Wärtsilä 2-Stroke Dual-Fuel: A Single Solution

There is a growing awareness in today’s marine market of the need for alternative fuel solutions that can reduce emissions while also demonstrating commercial viability. Finding a single solution that can ensure compliance with impending regulations to reduce sulphur oxide (SOx), nitrogen oxide (NOx) has so far proven to be elusive however.

In meeting compliance criteria with Tier III NOx regulations from 2016 and the introduction of 0.1% SOx limits in North American and European Emission Control Areas (ECA’s) in 2015, conventional thinking has maintained that a single solution for both NOx and SOx emission would be a perfect choice. Wärtsilä’s dual-fuel low-pressure gas engines have demonstrated that there is no requirement for the installation of additional equipment, such as exhaust gas after treatment (catalytic reduction and sulphur scrubbers), to meet Tier III NOx regulations while running on gas.

Moreover, for vessels operating in ECA’s, Wärtsilä dual-fuel solutions offer an alternative to more costly distillate fuel allowing the vessel operator to switch fuel to gas. With marine gasoil prices currently at 50 per cent more than high sulphur bunker fuel, dual-fuel engines offer ship operators an alternative solution to costly bunker fuel bills while fulfilling the emission regulations.
Dual-fuel engine installations offer the flexibility much sought after by operators, allowing them to switch between gas and residual or distillate fuels, depending upon price and bunkering availability. Despite the infancy of LNG bunkering, its longer term potential is becoming increasingly clear. As a result, the ongoing development of the LNG bunkering infrastructure will support organic growth until the use of LNG as a fuel becomes widespread practise, early signs of which are being illustrated in the shape of new LNG bunkering stations being developed in northern Europe.
Natural gas is the alternative fuel offering the greatest potential considering the upcoming environmental regulations. Wärtsilä has exceeded six million running hours in both land-based and marine applications with medium speed dual fuel engines and is the leading supplier of dual-fuel engines to the LNG carriers market since 2005.
In late 2010, Wärtsilä initiated a major project to extend its leadership for dual-fuel engines by adapting the low pressure gas engine technology to low-speed engine portfolio. A new test engine named ‘RTX-5‘ (based on a commercially available 6-cylinder RT-flex50 engine) was installed in the Trieste engine laboratory in Italy in March 2011. It has been demonstrated successfully for the first time that low-speed engine performance can fully comply with IMO Tier III nitrogen oxide (NOx) limits while the low pressure 2-stroke dual-fuel engine is operating on gas. Wärtsilä’s low pressure 2-stroke gas engine will be available for on-schedule commercial use in 2014.

Information source: Wärtsilä article October 2012; Producer: Mirja-Maija Santala, Media Manager, Wärtsilä Corporation.