ECA Retrofit Study

New International Maritime Organization (IMO) regulations require that all vessels sailing in the Emission  Control Areas (ECA) must reduce sulphur level in fuel oil to 0.1% or clean the exhaust gas to an equivalent level by 2015.

The Danish industry initiative, Green Ship of the Future, has concluded a study on comparing technologies that meet the International Maritime Organization’s emission levels for ships sailing in the Emission Controlled Areas (ECA).

The objective of the study was to compare the potential solutions able to meet the requirements of the IMO regulations  regarding SOX in the ECA in 2015 and globally in 2020. Similarly in 2020, the global requirements will be a reduction of sulphur content in the fuel to 0.5% or alternatively the equivalent level measured in the exhaust gas.


The study was based on an existing 38,500 DWT tanker vessel, NORD BUTTERFLY, from D/S NORDEN. The study evaluated technical and economical feasibility of retrofit conversion into one of the following three operational modes in order to meet the future IMO regulations.

Low-sulphur fuel (MGO) – Base case

The base case is defined as the reference tanker in original as-built condition; in case of operation in ECA, the vessel will shift to low-sulphur fuel in order to comply with the prevailing emission requirements.

No major modifications are required in order to run on low-sulphur fuel, but for extended operation on MGO, it will be necessary to install a fuel cooler (the cost of such a cooler lies in the range of 30,000  – 50,000 USD.) to increase viscosity to a sufficient extent.

The total adaptation cost is considered negligible compared with the cost of purchasing MGO

Scrubber technology while operating on HFO

The exhaust gas scrubber system removes sulphur oxides and particulates from exhaust gas. The scrubber system is a hybrid system being capable of operation both on fresh water as well as sea water.

Scrubber installation principle
(source: Green Ship of the Future – ECA emission study)

The retrofitting of a scrubber system includes the following work on board the ship:

Removal of the following equipment and structures:

  1. Funnel structure from D-deck and upwards
  2. B-deck platform aft of funnel
  3. C-deck platform aft of funnel
  4. D-deck platform aft of funnel
  5. Exhaust gas pipes from D-deck and upwards
  6. Exhaust gas pipes for A/E from C-deck to D-deck
  7. Free fall life boat

Installation of the following equipment and structures:

  1. B-deck extension, pillars, ladder and platforms
  2. Sludge tank (internal structure tank)
  3. FW circulation tank
  4. NaOH compartment and tank
  5. C-deck extension, pillars, ladder and platforms
  6. Scrubber
  7. D-deck extension, ladder and platforms
  8. Free fall life boat
  9. Exhaust gas pipes, scrubber water pipes etc
  10. Funnel top structure
  11. Scrubber auxiliary machinery and pipe connections
  12. 440 V, 220 V, 24 V Electrical and automation installation

Left: Aftship as originally built – Right: Aftship with scrubber installed
(source: Green Ship of the Future – ECA emission study)

The scrubber alternative is attractive if the vessel is trading inside an ECA. The net present value and payback time is related to the price difference between HFO and MGO. For a cost differential of around $350/t, the payback time is

  1. around three years for 100% ECA operation,
  2. a little over four years for 75% ECA operation,
  3. six years for 50% operation and
  4. eight years for 25% operation in emissions control areas.

If a payback time of five years is considered acceptable, then the time spent inside an ECA would have to be at least 75%; in the case of 50% or less ECA time, it would be more attractive to shift to MGO. If the price differential between HFO and MGO is lower then the payback period increases.

LNG propulsion

The retrofitting of a LNG system is a major undertaking and includes the following work on board the ship:

Removal of the following equipment and structures:

  1. Deck pipes and electrical cable pipes in an area for LNG storage tank foundation and deck houses for LNG equipment
  2. Grating/platform in CL at A-deck in way of new LNG storage tank foundation

Installation of the following equipment and structures:

  1. Foundations for LNG storage tanks
  2. Deck houses for LNG equipment including foundation
  3. Rerouting/reinstallation of deck pipes, electrical cable pipes and pipe foundations
  4. New grating, platforms and ladders
  5. Foundations for new LNG pipe system
  6. Main engine conversion from MC-C to ME-GI
  7. Fuel gas supply system
  8. Block and bleed valve arrangement
  9. Gas piping system
  10. Ventilation system
  11. Inert gas system
  12. Sealing oil system
  13. LNG tank
  14. Fuel gas supply system
  15. LNG piping system and valves
  16. Auxiliary systems
  17. Safety equipment
  18. Instrumentation and control system

This alternative has many operational issues that should be taken into consideration. These may include but not limited to:

  1. specially trained crew,
  2. LNG bunkering procedures,
  3. safety during operation and bunkering,
  4. bunkering locations,
  5. gas venting,
  6. limited maximum range when running on LNG and
  7. maintenance of system components.

Left: Aftship with LNG tanks seen from the side – Right: Aftship with LNG tanks seen from the stern
(source: Green Ship of the Future – ECA emission study)

From a financial point of view the payback time is very sensitive to the LNG price under a number of assumed conditions. For instance:

  1. If LNG can be purchased at $100 or $200 less than the price of HFO, then the LNG alternative is financially attractive for ECA operation of at least 50%, assuming that a payback time of not more than five years is acceptable.
  2. If LNG prices are comparable to HFO at, say, $650/t, then LNG is attractive for vessels operating in ECAs 75% of the time.
  3. If LNG is more expensive than HFO, the LNG option is interesting only for very high operational percentages inside emissions control areas.
  4. If operating in ECAs a 100% of the time, then payback time is about three years at an MGO/HFO spread of $350/t and an LNG price of $100/t less than HFO. At 50% ECA operation, payback time is approximately seven years.
  5. If a five year payback time is desired, then the MGO/HFO spread would have to be $500/t.

The group behind the study consisted of Alfa Laval – Aalborg (former Aalborg Industries), D/S NORDEN, Danish Shipowners’ Association, Elland Engineering, Lloyd’s Register, Maersk Maritime Technology, Maersk Tankers, MAN Diesel & Turbo, Schmidt Maritime and with the Green Ship of the Future secretariat as coordinators. The project was jointly funded by the Danish Maritime Fund and the participating companies.

For more information regarding the study please refer to Green Ship of the Future as well as in the following links:

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