Aftertreatment technologies  

Any methane slip that can’t be prevented at the engine level needs to be minimised at the exhaust by using after treatment technologies, which will be further developed in the GREEN RAY project.  

Automatic Identification System (AIS)

AIS facilitates ship traffic monitoring in real time.  By using AIS data, the FMI could obtain a realistic traffic image for ship emission modeling.   


The HAZard IDentification is a safety review method where all the potential hazards get identified. The HAZID method serves as an exploratory approach as it does not yet provide solutions.  


The HAZard OPerability study looks into the potential hazards and also goes more in-depth into the safety review by providing solutions to the hazards found.   

IMO 2020

As of January 2020, the IMO 2020 regulations created by the International Maritime Organisation have come into effect. The regulations limit the amount of sulphur that is allowed in fuel from 3.5% down to 0.5%, a significant reduction. This has numerous benefits for air quality in and around coastal areas.  

IMO Tier III NOx limit  

The IMO Tier I, Tier II & Tier  III NOx limits aim to reduce the NOx emissions from ships within the NOx Emission Control Area in and around designated areas of the sea. Tier I and Tier II compliance can be achieved through targeted fuel optimisation and pre-combustion control technologies. GREEN RAY will achieve Tier III, which can be achieved with the use of low-pressure LNG engines. 

LNG injection system 

Using the patented LNG injection system, methane slip will be significantly reduced and fuel efficiency will be improved.  

Low-pressure dual fuel  

Low speed dual fuel aims to reduce the pressure of the 2-stroke engine. 

Dual fuel engines use LNG fuel in combination with lower sulphur level diesel fuel like marine diesel oil (MDO) or marine gas oil (MGO). With the low-pressure engine, the gas is injected at a pressure of up to 13 bar early in the compression stroke.  

Marine LNG Engine 

A marine LNG engine is a dual fuel engine that uses natural gas and a small amount of liquid fuel used for ignition to convert chemical energy into mechanical energy. Due to natural gas’s cleaner burning properties, the use of natural gas in merchant ship propulsion plants is becoming an option for companies in order to comply with IMO and MARPOL environmental regulations. 

Methane Oxidation Catalyst (MOC)

One way to reduce methane slip is by using a MOC to burn any methane uncombusted in the engine. This aftertreatment technology will be developed during the project.  

Methane slip 

Methane slip is unburnt methane that escapes into the atmosphere. If unaddressed it could offset the climate advantages of using LNG instead of diesel fuels.  


Nitrous oxide is a pollutant that forms during the combustion process in engines. NOx is harmful to people and the environment and is linked with the formation of acid rain. 

Particulate matter (PM)  

PM  refers to liquid or solid particle emissions that are airborne.  Most of the PM is formed through incomplete combustion of fuel and lubricant hydrocarbons in the engine. It is also created by aerosol processes during the cooling and dilution that occurs when the exhaust gas exits from the tailpipe. This, in combination with the particle formation in the engine, will result in the total particle emission dispersed in the atmosphere.  PM has been linked to cardiac and respiratory diseases.   

Ship Traffic Emission Assessment Model (STEAM)   

The STEAM model developed by the FMI provides fully dynamic ship emission inventories which reflect the changes in vessel routing and operation. 

Sulphur Guard Bed (SGB)  

The purpose of an SGB is to capture the SOx that escapes the engine via the exhaust. In this way, the SOx will not go to the following MOC unit, since the MOC is very sensitive to even small amounts of SOx in the exhaust.  

In LNG engines, the sulphur level is much lower than from any diesel fuels, so the SOx level in the exhaust of LNG combustion is very low – below any limit values. Even this low level affects the MOC. 

Sulphur Oxide (SOx)

Sulphur dioxide is a pollutant that is emitted during the combustion process in engines whose fuel contains sulphur. The fuel sulphur level is limited during the refining process, meaning that the higher the fuel grade, the lower the amount of SOx emitted. SOx is harmful to humans and the environment and is a major cause of acid rain.  

Technology Readiness Level  

The Technology Readiness Level (TRL) refers to the stage of readiness of a certain type of technology, with TRL 1 being the level where the basic principles have been observed and reported and TRL 9 being the highest level where the final technology has been tested and is ready for use.   

The GREEN RAY project aims to achieve TRL 7, which means to deliver a tested prototype.  

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