Fossil Fuels and Renewable Energy for Ships

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Fossil fuels are the major energy sources in today’s world but still when over consumption takes place lead to disastrous effects such as air pollution and climate change. Burning of fossil fuels produces carbon dioxide, carbon monoxide, nitrogen monoxide, nitrogen dioxide, sulphur dioxide etc. that have severe bad effects on the habitats as well as affect human health.

Fossil fuels are non-renewable sources of energy as they are derived from pre-historic fossils and are no longer available if once used. Their source is limited and they are depleting at a faster rate. When extracted it poses a severe damage to the landscape as they are to be dig out from underground wells.

Pollution is the major disadvantage that is formed due to fossil fuels. When burnt they give out carbon dioxide, a greenhouse gas which is the main aspect of global warming. Rise in temperature of earth have resulted in melting of polar ice caps, flooding of low lying areas, rise in sea levels. If such conditions conquer the face of earth will face radical changes. By the transportation of fossil fuel (crude oil) by sea and the leakage of oil or accidental oil spills from ships can severely pollute the sea and do harm to the living things because its chemical constituents are poisonous. This can affect organisms both from internal exposure to oil through ingestion or inhalation and from external exposure through skin and eye irritation. Oil can also smother some small species of fish or invertebrates and coat feathers and fur, reducing birds’ and mammals’ ability to maintain their body temperatures.

Burning of fossil fuel releases Sulphur Dioxide gas which is the factor for acid rain. Acid rain leads to destruction of monuments made up of brickwork or marbles, even crops are affected due to acidification of loams.
The ozone layer is being damaged due to the release of greenhouse gases from the fuels. Hence, ozone holes are being created from which harmful UV rays enter the earth surface that affect human life causing diseases like cancer.
As the fossil fuels are extracted to an unlimited level it is for sure that they will deplete some day or the other. Since they are non-renewable it is likely that fuels expenses will face a hike in near future. There is a limited amount of these fuels available and we are not actually sure where that limit is.

Some potential advantages and disadvantages of the technology:

Advantages
1. Diesel engine technology is a well understood and reliable form of marine propulsion and auxiliary power generation technology.
2. The training of engineers to operate diesel machinery is well known and
facilities exist for the appropriate levels of education.
3. Engine manufacturers have well established repair and spare part networks around the world.
4. Diesel fuel in all grades has a worldwide distribution network and is easily
obtainable.
5. Many primary and secondary methods for reducing emissions which are
perceived to be harmful are now available. Furthermore, there is a
continuing programme of research and development being undertaken by the engine builders.
6. Diesel engines are generally able to cope with part load, transient and dynamic behaviour in a seaway.

Disadvantages
1. Diesel engines produce CO2 emissions as well as NOX, SOX, volatile organic compounds and particulate matter. Therefore, they have to be made compliant with the MARPOL Annex VI requirements and included during an EEDI evaluation of the ship.
2. The SOX emissions are a function of the sulphur content of the fuel used in the engine and to comply with regulations an abatement technology has to be employed.
3. There is now some contamination of the marine fuel supply by first-generation biofuels which needs to be carefully managed on board ships.

At present, renewable energy options are being considered for the global shipping fleet at all levels and in varying magnitudes, including: international and domestic transport of goods, people and services, fishing, tourism and other maritime pursuits. Renewable options can be used in ships of all sizes to provide primary, hybrid and/or auxiliary propulsion, as well as on-board and shore-side energy use. These clean energy solutions are being integrated through retrofits to the existing fleet or incorporated into new shipbuilding and design, with most applications deploying renewable energy as part of an integrated package of efficiency measures.
As per the study of DNV GL, a number of alternative fuels or energies are already used or could be potentially used in shipping in the future. These fuels are:
– Liquefied Natural Gas (LNG)
– Liquefied Petroleum Gas (LPG)
– Methanol and Ethanol
– Di-Methyl Ether (DME)
– Biodiesel
– Biogas
– Use of electricity for charging batteries and cold ironing
– Hydrogen
– Nuclear Fuel

LNG:

The burning of natural gas in internal combustion engines is not a new concept.
Neither is its use associated with diesel-electric propulsion or mechanical drive
systems for ships. A significant step in the adoption of natural gas as a fuel
has been the Dual Fuel Diesel-Electric systems on LNG carriers that are either
being built or already in service.
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.

Some potential advantages and disadvantages of the technology:

Advantages
1. LNG fuelling of reciprocating engines as a known technology and service experience, albeit limited at the present time, has been satisfactory.
2. The benefits in terms of CO2, NOX, SOX and the other emissions are significant.
3. Designs for suitable marine propulsion machinery systems exist.
4. It is relatively easy to convert many existing marine engines to burn LNG.
5. Currently LNG fuel is considerably cheaper than the conventional range of marine fuels.

Disadvantages
1. Methane slip has to be avoided during the bunkering and combustion processes of new and in-service engines since this is damaging in the context of GHG.
2. There is a general lack of a worldwide bunkering infrastructure at present.
3. LNG requires a heat source to evaporate it to form the gas. As well as using the inlet air to the prime mover, it may be possible to use a heat exchanger with sea water, but some fuel is likely to be needed to be burned to provide this low grade heat.

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 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.

Some potential advantages and disadvantages of the technology:

Advantages
1. Biofuels are potential alternatives to conventional fuels.
2. Synthetic fuels based on branch-chain higher alcohols and new types of algae and other microorganisms are a medium- to long-term possibility, given that production volumes can satisfy the demand from the marine and other markets.
3. Di-methyl ether shows some potential benefits as an alternative fuel.
4. Synthetic fuels can be derived from syngas, created by partial combustion of a wide range of biomass feed stocks.

Disadvantages
1. With the first generation of biofuels, biodiesel and bioethanol, problems have been experienced when used in the marine environment. However, this may not be the case with the second generation biofuels.
2. At the present time, significant land areas need to be devoted to first generation fuel production to satisfy the marine market.
3. The effective greenhouse gas emissions of all types of biofuels, including fuels derived from biomass, is currently an area of active research. It is possible that the available global resource of biomass and biofuels may be inadequate to supply shipping.
4. The production processes used at present to convert sugars and vegetable oils are not particularly efficient, but research is underway to enhance this aspect.
5. Further work is necessary to examine aspects of storage and handling of these fuels, and their impact on health, safety and the environment.
6. The presently perceived disadvantages of di-methyl ether in terms of its lubricity and corrosive issues together with creating sufficient production and supply require resolution.

HYDROGEN FUEL CELLS:

Hydrogen is a potential alternative fuel for ship propulsion. It requires energy to
produce hydrogen and this could come from either conventional fuels or nonfossil sources such as wind, hydro-electric or nuclear. Currently, all hydrogen used in industry is made from natural gas. In the case of conventional sources, in order to be effective in CO2 reduction the issue of whether the greenhouse gas emissions are simply being transferred from a source on the sea to one on land has to be adequately resolved as carbon sequestration and storage has yet to be demonstrated at scale.

A significant advantage of liquid H2 fuel is that it generates no CO2 or SOX emissions to the atmosphere. NOX emissions can be managed as for any other fuel, but where hydrogen is burned in a fuel cell, there are no NOX emissions. However, there are ship safety design issues which need resolution. These centre on the flammability of the fuel when stored; the necessary pressure vessels and cryogenic systems that would be required. These issues are similar to, but
more extreme than, those already required and which have been solved with LNG or LPG ships.

Some potential advantages and disadvantages of the technology:

Advantages
1. Liquid H2 generates no CO2, or SOX emissions to the atmosphere originating from the ship.
2. Uses land-based sources of power for creation.
3. Hydrogen can be used in fuel cells and internal combustion engines.
4. Burning it produces a large feed-stock in fresh water.

Disadvantages
1. Largely untried in the marine industry for propulsion purposes.
2. Hydrogen has some safety issues that need resolution.
3. It has a low energy density.
4. Would need a hydrogen supply infrastructure to make it viable for the marine industry.

LPG

A number of liquid fuels can be used in dual fuel engines, as substitute for oil. Some of the fuels that can be used are Liquefied Petroleum Gas (LPG –a 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.

Technology and Future Developments 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.

NUCLEAR POWER:

Nuclear propulsion in the future Nuclear propulsion has clear greenhouse
gas advantages and has been shown to be a practical proposition with naval
ships and submarines as well in certain specialised ships and demonstrator
projects. Considerable experience has been accumulated in the operation of PWR propulsion units, nevertheless considerable difficulty and cost would be incurred in developing a deep sea, international merchant ship today. The difficulties would arise from a number of aspects: design execution and planning, operation, training of crews and shore staff, nuclear regulation,
security, public perception, disposal and so on. It has been seen that the concept of small modular marinised reactor plants or molten salt reactors may attenuate many of these difficulties although not dispose of them. As such, it would be prudent to keep a watching brief on the development of these
technologies with a view to implementation in the medium to long term.
Some potential advantages and disadvantages of the technology:

Advantages:
1. Nuclear ship propulsion during operation emits no CO2, NOX, SOX, volatile organic components (VOC) and particulate emissions.
2. A significant documented body of experience exists in the design and
safe operation of shipboard nuclear propulsion plant: particularly in the case of PWR designs.
3. The nuclear power plant concepts are suitable for merchant ship propulsion.s
4. Small modular marinied reactor or molten salt reactor plants may attenuate many of the difficulties associated with nuclear propulsion although they will not dispose of them.
5. Nuclear propulsion would offer further flexibility for merchant ship design and operational planning with respect to ship speeds, hull form and ship numbers deployed on a route.
6. The costs of the fuel are initially paid for along with the reactor plant and thereby remove exposure to price fluctuations for significant periods of operational service.

Disadvantages
1. The conventional methods of planning, building and operation of merchant ships will need complete overhaul since the process would be driven by a safety case and systems engineering approach.
2. There would be a number of additional constraints imposed on the ship design and operation.
3. In contrast to the second advantage, there is a relatively small number of nuclear propulsion experts at all levels and this will cause competition with land-based installations.
4. In contrast to conventional methods of ship propulsion, there are further issues surrounding the deployment of nuclear technology which require resolution. These include international regulation, public perception, initial capital cost & financing, training & retention of crews, refuelling & safe storage for spent fuel and the setting up & maintenance of an infrastructure.

WIND ENERGY:

Methods that use the wind to provide energy to drive ships include a variety
of techniques. Typically these are Flettner rotors, kites or spinnakers, soft
sails, wing sails and wind turbines.

Wind is the cheapest, most powerful, and greenest source of energy on the high seas. With Sails, Kites or Flettner Rotors modern cargo ships can use the wind as a source of power – not only to lower fuel costs, but significantly reduce emission levels as well.

Sails or wind turbines propulsion is efficient, safe, and easy to use and the fact that wind is full free and cheaper installation cost makes most attractive technologies for simultaneously reducing operating costs and emissions. It is claimed that Skysails propulsion can save upto 15% and wind turbines Flettner Rotor Can save 30% t0 40% of fuel cost.

Saving fuel also saves emissions. Wind energy can reduce ship borne CO2 emissions while decreasing the output of such pollutants as SOx & NOx at the same time.

Some potential advantages and disadvantages of the technology:

Advantages
1. Power derived from the wind is free from exhaust pollutants.
2. Partial propulsion benefits can be achieved through wind-based methods.
3. Solar power has been demonstrated to augment auxiliary power.

Disadvantages
1. Wind power systems rely on the wind strength to be effective.
2. The use of some wind-based systems rely upon adequate control system
3. technology being installed on board the ship.
4. Applications involving power derived from the wind are limited to the augmentation of propulsion unless a full return to sail is contemplated for specific applications.
5. While a return to full sail propulsion is possible, this may have a number of adverse commercial and financial implications in some instances in terms of voyage times, number of ships required, etc.
6. Solar power availability is global position dependent.
7. Solar energy is feasible as an augment to auxiliary power but photovoltaic processes are inherently of low effectiveness, even under the best of conditions, and require a significant deck or structural area upon which to place an array of cells.

SOLAR ENERGY:

Photovoltaic methods offer an approach for limited amounts of power generation on board ships and trials have demonstrated that some benefit is available for auxiliary power requirements. However, the maximum contribution is small when compared with the power required to drive the ship (Mackay 2011).
The principal constraint is the ability to find a large deck surface area on the ship which does not interfere with cargo handling or other purposes for which the ship was designed. In this context car transporters are an obvious candidate for the application of this technology.
As such, coupled with a maximum attainable specific power from the sun at given global locations and the generally limited available deck area suggest that the power attainable would only be sufficient to augment the auxiliary power demands.
On the available area for energy capture from the sun by arrangements of solar panels on mast-like structures arranged along the deck, sometimes in combination with wind augmentation or the number of masts that can be accommodated is dependent on the type of ship and its duty as well the attitude of the panels with respect to the sun in order to maximise the panels’ effectiveness. It is likely that these arrangements will only be effective in the sense of an augment to auxiliary power requirements.
Some potential advantages and disadvantages of the technology:

Advantages
1. Power derived from the wind is free from exhaust pollutants.
2. Partial propulsion benefits can be achieved through wind-based methods.
3. Solar power has been demonstrated to augment auxiliary power.

Disadvantages
1. Wind power systems rely on the wind strength to be effective.
2. The use of some wind-based systems rely upon adequate control system technology being installed on board the ship.
3. Applications involving power derived from the wind are limited to the augmentation of propulsion unless a full return to sail is contemplated for specific applications.
4. While a return to full sail propulsion is possible, this may have a number of adverse commercial and financial implications in some instances in terms of voyage times, number of ships required, etc.
5. Solar power availability is global position dependent.
6. Solar energy is feasible as an augment to auxiliary power but photovoltaic processes are inherently of low effectiveness, even under the best of conditions, and require a significant deck or structural area upon which to place an array of cells.

HYBRID TECHNOLOGY:

Hybrid propulsion is an option where one or more modes of powering the ship can
be utilised to optimise performance for economic, environmental or operational
reasons. Most commonly today the different powering modes feed a common electrical bus bar from which power can be drawn for various purposes. This, however, need not necessarily be the case since many examples of mechanical linkages between independent power sources have been designed and operated in ships, both past and present.

At the end of July 2013, the 124-metre Prinsesse Benedikte – the largest hybrid vessel ever built, nicknamed the “Prius of the Sea” – is anticipated to go live with her new hybrid system on Denmark’s Rødbyhavn to Puttgarden route.

It is estimated that this hybrid diesel-electric propulsion system will use at least 20% less fuel for the ship than an equivalent diesel mechanical propulsion system operating at design speed with the vessel fully loaded. This fuel saving, in overall terms, relies on the shore power component being derived from renewable sources. There will also be consequent reductions in CO2 emissions and at lower speeds and light loaded conditions greater fuel savings can be achieved. In port
the ship is capable of operating on batteries only with zero ship-produced emissions.

Hybrid propulsion, therefore, permits a further degree of design flexibility to
enable a ship to be configured to equitably balance the constraints of economics and the environment by combining different power sources to meet the demands of the operational profile.

Advantages:
In this case the principal reasons for considering hybrid propulsion were:
1. greater redundancy
2. reduced fuel consumption
3. reduced impact of CO2 emissions and other pollutants
4. uncertainty of future fuel costs
5. insurance against increasing environmental legislation
6. noise reduction
7. possibility to operate in zero emission
8. mode when the ship is in port
9. lower maintenance

Disadvantages:
1. Initial high investment
2. The amount of batteries required for the system. A big room is required for batteries that is not available for cargo.
3. The batteries often are also very heavy and the latest batteries are very expensive.
4. The total system could be more complex than conventional propulsion systems.

References:
1. Future Ship Powering Options, Exploring alternative methods of ship propulsion by Royal Academy of Engineering.
2. alternative fuels for shipping (DNV GL strategic research & innovation position paper 1-2014)
3. www.ecomarinepower.com
4. www.imo.org
5. www.skysails.info

Written by Mohammud Hanif Dewan, IEng, IMarEng, MIMarEST, MRINA

Mohammud Hanif Dewan, IEng, IMarEng, MIMarEST, MRINA

Working as the Deputy Commandant at LMTI, Liberia and Assistant Consultant at IMO. Worked as the Lecturer at ALAM Malaysia, IMA & CMC Bangladesh. Sailed as Chief Engineer on board various types of Tankers in multinational companies. Also worked as a consultant for developing and preparation of new syllabuses of marine engineering pre-sea and post-sea courses of Department of Shipping, Bangladesh as per STCW 2010 Manila Amendments. Writer of maritime articles. Researcher on Energy Efficiency in Shipping Industry, UTM, Malaysia.