As what is effectively a mobile community, every ship produces quantities of garbage from daily routines. In addition there is also waste products associated with some of the cargoes carried and from the upkeep and maintenance of the ship.
Among these will be food waste, packaging, dunnage, rags, containers for grease, paint, and other chemicals, rust scale, cargo sweepings and more. All of this has to be disposed of and while historically it would have been thrown over the side, this is no longer considered acceptable and there are rules concerning how this should be done.
Some waste can be discharged at sea but much cannot legally. MARPOL Annex V Prevention of Pollution by Garbage from Ships (entered into force 31 December 1988) deals with different types of garbage and specifies the distances from land and the manner in which they may be disposed of.
Just recently, the amount of plastics in the sea has become a globally recognized problem although most of the most dangerous – the so-called microbeads – are a product of the cosmetic industry and have little to do with shipping. Nevertheless, an important feature of Annex V is the complete ban imposed on the disposal into the sea of all forms of plastics.
In July 2011, IMO adopted extensive amendments to Annex V which entered into force on 1 January 2013. The revised Annex V prohibits the discharge of all garbage into the sea, except as provided otherwise, under specific circumstances. Getting rid of such waste costs money and it is likely that those costs have increased over the period since the 2011 amendments to MARPOL ANNEX V came into force on 1 January 2013. As well as the MARPOL rules, most coastal states have regulations concerning waste disposal at sea. The policing of these laws is variable but some states are diligent in enforcing them.
To reduce the quantity of waste materials produced and so reduce the cost of disposing it ashore a number of methods are employed. Incinerators or compactors were already installed on many ships allowing them to manage their waste but others have only simple facilities. Even for those ships fitted with incinerators, the 2013 regulations mean the ash residue is considered as garbage and should be disposed of ashore.
Where incinerators are considered they must be type-approved and are subject to IMO and flag state regulation. The IMO standard for incinerators is contained in MEPC.244(66) title 2014 STANDARD SPECIFICATION FOR SHIPBOARD INCINERATORS. It is not unknown for some ships to burn garbage in improvised systems but while this is something that has been done for generations, it is not permitted under MARPOL Annex VI (emissions to air) where it states:
Regulation 16 - Shipboard incineration
(1) Except as provided in paragraph (5), shipboard incineration shall be allowed only in a shipboard incinerator.
The paragraph 5 mentioned relates to burning sewage and oil sludge as a fuel in the main power plant or boilers
New categories of waste
The Annex V 2013 rules contained detailed descriptions of different waste types and where they may be discharged at sea. According to revised MARPOL Annex V shipboard generated garbage is to be grouped into the following categories:
1. Plastics – Garbage that consists of or includes plastic in any form, including synthetic ropes, synthetic fishing nets, plastic garbage bags and incinerator ashes from plastic products. Garbage under this category is prohibited to be discharged at sea.
2. Food wastes – Spoiled or unspoiled food substances. Food wastes may be discharged at sea under specific circumstances/requirements (refer to the simplified overview of the discharge provisions of the revised MARPOL Annex V developed by IMO).
3. Domestic Wastes – Garbage generated mainly in the accommodation spaces on board the ship (e.g. drinking bottles, papers, cardboard etc). Garbage under this category is prohibited
to be discharged at sea.
4. Cooking Oil – Edible oil or animal fat used for the preparation or cooking of food. Garbage under this category is prohibited to be discharged at sea.
5. Incinerator ashes – Ash and clinkers resulting from shipboard incinerators used for the incineration of garbage. Garbage under this category is prohibited to be discharged at sea.
6. Operational wastes – Solid wastes (including slurries) that are collected on board during normal maintenance or operations of a ship, or used for cargo stowage and handling. Operational wastes also includes cleaning agents and additives contained in cargo hold and external wash water that may be harmful to the aquatic environment. Operational wastes does not include grey water, bilge water, or other similar discharges essential to the operation of a ship (boiler/economizer blowdown, gas turbine washwater, machinery wastewater etc). Garbage under this category is prohibited to be discharged at sea.
7. Cargo residues – Remnants of any cargo which remain on the deck or in holds following loading or unloading. This category does not include cargo dust remaining on the deck after sweeping or dust on the external surfaces of the ship. Such garbage may be discharged at sea under specific circumstances/requirements (refer to the simplified overview of the discharge provisions of the revised MARPOL Annex V developed by IMO). It is essential to remember
that besides other requirements (e.g. distance from shore) cargo residues in order to be discharged at sea they should not be harmful to the marine environment. Cargo residues which are considered harmful to the marine environment are classified according to the criteria of the United Nations Globally Harmonized System for Classification and Labelling of Chemicals (UN GHS) meeting parameters such as: acute aquatic toxicity category 1,
chronic aquatic toxicity category, carcinogenicity, mutagenicity, reproductive toxicity etc
8. Animal Carcasses – Bodies of any animals that are carried on board as cargo and that die or are euthanized during the voyage. Discharge of such wastes permitted at sea under specific circumstances/requirements (refer to the simplified overview of the discharge provisions of the revised MARPOL Annex V developed by IMO).
9. Fishing Gear – Physical device that may be placed on or in the water or on the sea-bed with the intended purpose of capturing marine or fresh water organisms. Garbage under this category is prohibited to be discharged at sea.
Segregating the waste requires effective management on board and alongside the new discharge regulations is a requirement for every ship above 100gt to have in place a garbage management plan and to carry a record book detailing all aspects of waste handling and disposal.
A ship’s garbage management plan should contain a list of the particular ship’s equipment and arrangements for the handling of ship-generated garbage, and may contain extracts from and/or references to existing company instructions and manuals. In addition, a crew member has to be designated as the environmental control officer responsible for maintaining records and arranging disposal.
Any garbage that cannot be disposed of onboard will need to be sent to a shore waste facility any may need to be segregated. The most appropriate procedures for handling and storing garbage will vary depending on factors such as the type and size of the ship, the area of operation, shipboard garbage processing equipment and storage space, the number of crew or passengers, the duration of the voyage, and regulations and reception facilities at ports of call.
However, in view of the cost involved with the different garbage handling options, it is economically advantageous first to limit the amount of material that may become garbage from being brought on board the ship and, second, separate garbage eligible for discharge into the sea from other garbage that may not be discharged in this way. Limiting potential garbage can be done by requesting shipchandlers to remove unnecessary packaging from supplies taken in ports.
Several companies provide segregation and compacting plant suitable for any size of ship, although on small vessels it should be quite easy for the crew to fashion something suitable themselves. Compactors, baling presses, shredders, and crushers, can reduce the volume of ship generated waste by up to 90%. That is significant if the cost of shore disposal is taken into account.
As an example of the technology employed in commercial systems, one (the EVAC system) waste that can be burned is separated and first macerated and then passed into a briquetting unit which operates at 150bar pressure. The resulting briquettes is claimed to reduce waste volume by a factor of 10. Each individual briquette is small and easily handled but together they have a density of about 550-600kg/m3. Both the macerator and the briquetting unit have a foot print of around 4m2 and between them can handle up to 5,500kg per day making them suitable for vessels with large waste streams. The briquettes can be burned in an incinerator onboard or disposed of ashore.
Energy and fuel saving measures
Shipowners have always been careful about the amount of fuel used and except for meeting commercial commitments are usually keen to employ any means to reduce fuel use. In doing so they are indirectly contributing to reducing ships’ environmental impact. Despite this fact, shipping is often portrayed as being profligate in fuel consumption and it has become an accepted marketing tool for makers of all equipment and service providers to emphasise reduced environmental impact of their products.
Quite obviously the amount of emissions to air is directly related to the quantity of fuel used so any reduction in fuel use contributes to improving the environmental impact of ships. Many of the series of ShipInsight guides contain sections on energy saving measures with Power and Propulsion, Paints and Coatings and Shipping Software featuring the issue quite strongly. While there is no intent to duplicate that here, a brief resume of the issues is relevant.
In addition to individual items of equipment or ship systems, the design of the ship as a whole is of vital importance. In 2011, following some years of development, the IMO rules on energy efficient design came into effect. Known as the Energy Efficiency Design Index (EEDI), ships are obliged to meet a certain efficiency standard that becomes increasingly stricter over a period of time.
Since 1 January 2013, following an initial two-year phase zero, new ship design needs to meet the reference level for their ship type. The level is tightened incrementally every five years, and so the EEDI is expected to stimulate continued innovation and technical development of all the components influencing the fuel efficiency of a ship from its design phase. Following MEDPC 71 in July 2017, the IMO is considering bringing forward the final Phase 3 of EEDI from 2025 to 2022 and introducing a more stringent Phase 4 in addition.
The EEDI is a non-prescriptive, performance-based mechanism that leaves the choice of technologies to use in a specific ship design to equipment makers, shipbuilders and shipowners. As long as the required energy efficiency level is attained, ship designers and builders are free to use the most cost-efficient solutions for the ship to comply with the regulations.
The EEDI provides a specific figure for an individual ship design, expressed in grams of carbon dioxide (CO2) per ship’s capacity-mile (the smaller the EEDI the more energy efficient ship design) and is calculated by a formula based on the technical design parameters for a given ship.
Technology aimed at improving ship efficiency is frequently developed and employed partly to allow newbuildings to meet the EEDI requirements but mostly driven by operators desiring to reduce fuel costs. This is especially so when a vessel has already satisfied the EEDI requirement but the owner continues to add features improving efficiency beyond the compliance level.
Some have questioned owners’ commitment to making such improvements but there are good reasons why owners can benefit. Reducing fuel consumption when fuel costs are for the owner’s account is a clear saving but if the ship is time chartered then the owner is not responsible for providing fuel. Even so, the time charterers generally put fuel consumption high on the list of factors affecting choice of ship to charter and so a more efficient ship will have an advantage that can be a premium hire rate or the difference between employment and lay-up in a poor market. Every method of reducing fuel consumption that can be employed has the added environmental benefit of cutting exhaust emissions.
Achieving savings from fins to fouling reduction
Energy saving devices (ESDs) can come in many guises ranging from hull modifications, through to propeller/rudder combinations and appendages and adaptations to engines and machinery. Taking things a little further, the term can include means of exploiting energy
from the wind, sun and waves or storing excess power by way of batteries for use later.
Today, ESDs have become linked in the minds of many to the slow steaming strategies adopted by some operators – particularly in the container trades. While it is true that some devices such as turbocharger cutouts and concepts such as variable turbine geometry have come about simultaneously with slow steaming, their use can be extended to vessels for other reasons as well.
Several means of cutting fuel use were explored in the ShipInsight Guide to ESDs and employing one or more of the devices could lead to savings from 2% to 17%. In many cases the payback period is measured in months and not years.
Software too has a role to play in reducing fuel use and so cutting emissions. Two types of application in particular are worthy of particular consideration; Trim optimisation and weather routeing. Both have been heavily promoted by proponents of e-navigation although the need for such software has been questioned by some who believe that it undermines the knowledge and expertise of ships’ navigating officers.
Coatings used to protect against hull fouling have different environ mental impacts.
By preventing fouling they allow ships to burn less fuel and therefore play a role in reduction of exhaust emissions. However, even though TBT which was said to have had an adverse environmental effect causing problems for some marine organism has now been banned from use, some are saying that the copper-based substitutes are also hazardous.
Details on most of the current range of coatings and the technologies employed can be found in the ShipInsight Guide to Paints & Coatings. While criticisms are being directed at the replacement anti-fouling products for still having the potential to hard wildlife, the IMO has recognised the role that anti-foulings can have in preventing species transfer. In July 2011, the IMO issued RESOLUTION MEPC.207(62) “Guidelines for the control and management of ships’ biofouling to minimise the transfer of invasive aquatic species”. Currently the guidelines are purely advisory, although flag states are encouraged to ensure their use on board ships. It is expected that at some future date, the guidelines will become mandatory.
This expectation has increased recently as the IMO has pushed the question up the agenda now that the issue of ballast water treatment appears to have been finalised.