Power and propulsion system regulation

Updated 22 Oct 2019

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Unlike most other equipment on board vessels, as things stand there are no performance standards or guidelines for the power and propulsion systems beyond vague references to flag states’ requirements and a reference in the SOLAS regulation that calls for interim and special surveys to ensure the main machinery is in a satisfactory condition and fit for purpose.

There are, however, regulations that cover emissions from engines and efficiency rules that take into account the ship’s capacity to generate power. There have also been moves to limit a ship’s total power capacity as a means of moving towards the IMO’s declared goal of reducing and eventually eliminating CO2 emissions from ships.

The power and propulsion systems of ships are subject to various safety regulations but in most cases this is an indirect effect and has more to do with safe operations than the choice or type of engine and machinery.

From an operator’s point of view, engines, propulsion and steering arrangements – regardless of type – are all considered essential systems and therefore will feature in just about all approved ISM Code safety systems, adding another layer to any regulatory requirement for operation and maintenance. On the safety side, the fuel delivery to the engine may be controlled under SOLAS and, as a source for potential fire and explosions, the engine room will need fire protection and extinguishing systems.

The engine room is not a comfortable place to work but under the Maritime Labour Convention (MLC), which became effective in August 2013, noise and vibration are issues that all affected ships must take measures to control, both in accommodation and working areas. In July 2014, new SOLAS rules came into effect. These follow from the 91st meeting of IMO’s Maritime Safety Committee (MSC 91) in November 2012 when the IMO adopted a new SOLAS regulation II-1/3-12 to require new ships to be constructed to reduce on-board noise and to protect personnel from noise.

The new limits are in accordance with the revised Code on Noise Levels Onboard Ships, which sets out mandatory maximum noise level limits for machinery spaces, control rooms, workshops, accommodation and other spaces. The code supersedes the previous non-mandatory code, adopted in 1981 by resolution A.468(XII). It applies to all vessels of 1,600gt or more which:

• are built under a contract signed after 1 July 2014;

• with the keel laid after 1 January 2015;

• have a delivery date on or after 1 July 2018.

As an example of operational regulations, the propulsion engines of ships will produce the exhaust emissions that are controlled by Annex VI of MARPOL and in the case of NOx there is some potential for a direct impact on the engine, depending upon the method chosen to prove compliance.

Likewise, the Energy Efficiency Design Index (EEDI) may require the main engine’s power output to be restricted in some way in order to meet the CO2 limitations if no other means are available to do so. The EEDI rules introduced by the IMO in 2013 to reduce shipping’s CO2 output, form a non-prescriptive, performance-based mechanism that leaves the choice of technologies to use in a specific ship design to the owner and, 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 grammes of CO2 per ship’s capacity-mile and is calculated by a formula based on the technical design parameters for a given ship.

The options for reducing the CO2 emissions are many and most are not related to the ship’s engines. Energy-saving measures include improved hull forms and better propulsion systems, including measures aimed at improving flow into and out of propellers. More innovative options include air lubrication systems built into the hull and devices such as Flettner rotors that can reduce fuel use in certain conditions. Energy storage systems or batteries are other options.

The effect of the EEDI in reducing CO2 output is designed to become more stringent over time. From an initial ‘Phase 0’ (2013-2015) aimed at setting benchmarks, there follow three five-year periods in which the allowed CO2 levels are reduced by 10% each time. The Phase III stage was made more stringent in 2018 with the introduction date for the final phase being brought forward for some ship types and sizes and the emission reduction level increased from 30% to 40 or even 50%. It is also expected that more phases will be added.

Regulation also comes at a national level under port state rules. Where national regulation is concerned, there are developments such as the Norwegian NOx Levy and Fund, EU regulations and the California Air Resource Board’s (CARB’s) attempts to limit and measure emissions above and beyond that required under IMO rules. In addition, so long as a ship is registered with a classification society, there are the rules and requirements of its class society that need to be considered.

Decarbonisation targets

Much more of a threat to the dominance of the diesel engine in shipping will arise if the IMO acts on its ambitions to decarbonise the shipping industry. At MEPC 72 in April 2018, the IMO announced an ambitious (some might say impossible) ‘Vision’ for decarbonising the shipping industry. In particular, it set out the following programme of ambitions:

  • Carbon intensity of the ship to decline through implementation of further phases of the energy efficiency design index (EEDI) for new ships. Review with the aim to strengthen the energy efficiency design requirements for ships with the percentage improvement for each phase to be determined for each ship type, as appropriate;
  • Carbon intensity of international shipping to decline. To reduce CO2 emissions per transport work, as an average across international shipping, by at least 40% by 2030, pursuing efforts towards 70% by 2050, compared to 2008; and
  • GHG emissions from international shipping to peak and decline. To peak GHG emissions from international shipping as soon as possible and to reduce the total annual GHG emissions by at least 50% by 2050 compared to 2008 whilst pursuing efforts towards phasing them out, as called for in the Vision as a point on a pathway of CO2 emissions reduction consistent with the Paris Agreement temperature goals.
  • Quite obviously this ambitious plan would require an end to most hydrocarbon fuels which would include oils, LNG and even biofuels. An internal combustion engine is able to run on fuels that do not contain carbon but so far the only such fuel that has been used is hydrogen, and that only in experimental and prototype engines.

As a fuel, hydrogen is best suited to use in fuel cells rather than internal combustion engines because it has undesirable properties such as making metals brittle and even being able to diffuse through metal. Another alternative that is being spoken about is ammonia, which consists only of nitrogen and hydrogen.

Talking of targets, as the IMO has done, does not necessarily mean that diesels will no longer be viable. Some progress towards the targets could be achieved by a switch to LNG but the most likely outcome if the targets become mandatory would be that use of diesel engines and hydrocarbon fuels would be limited to vessel types best suited to operation with them, with other ships having to adopt alternatives such as fuel cells or batteries for short-sea use.

NOx emissions

It is now two years since the last of the deadlines under the NOx regulations came into effect but new ECAs are still on the cards, extending rules to newbuildings at different rates.

The demands of MARPOL Annex VI are covered elsewhere in the ShipInsight range of articles and publications – most specifically under the Environmental Technology section. However, and to recap, the requirements of the NOx Code are the only emission regulations in which the engine itself rather than the fuel or ancillary systems can be a controlling factor. Under the code, all vessels built since 2000 must have a Technical File that identifies the engine’s components, settings or operating values that influence exhaust emissions.

The file is prepared by the engine maker and approved by the flag state. It must be retained onboard for the whole life of the engine and will be used to ensure compliance.

The engine to which the Technical File refers is to be installed in accordance with the rating (kW and speed) and duty cycle as approved, together with any limitation imposed by the Technical File. The Technical File must, at a minimum, contain the following information:

  • Identification of components, settings and operating values of the engine which influence its NOx emissions;
  • Identification of the full range of allowable adjustments or alternatives for the components of the engine;
  • A full record of the engine’s performance, including its rated speed and rated power;
  • A system of onboard NOx verification procedures to verify compliance with the NOx emission limits during onboard verification surveys;
  • A copy of the test report for an engine tested for pre-certification or a test report for an engine installed onboard ship without pre-certification;
  • If applicable, the designation and restrictions for an engine which is a member of an engine group or engine family;
  • Specifications of those spare parts and components which, when used in the engine, according to those specifications, will result in continued compliance of the engine with the NOx emission limits;
  • The Engine International Air Pollution Prevention Certificate (EIAPP).

The permitted NOx emission levels have gradually reduced under three steps or Tiers. The last of these, Tier III, became effective in 2016 since when all new ships have had to comply with its requirements when operating in emission control areas. Replacement engines fitted to existing ships will also need to meet the new levels unless the engine is second hand.

As of November 2019, the only two IMO emission control areas where Tier III applies are the North American ECA and The United States Caribbean Sea ECA. The Baltic and North Sea sulphur emission control areas will be upgraded to full ECAs on 1 January 2021 and from that time all newbuild vessels operating in those zones must have engines complying with Tier III emission levels. There is the very real possibility of new emission control areas being established in the future and the dates for compliance will be set for such areas as they are established. Only new ships built after the establishment of new ECAs must comply.

Compliance with the code can be achieved using one of three options alone or in combination. The first option is to run the engine always within the parameters as laid down in the technical file and to use only OEM spare parts when any component identified in the technical file requires replacement.

The second is to install a continuous monitoring system of the type offered by manufacturers such as Kittiwake, Martek Marine, Green Instruments and Norsk Analyse, among others. Some of these systems can measure other exhaust gases and might be able to provide evidence of compliance with other regulations such as SOx emissions limits in SECAs or in ports where low-sulphur fuel is mandated.

The third option requires the engine to be tested at regular intervals by approved service providers. All engine types and power configurations are affected by these regulations although engines running on LNG and some of the latest alternatives such as methanol or ethane do not produce SOx. The regulation of engines using LNG and similar fuels has only recently come under the auspices of the IMO having previously been down to flag states to set rules on a case-by-case basis. More details of the IMO rules are included in the section on dual-fuel and gas burning engines.

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