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.
