Energy Efficiency of Ships

Introduction

The International Maritime Organisation (IMO), as the main regulatory body for shipping, has, in recent years, devoted significant time and effort in order to regulate shipping energy efficiency and thereby control the marine GHG emissions. For this purpose, IMO has developed a number of technical and operational measures that include:

• Energy Efficiency Design Index (EEDI);
• Energy Efficiency Operational Index (EEOI);
• Ship Energy Efficiency Management Plan (SEEMP).

Energy Efficiency Design Index (EEDI)

                The EEDI for new ships is the most important technical measure and it aims at promoting the use of more energy efficient equipment and engines. It is a non-prescriptive, performance based mechanism that leaves the choice if technologies to use in a specific ship design to industry.

For each new ship, new ship which has undergone a major conversion and new or existing ship which has undergone a major conversion that is so extensive that the ship is regarded by the Administration as a newly constructed the attained EEDI shall be as follows:

The Reference line values shall be calculated as follows:

The EEDI is expressed in grams of carbon dioxide per ship’s capacity-mile

The smaller the EEDI, the more energy efficient ship design.

The EEDI technical file contains the technical documentations which proves that the energy efficiency of the ship (attained EEDI) is below the allowed limit (required EEDI)

Energy Efficiency Operational Index (EEOI)

The Energy Efficiency Operational Index is a monitoring tool for managing ship & fleet efficiency performance over time.

Ship Energy Efficiency Management Plan (SEEMP)

Shipping is a relatively efficient mode of transport compared to land and air when you consider the CO2 emissions produced per mile that each tonne of cargo is transported. However, shipping is also coming under increased scrutiny to lower its GHG by the international community and, under its remit, the IMO is looking at promoting measures to control these by improving ship efficiency through better management and implementation of best practice. The SEEMP provides a means to formally capture processes by which a ship owner can seek to improve the environmental efficiency aspects of their operations both on-board each of their ships as well as company-wide.

There are four key processes that the SEEMP must address and describe and together they form a continuous improvement process

1.Planning

As part of each SEEMP, the ship owner is required to review current practices and energy usage on-board each ship with a view to determining any shortfalls or areas for improvement of energy efficiency. This is a crucial first step to developing an effective management plan.

2. Implementation

     Upon completion of the planning stage, a system of how each energy improvement measure is to be implemented needs to be developed

1. Monitoring

The SEEMP guidance recommends one internationally established tool in particular, that can be used for monitoring; the Energy Efficiency Operational Indicator (EEOI). This has been developed by the IMO to quantify the energy efficiency of a ship in terms of CO2 production per cargo tonne-nautical mile (g CO2 / t.nm)

2. Self-Evaluation and Improvement

Self-evaluation and improvement not only identifies how effective each energy improvement measure is, but it also determines whether the process by which it is implemented and monitored is suitable and how it can be improved

Methods for Energy Improvement

1. Reduce friction losses between hull and water.
   1. By painting
   2. Air lubrication system
   3. Cleaning interval and underwater inspection
2. Modification in propeller design
   1. High skewed propeller
   2. PTFE coating for propellers
   3. Big size propellers in accordance with main engine
3. Fitting of Mewis Duct: The duct straightens and accelerates the hull wake into the propeller and also produces forward thrust. The power saving is virtually independent of ship speed
   1. Energy saving up to 8%
   2. Low SO_x and CO₂ emissions
   3. No moving parts
4. Wake equalising duct (WED): it is a system for the improvement of ship propulsion and performance economy.
   1. Reduction of fuel consumption by 3-8%
   2. Reduction of vibration by about 50%
   3. Can be done afloat – no docking needed.
5. Waste heat recovery: Thermal heat loss from exhaust gases to generate electricity or propulsion via shaft motors.
6. Energy Management:
   1. Review of energy usage such as electrical and HVAC systems.
   2. Usage of LED lights wherever possible and feasible
   3. Cold ironing
7. Fuel efficient operations
   1. Improved voyage planning
   2. Just-In-Time
   3. Weather routeing
   4. Speed optimization
8. Non-conventional energy resources

International Energy Efficiency Certificate

• It is a newly introduced certificate that is mandatory for all vessels of 400 gross tonnage and above.
• The IEEC is not connected to survey scheme and does not have an expiry date.
• For new ships, an IEEC is to be issued at the vessel’s initial survey provided the EEDI has been verified and the SEEMP is on board
• For existing ships, the IEEC is to be issued on the first intermediate or renewal survey for the IAPP certificate (whichever comes first) on or after 01 Jan 2013 provided the SEEMP is on board.