Periodic Reporting for period 2 - GREEN RAY (New GeneRation marinE ENgines and Retrofit solutions to Achieve methane abatement flexibilitY)
Berichtszeitraum: 2023-12-01 bis 2025-05-31
Liquid natural gas (LNG) utilization in shipping is increasing and has direct effects, namely benefits on air quality and human health when comparing to oil-based marine fuels. Moreover, CO2 emission is lower with gas use compared to diesel fuels. The low-pressure dual fuel concept is the most popular LNG engine technology for large-bore marine engines, which, however, is often associated with elevated levels of methane slip. Therefore, development of methane slip reduction technologies for these low-pressure dual fuel cases is the focus of this project.
There are two main objectives for the project. First, to assess the methane emissions from shipping. To achieve this, the GREEN RAY project will combine existing data collection with onboard measurements to address existing vessels and new builds, normal operation and varying loads, and further utilize these results in a model development to achieve LNG fleet level assessment. Moreover, these results are utilized in preventing the methane slip formation, which is the second main objective of the project.
To reduce methane slip, the GREEN RAY project will develop two on-engine technologies for low pressure dual fuel engines and an aftertreatment technology for the existing vessels as well as newbuilds. First, the four-stroke engine technology is developed further to enable methane slip reduction at all engine loads and to be applicable to the largest engines in the market involving cruise, ferry, and gas carriers. Second, the two-stroke engine development, around a patented LNG injection system, will aim to significantly reduce methane slip from e.g. tankers and container ships. Third, a unique approach of a sulphur resistant catalyst system is aiming to significant methane oxidation while also ensuring that the activity remains high over time. The achievements of these three technologies' development will be demonstrated onboard one new build and two retrofits to existing vessels, all of them targeting TRL 7.
Adapting the technologies developed in GREEN RAY makes it possible to achieve up to over 20% GHG benefit for LNG engines compared to oil-based engines. This is possible since the successful demonstration of technologies is expected to result in 40-90% methane slip reduction. Furthermore, all technologies are also developed to be capable of being utilized with bio- or synthetic gas instead of fossil LNG, maximizing the benefits for climate.
There are two main objectives for the project. First, to assess the methane emissions from shipping. To achieve this, the GREEN RAY project will combine existing data collection with onboard measurements to address existing vessels and new builds, normal operation and varying loads, and further utilize these results in a model development to achieve LNG fleet level assessment. Moreover, these results are utilized in preventing the methane slip formation, which is the second main objective of the project.
To reduce methane slip, the GREEN RAY project will develop two on-engine technologies for low pressure dual fuel engines and an aftertreatment technology for the existing vessels as well as newbuilds. First, the four-stroke engine technology is developed further to enable methane slip reduction at all engine loads and to be applicable to the largest engines in the market involving cruise, ferry, and gas carriers. Second, the two-stroke engine development, around a patented LNG injection system, will aim to significantly reduce methane slip from e.g. tankers and container ships. Third, a unique approach of a sulphur resistant catalyst system is aiming to significant methane oxidation while also ensuring that the activity remains high over time. The achievements of these three technologies' development will be demonstrated onboard one new build and two retrofits to existing vessels, all of them targeting TRL 7.
Adapting the technologies developed in GREEN RAY makes it possible to achieve up to over 20% GHG benefit for LNG engines compared to oil-based engines. This is possible since the successful demonstration of technologies is expected to result in 40-90% methane slip reduction. Furthermore, all technologies are also developed to be capable of being utilized with bio- or synthetic gas instead of fossil LNG, maximizing the benefits for climate.
During the second reporting period, we have studied the methane slip and other emissions from a newbuild cruise ship. In addition, the actual methane slip measurement with different devices has been investigated. Methane slip from LNG dual-fuel engines varies with engine load and pilot fuel share. A regression model capturing these effects has been developed and integrated into Ship Traffic Emission Assessment Model (STEAM). The updated emission factors for CO2, CO, NOₓ, CH₄, and HCOH have been calculated. The new STEAM version 5 also includes improved modeling of weather effects and fuel consumption for LNG-powered diesel-electric ships, with ongoing refinements based on GREEN RAY project results.
The development of the 2S engine focuses on pioneering a novel system for injecting cryogenic LNG fuel (below 0°C) into 2S marine engines. This technology aims to replace existing gas admission valves and rails on DF engines with a new cryogenic gas valve and LNG rail. To support this, a dedicated fuel supply and pumping system was developed and installed in the laboratory. For performance benchmarking, an initial test was conducted using an LNG medium-pressure injection system, evaluating both stratified lean-charge pre-mixed "Otto" combustion and diffusive "diesel-like" combustion.
The success story of the Wärtsilä 31 NextDF continues through the development of W46TS NextDF in the project GREEN RAY. The performance concept was defined and simulated, a full-scale prototype engine designed, constructed and successfully validated in Wärtsilä’s engine laboratory in Vaasa, Finland.
During the 2nd reporting period, the methane oxidation catalyst (MOC) has been been successfully scaled up so it can be manufactured for on-engine demonstration. In the 1st phase 7.5x4.7in parts were produced and they are currently being tested at Wärtsilä. In the 2nd phase 34 parts of the 12x5 parts were manufactured for full scale demonstration on board of ship. These parts are also canned and ready for installation. Upstream of the MOC, a sulphur guard bed (SGB) catalyst has been optimized to provide the maximum protection for the MOC given the 16,000hrs of operation before a change out. This formulation has been scaled up and over 2 metric Tonnes of material were produced for the full demonstration. Shell also manufactured and filled the modules that hold the SGB catalyst. They are currently ready for deployment once a field demonstration is identified.
During this second reporting period, one new generation four-stroke engine has been delivered in a cruise vessel under construction to be delivered in 2026. The methane oxidation catalyst system will be added at the outlet of a four-stroke engine in an existing vessel in 2025 or 2026. The two-stroke engine technology development has faced some challenges and therefore the onboard demo has not yet proceeded as planned.
The development of the 2S engine focuses on pioneering a novel system for injecting cryogenic LNG fuel (below 0°C) into 2S marine engines. This technology aims to replace existing gas admission valves and rails on DF engines with a new cryogenic gas valve and LNG rail. To support this, a dedicated fuel supply and pumping system was developed and installed in the laboratory. For performance benchmarking, an initial test was conducted using an LNG medium-pressure injection system, evaluating both stratified lean-charge pre-mixed "Otto" combustion and diffusive "diesel-like" combustion.
The success story of the Wärtsilä 31 NextDF continues through the development of W46TS NextDF in the project GREEN RAY. The performance concept was defined and simulated, a full-scale prototype engine designed, constructed and successfully validated in Wärtsilä’s engine laboratory in Vaasa, Finland.
During the 2nd reporting period, the methane oxidation catalyst (MOC) has been been successfully scaled up so it can be manufactured for on-engine demonstration. In the 1st phase 7.5x4.7in parts were produced and they are currently being tested at Wärtsilä. In the 2nd phase 34 parts of the 12x5 parts were manufactured for full scale demonstration on board of ship. These parts are also canned and ready for installation. Upstream of the MOC, a sulphur guard bed (SGB) catalyst has been optimized to provide the maximum protection for the MOC given the 16,000hrs of operation before a change out. This formulation has been scaled up and over 2 metric Tonnes of material were produced for the full demonstration. Shell also manufactured and filled the modules that hold the SGB catalyst. They are currently ready for deployment once a field demonstration is identified.
During this second reporting period, one new generation four-stroke engine has been delivered in a cruise vessel under construction to be delivered in 2026. The methane oxidation catalyst system will be added at the outlet of a four-stroke engine in an existing vessel in 2025 or 2026. The two-stroke engine technology development has faced some challenges and therefore the onboard demo has not yet proceeded as planned.
Results from the experiments done onboard a modern cruise ship during real operation show that the weighted specific emission for methane is 2,8 g/kWh or 1,7 % of fuel . This is significantly lower than the default value applied in the FuelEU Maritime regulation which is 3,1 % of fuel. This already gives an indication that the engine technology development is on the right track in addressing the methane slip emissions while the GREEN RAY project is expected to significantly improve this addressing also e.g. the lower load conditions.
Results from the initial test on the 2S engine with cryogenic LNG injection indicate a notable reduction in methane slip compared to conventional injection methods. By utilizing cryogenic injection it is possible to create a better fuel stratification inside the combustion chamber, improving combustion efficiency and reducing unburned methane emissions.
The methane slip reduction for the 4-stroke engine was demonstrated in the Wärtsilä’s Sustainable Technology Hub in Vaasa, Finland, well exceeding the GREEN RAY target. The methane slip is now on a flat 1,1% of fuel consumption in a wide operating area, staying below 1,4% in all load points.
Results from MAC system in engine lab tests at the Wärtsilä facilities in Vaasa show good thermal stability and high methane conversations using real engine exhaust flows from several different Wärtsilä DF as well as single gas engines.
Results from the initial test on the 2S engine with cryogenic LNG injection indicate a notable reduction in methane slip compared to conventional injection methods. By utilizing cryogenic injection it is possible to create a better fuel stratification inside the combustion chamber, improving combustion efficiency and reducing unburned methane emissions.
The methane slip reduction for the 4-stroke engine was demonstrated in the Wärtsilä’s Sustainable Technology Hub in Vaasa, Finland, well exceeding the GREEN RAY target. The methane slip is now on a flat 1,1% of fuel consumption in a wide operating area, staying below 1,4% in all load points.
Results from MAC system in engine lab tests at the Wärtsilä facilities in Vaasa show good thermal stability and high methane conversations using real engine exhaust flows from several different Wärtsilä DF as well as single gas engines.