
step, mostly through N2O emissions. This is
largely due to the fact that rapeseed crops require
a lot of nitrogen-based fertiliser, the related
emissions of which are very uncertain. This can
lead to variations of -7% to +43% in the WTT GHG
emissions (Edwards, 2011).
¾¾ For wood-based feedstock, the fertiliser and
energy needs are lower so the uncertainty is
decreased to -5% variation in WTT emissions for
DME from black liquor (Edwards, 2011).
¾¾ For oil and gas related processes, when electricity
is produced onsite, as in the case of liquefaction,
the process data are better documented and not
subject to a large uncertainty.
¾¾ In the case of future or cutting edge process like
GTL technology, the WTT uncertainty for total
GHG emissions is in the range of -10% to + 15%
(Edwards, 2011).

The uncertainty related to the combustion (Tank To
Propeller) of the alternative fuels is low; however,
different types of engines (2-stroke vs. 4-stroke)
can lead to different final results. Further work
utilizing different powertrains and operating profiles,
including hybrid systems, could result into greater
variations in results.

TAKING A BROADER VIEW
A more complete comparison can be performed
by including in the lifecycle assessment the
equipment required for producing and using the
fuels under consideration. An example could be the
environmental footprint of producing and disposing
a fuel cell, as compared to an internal combustion
engine. A few LCAs for marine fuel cell applications
have been carried out, for example by (Reenaas
2005), and (Alkaner & Zhou, 2006). Even though the
fuel cell technology is relatively new and production
volumes are low, compared to internal combustion
engines, the LCAs show that fuel cells can be
competitive from a GHG emissions point of view
(Ludvigsen & Ovrum, 2012).
Moreover, more pollutant emissions (NOx, SOx,
PM) and other side-effects of the use of alternative
fuels (such as land use and land use change,
use of fertilizers, etc.), should be considered. A
methodology for performing a LCA, including
a number of indicators has been developed by
(Vanem et al., 2012), and by (Roskilly et al., 2010).
This methodology introduces the concept of an
integrated LCA in order to facilitate the integration of
risk-based design and ecodesign of ships. In order to
make this efficient, it is proposed to monetize values
for all relevant indicators from such assessments. The
dimensioning indicators pertaining to ship design
have been identified and actual values have been
proposed in order to monetize the various indicators,
i.e. to efficiently convert all indicators to the common
denominator. One example of this methodology is
shown in Figure 4.


Figure 4. Spider diagrams are one way of
presenting the results of an LCA, here an
example from (Vanem et al., 2012)

An important concern when considering alternative
fuels is related to fuel availability and security of
supply. According to (US EIA International Energy
Outlook, 2011), 2,500 million tonnes of oil are
currently used in the transportation sector, and
the rest is used for power generation and the
petrochemicals industry. It is obvious from Table
3 that most alternative fuels are not produced in
sufficient volumes for large scale application in
shipping. This means that a number of different
alternative fuels could initially be used for short sea
shipping in local markets, where long term supply
can be guaranteed. This also offers a relatively
inexpensive way for testing these fuels in small
vessels. A recent representative example is the
plan of Stena Line for using methanol as a fuel for
ferries operating close to Sweden. However, it is
very unlikely that any new fuels will be introduced in
ocean going vessels, if a global supply infrastructure
is not in place.

Fuel

2010 total consumption
(million TOE/year)

Consumption for maritime transportation
(million TOE/year)

Oil

4,028

»330 HFO/MDO: »280/50

Natural Gas

2,858 of which LNG: 250-280

Very low (Approximately 40 vessels in 2013)

LPG

275

0

Methanol

23

0

Ethanol

58

0

DME

»3-5

0

Fischer-Tropsch

»15

0

Biodiesel

18-20

0

Liquefied Biogas

Very low

0

Nuclear (Uranium)

626

Very low

Hydrogen

Very low

0

Rapeseed Oil

5

0

Table 3. Global consumption volumes of various fuels in 2010. All figures in Tonnes of Oil Equivalent (TOE). Source: (BP, 2011)

22

23 POSITION PAPER

VISION FOR
THE FUTURE
The introduction of any alternative energy source
will take place at a very slow pace initially as
technologies mature and necessary infrastructure
becomes available. In addition, introduction of
any new fuel will most likely take place first in
regions where the fuel supply will be secure in
the long-term. Due to uncertainty related to the
development of appropriate infrastructure, the
new energy carriers will first be utilised in smaller
short sea vessels. As technologies mature and the
infrastructure starts to develop, each new fuel can
be used in larger vessels, and eventually on ocean
going ships, provided that global infrastructure
becomes available.
At present, LNG represents the first and most
likely alternative fuel to be seen as a genuine
replacement for HFO for ships built after 2020.
The adoption of LNG will be driven by fuel price
developments, technology, regulation, increased
availability of gas and the development of the
appropriate infrastructure. The introduction of
batteries in ships for assisting propulsion and
auxiliary power demands is also a promising low
carbon energy source. Ship types involved in
frequent transient operations (such as dynamic
positioning, frequent manoeuvring, etc.) can
benefit most from the introduction of batteries

through a hybrid configuration. Moreover, energy
storage devices can be used in combination with
waste heat recovery systems to optimise the use
of energy on board. Cold ironing could become a
standard procedure in many ports around the world.
The pace of development for other alternative
fuels, particularly biofuels produced from locally
available waste biomass, will accelerate, and may
soon compliment LNG and oil-based fuels. Indeed,
it is likely that a number of different biofuels could
become available in different parts of the world after
2030. However, acceptance of biofuels in deep-sea
transportation can only take place if these fuels can
be produced in large volumes and at a competitive
price around the world.
Maritime applications for renewable energy (solar,
wind) will certainly continue to be developed, but
it is unclear if these would have a significant impact
on carbon emissions. Nuclear power is not likely
to be a preferred alternative fuel beyond a few
niche segments, so is not expected to play a large
role in reducing carbon emissions. However, in the
event that the impact of climate change rises to a
level where required reductions in GHG emissions
become substantially larger, these technologies
could play a role.


There are many possible solutions to improve
sustainability for shipping in the future, but there
are still significant technology barriers. It is very
likely that in the future there will be a more diverse
fuel mix where LNG, biofuels, renewable electricity
and maybe hydrogen all play important roles.
Electrification and energy storage enable a broader
range of energy sources to be used. Renewable
energy such as wind and solar can be produced
and stored for use on ships either in batteries or as
hydrogen.
Besides IMO rules and ISO standards, development
of appropriate Rules and Recommended Practices
is necessary for the safe implementation of any of
these technologies in the future. To achieve this,
the role of Class Societies will be crucial. Adopting
new technologies is likely to be an uncomfortable
position for ship-owners. To ensure confidence that
technologies will work as intended, Technology
Qualification from neutral third parties, such as
classification societies, is also likely to be more
widely used.

©Shutterstock

J. Sterling, Head of Climate and
Environment for Maersk Line:
“The shipping industry needs to
dramatically reduce greenhouse
gas intensity in the coming
decades. In the short term, we
can gain a lot by focusing on
improving energy efficiency. In the
longer term, say 15 years or more,
we would like to see sustainable
biofuels become a commercially
available low-carbon fuel”, 2012

24


26

27 POSITION PAPER

REFERENCES

Acciaro M., Chryssakis, C., Eide, M.S., Endresen, Ø. “Potential
CO2 Reduction from Energy Mix Changes in the World Fleet”,
2012 International Association of Maritime Economists (IAME)
Conference, Taipei, Taiwan, 2012
Alkaner, S., Zhou, P. “A comparative study on life cycle analysis
of molten carbon fuel cells and diesel engines for marine
application”, J. of Power Sources, 158(1), pp.188-199, ISSN
0378-7753, 2006
Bengtsson, S. et al. “A comparative life cycle assessment of
marine fuels liquefied natural gas and three other fossil fuels”,
Department of Shipping and Marine Technology, Chalmers
University of Technology, Gothenburg, Sweden, 2011
BP, “BP Statistical Review of World Energy 2011”, 2011
Chryssakis, C., Stahl, S. "Well-To-Propeller Analysis of Alternative
Fuels for Maritime Applications", CIMAC 2013, Shanghai, China,
May 2013
DNV AS, “Tentative Rules for Low Flashpoint Liquid Fuelled Ship
Installations”, Rules for Classification, Ships / High Speed, Light
Craft and Naval Surface Craft, Part 6 Chapter 32, July 2013

Edwards, R. et al. “Well-to-wheels Analysis of Future Automotive
Fuels and Powertrains in the European Context “, Version 3c,
Report EUR 24952 EN - 2011
Eide, M., Chryssakis, C., Sverre, A., Endresen, Ø., "Pathways to
Low Carbon Shipping - Abatement Potential Towards 2050",
DNV Research & Innovation, Position Paper 14 - 2012
Foster, P. et al. “Changes in Atmospheric Constituents and in
Radiative Forcing”, Chapter 2, IPCC, 2007. http://www.ipcc.ch/
pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf
IMO, “Revised MARPOL Annex VI: Amendments to the Annex
of the Protocol of 1997 to amend the International Convention
for the Prevention of Pollution from Ships, 1973, as modified by
the Protocol of 1978 relating thereto”, MEPC.176 (58), London,
UK, 2008
Johansson, B. et al. “The economy of alternative fuels
when including the cost of air pollution”, Department of
Environmental and Energy Systems Studies, Lund University,
Gerdagatan 13, SE-223 62 Lund, Sweden, 1998
Ludvigsen, K.B., Ovrum, E. “Fuel cells for ships”, DNV Research
& Innovation Position Paper 13 - 2012


Reenaas, M. “Solid Oxide Fuel Cell Combined with Gas Turbine
versus Diesel Engine as Auxiliary Power Producing Unit onboard
a Passenger Ferry”, NTNU Master Thesis, 2005

Verbeek, R. et al. “Environmental and economic aspects of
using LNG as a fuel for shipping in the Netherlands”, TNORPT-2011-00166, 2011

Roskilly, A.P., Heslop, J. “Define KPI and Assessment Methods
for Environmental Aspects”, Pose2idon Project Deliverable
Report, UNEW.WP-A3.4_D049 V1.1, 2010

Wilson T. “Considering Biofuels for the Marine Market”, World
Biofuels Markets 2012, Rotterdam, Netherlands, 2012

Sterling J. “The role of biofuels in the shipping industry”, World
Biofuels Markets 2012, Rotterdam, Netherlands, 2012
US Energy Information Administration “International Energy
Outlook 2011”, DOE/EIA-0484, 2011
Vanem, E., Mangset, L.E., Psarros, G., Skjong, R. “Fan integrated
Life Cycle Assessment model to facilitate ship ecodesign”,
Advances in Safety, Reliability and Risk Management, Taylor &
Francis Group, London, ISBN 978-0-415-68379-1, 2012
Vartdal, B.-J. “Hybrid Ships”, DNV Research & Innovation
Position Paper 15 - 2013

Winebrake, J.J., Corbett, J.J., Meyer, P.E. “Total Fuel-Cycle
Emissions for Marine Vessels: A Well-to-Hull Analysis with
Case Study”, 13th CIRP International Conference on Life Cycle
Engineering, 2006

28

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Tel: +47 67 57 99 00
www.dnvgl.com

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safety and sustainability of their business. DNV GL provides classification and technical assurance along with software and
independent expert advisory services to the maritime, oil & gas and energy industries.
It also provides certification services to customers across a wide range of industries. Combining leading technical and
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The future mix of alternative marine fuels

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