Green Marine Environmental Program
Courses by Topic
The ‘marine environment’ is used to describe our beaches, the entrance to rivers, coral reefs, the seas and oceans off the coastline. The ‘marine environment’ includes the millions of animals and plants that live in the seas and oceans. The air above the seas and oceans is included in the ‘the marine environment’.
Coastal areas and oceans are a vital resource for a sustainable world. Marine transportation accounts for 90 per cent of international trade. Exploitation of coastal and offshore mineral resources provides about 25 to 30 percent of the world’s energy supplies. Marine aquaculture represents a rapidly growing industry and accounts for 30 percent of the world’s fish consumption.
According to the current international legal classification of maritime areas, the World Ocean is divided into three legal categories of Maritime areas. Areas which are an integral part of a coastal state’s territory within the limits of its sovereignty that is – Internal waters, Territorial Seas. Areas, which are not included in the coastal state territory, but are under its jurisdiction that is – Exclusive economic zone, Contiguous zone and Continental shelf. Areas under neither sovereignty, nor jurisdiction of any state that is – High Seas Area.
There are many types of pollution that can harm the marine environment. However, the most common pollution of the sea comes from the land and not from ships. It has been estimated that 80% of the rubbish, chemicals and oil found in the sea actually comes from the land.
The types of pollution that may originate from ships include oil, chemicals, garbage sewage, air pollution from the ship’s engines and bunker fuel and the anti-fouling paint on a ship’s hull. Marine pests in ship’s ballast water or clinging to the ship’s hull can also harm new environments.
We are aware that more than 90% of the world’s merchandise is transported by sea. Operating of ships usually entails the carriage of ballast water by them, particularly in the interest of maintaining their stability, trim and structural integrity. The imminent outfall of needing to carry ballast water on board is that the water needs to be taken-in, i.e. ballasted at a certain sea-location and then, pumped-out, i.e. de-ballasted at another sea-location.
Ballast water (BW) is essential to control trim, list, draught, stability and stresses of a ship. Ballast water activities are largely regulated not only because of the above ship’s safety implications but also since they have been recognized to be a pathway for the movement of undesirable and alien bio-species from their natural habitat to other ecosystems.
The oceans of the world, which as we all know, are the source of various kinds of nutrition to mankind. However, these oceans are under threat from four fundamental sources – Aquatic invasive species, Physical alteration/destruction of the marine habitat, Over exploitation of the living marine resources and Land-based sources of marine pollution.
It is understood that around 7000 different Aquatic Invasive species are carried around in ship’s ballast water, during which, ballasting / de-ballasting operations are carried out. The chances of ultimate survival of the species that do survive these operations during the journey and are discharged to the sea, face a new habitat, which include predation and competition from the existing native species. It is however known that, when all factors are congenial, a newly introduced species may multiply, over-power and ultimately annex the native species. The entire eco-system may then be changed. This causes enormous damage to the local eco-systems, adversely affect bio-diversity and lead to heavy economic loss.
Sulphur oxides (SOx) – derive directly from the sulphur content of the fuels used. The sulphur in the combustion chamber is oxidised, principally forming sulphur dioxide (SO2). Ships generally use low quality residual fuel to reduce costs. This low quality fuel tends to have a high sulphur content.
Nitrogen oxides (NOx) – the formation of nitrogen oxides occurs as a result of oxidisation of molecular nitrogen in the combustion air or, to a lesser extent, in the fuel. Oxides of nitrogen are formed during the combustion process in diesel engines due to combination of nitrogen and oxygen from the air at these high temperatures.
Carbon dioxide (CO2) and water vapour – will be formed in all combustion processes in which complete or near complete combustion of a hydrocarbon fuel takes place. As such, the production of CO2 and water vapour is a function of the quantity of fuel burnt.
Particulate matter (PM) emissions are primarily formed by two separate mechanisms – Nuclei mode particles consist mainly of condensed hydrocarbons and sulphates, and accumulation mode particulates are formed during combustion by agglomeration of primary carbonaceous particles.
Reduction of Emissions of SOx and PM – The use of Low Sulphur Distillate Oil (LSDO) instead of Residual Fuel Oil (RFO) can reduce SOx gaseous emissions and the sulfate portion of the particulate matter (PM) emissions. The use of EGC technology is generally permitted as an alternative means of compliance to operating with these regulated low sulphur fuels. Scrubbers can be effective in complying with regulations that require the use of fuel with 1 percent or 0.5 percent sulphur content.
With regard to reducing the emissions of nitrogen oxides NOx, a typical SOx scrubber provides only a small reduction in NOx emissions and would not normally be considered a method for obtaining compliance with the NOx emission requirements. Use of Selective catalytic reduction (SCR) which is a relatively matured technology in land based systems and automobiles, have been deployed successfully on ships.
Measures to reduce CO2 emissions onboard include alternative energy sources such as gas, wind, second/third generation biofuels, Hybrid Auxiliary Power Generation, Change of Fuel Type, Waste heat recovery, High Efficient Marine Systems, ‘Cold Ironing’, Alternative propulsion, Hydrogen Fuel Cell Systems.
Low engine pollution has been promoted by adopting preformation and/or post formation emission control techniques such as the introduction of biodiesel, particulate ﬁlters, catalytic converters and water-in-fuel emulsion fuel. Out of these, water-in-fuel emulsion has been found to be the most economical solution that can be introduced in diesel engine without engine modiﬁcation. Efficient combustion and better fuel economy are the added advantages of water-in-fuel emulsion fuel.
Introduction of water vapours directly or indirectly into the combustion chamber, is one of the effective and most economical tool in reducing oxides of nitrogen (NOx) and particulate matter (PM) in the exhaust gases of diesel engines.
Water can be introduced into the combustion chamber in different ways – (a) introduction of water with the inlet air in liquid or vapour form, (b) parallel water and diesel injections, and (c) WiDE with or without surfactants.
While the first two methods of water introduction are subjected to additional cost of water injection system and engine corrosion problems, the latter method has been regarded as the most effective technique for the simultaneous reduction of both particulate matters and NOx. Moreover, WiDE is a convenient renewable fuel option as the existing engine does not require any prior or post modification.
Addition of water into the diesel combustion process is a known method to reduce NOx and, in some implementations, simultaneously reduce NOx and PM emissions. The very notion of introducing water into the cylinder of the diesel engine may sound controversial. After all, engineers have been taking great care to accomplish the exact opposite and protect the combustion chamber from water contamination, be it from the fuel or from water condensation in intake air coolers.
The disposal of waste oil, bilge and sludge generated in machinery spaces shall be completed onboard (by incineration or overboard discharge under 15 ppm). If such onboard disposal is improper or impossible, they shall be taken ashore for disposal at a shore receiving facility.
As per MARPOL Annex I, the discharge of oily water mixture from cargo spaces, slop tanks and pump rooms is permitted only when the following conditions are satisfied – The ship is not in a Special Area, the tanker is more than 50 nautical miles from the nearest land, the tanker is proceeding en-route, the instantaneous rate of discharge of oil content is not to exceed 30 litres per nautical mile, the total quantity of oil discharged is not more than 1/30,000 of the quantity of last cargo, the tanker has in operation an ODMCS and slop tank arrangement.
The discharge of oil from machinery spaces is permitted only when the following conditions are satisfied – The ship is not in a special area, the ship is proceeding en-route, the oil content does not exceed 15 ppm, the ship is fitted with a 15 ppm oily water separator and bilge alarm.
All oil tankers of 150 GRT and above must have an oil discharge monitoring and control system (ODME) installed. Monitors discharge of oily water from cargo slop tanks. Alarms and shuts down discharge if discharge rate exceeds 30 liters of oil per nm.
Machinery space oily water must be processed through approved oil filtering equipment per Reg. 14 to limit water oil content to 15 parts per million (ppm).
An Oil content monitor is a device for real time sampling and measuring of the oil content inn a moving stream of water.
The MARPOL Convention seeks to eliminate and reduce the amount of garbage being discharged into the sea from ships. Annex V applies to all ships, which means all vessels of any type whatsoever operating in the marine environment, from merchant ships to fixed or floating platforms.
Waste discharge into the sea is allowed by MARPOL under certain conditions. The discharged waste has to be noted down, in a waste disposal log stating the following information – The type of discharged waste, the amount of discharged waste, the time and position of discharge.
The special areas established under Annex V are sea areas where for recognized technical reasons relating to their oceanographic and ecological condition and the particular character of traffic, such as heavy maritime traffic, low water exchange, extreme ice states, endangered marine species, etc., the adoption of special mandatory methods for the prevention of marine pollution by garbage is required.
All ships of 100 gross tonnage and above, every ship certified to carry 15 persons or more, and every fixed or floating platform will have to carry a garbage management plan, which includes written procedures for minimizing, collecting, storing, processing and disposing of garbage, including the use of the equipment on board.
All ships of 400 gross tonnage and above and every ship which is certified to carry 15 persons or more engaged in voyages to ports and offshore terminals under the jurisdiction of another Party to the Convention and every fixed or floating platform to provide a Garbage Record Book and to record all disposal and incineration operations.
The Standard Specification for Shipboard Incinerators covers the design, manufacture, performance, operation and testing of incinerators designed to incinerate garbage and other shipboard waste.
The three most significant sources of ocean noise pollution are ship noise, oil and gas exploration and military sonar. Here we deal with underwater noise on account of maritime vessels, which come in many forms and are usually controlled by reducing the level of shipboard vibrations.
Large ships are constantly in motion, producing noises from their engines, propellers, generators and bearings. The problem with this noise is that it dominates the frequency ranges of 20-300Hz, the same range used by many species of whale. This makes it hard for them to communicate and, more dangerously, to distinguish ship noise from natural sounds. The consequence of this is accidental collisions, one of the leading causes of death for whales around the world.
There is a distinction between the types of noise that are generated by a ship. These are, self-noise and radiated noise. Self noise is the noise from all shipboard sources, generated by the subject vessel and considered in terms of the effect it has on the vessel’s own personnel and equipment. Radiated noise is the noise generated by the ship and experienced at some point which is distant from the ship by which its detection, recognition or influence on the environment could be initiated.
There are following five main methods by which a propeller can generate pressure waves in water and hence can give rise to underwater noise – the displacement of the water by the propeller blades, the pressure difference between suction and pressure-delivery surfaces of the propeller blade when these rotate, the flow over the surfaces of the propeller blades, the periodic fluctuation of the cavity volumes caused by operation of the blades in the variable wake field behind the vessel, the sudden collapse process associated with the life of a bubble formed by cavitation.
Many ships and underwater structures are protected from attachment of un- desired organisms by being coated with antifouling paints. Marine coatings have specific functional properties that provide superior corrosion protection to the surfaces on which they are applied. The coatings protect ships from sea water. Marine coatings also protect materials from corrosion and abrasion.
The measures to minimize corrosion are – Barrier coats, Shielding the metal from the atmosphere/ salt water by applying a coating film on it. This effectively destroys one leg of the corrosion triangle, either stopping existing corrosion or preventing corrosion cells from forming and Cathodic protection, preventing the steel structure from becoming an anode.
Hull fouling can be prevented by coating the underwater hull with antifouling paint. Antifouling coatings are specialized paints applied to the ship’s hull to slow the marine growth on the underwater area which can affect the vessels performance and durability. In addition to preventing marine growth, the hull coating can also act as a barrier against hull corrosion that will degrade and weaken the metal. It also improves the flow of water passing the hull.
Antifouling paint, applied to the underwater hull of ships, discourages or prevents the growth of organisms that attach to the hull. Its self-polishing resin and biocide, such as cuprous oxide along with a booster biocide, help to prevent biofouling organisms.
A self-polishing copolymer (SPC) antifouling paint will release biocide at a nearly constant rate throughout its life. The diffusion of the biocide on the hull surface is primarily due to a chemical reaction between the paint and seawater. The self-polishing mechanism of an antifouling paint film ensures a consistent renewal of paint film and release of biocide on the surface to prevent settlement and attachment of biofoulants.