Being Tier III compliant today
Sustainability assured 2011Wärtsilä focuses on the development of environmentally sound solutions that are cost-efficient, reliable, and compliant with the requirements of the International Maritime Organisation. The forthcoming IMO Tier III nitrogen oxides emission limits require new solutions in shipping.
The IMO Tier II NOx emission levels have recently come into force, and Wärtsilä's development work is now focused on the Tier III requirements. The Tier III emissions levels will be applied from 2016, which may seem to be still a long way off. Wärtsilä has, however, already developed technologies that allow operations to be TIER III compliant today.
Wärtsilä NOx Reducer (NOR)
Wärtsilä is currently able to offer a Tier III compliant solution based on Selective Catalytic Reduction (SCR) technology. SCR technology has already been available for some years, mainly for use in power plants. However, in order to introduce SCR for marine installations, engine technology development work has been necessary since the optimum exhaust gas temperature range for SCR is narrow. To achieve optimal engine tuning in combination with SCR, an intelligent control system and variable valve train are required. This technology has been developed and validated, and it is available as standard on all Wärtsilä 4-stroke engines. Thus, with a properly designed and controlled SCR solution, compliance with the Tier III requirements can be achieved – even when using HFO together with a scrubber.
LNG as a fuel enables Tier III NOx emission requirements to be met. Pre-mixing of the fuel with air enables combustion with low emissions. Our 4-stroke engine portfolio now includes the new W20DF engine, the latest dual-fuel engine to be introduced to the market. To have LNG as a fuel for 2-stroke engines without compromising energy output or efficiency has, however, always been considered extremely challenging. In order to meet the strong market need for a 2-stroke low pressure gas engine, Wärtsilä has begun the development of a 2-stroke gas engine. Technologies used to control combustion in 4-stroke engines, while avoiding knocking and misfiring, cannot be used directly on a 2-stroke engine. Nevertheless, Wärtsilä’s vast experience in gas engine development, together with new innovations, has resulted in a technology that has enabled Wärtsilä to successfully perform engine testing on a 2-stroke gas engine capable of complying with Tier III emission levels. The first installation is planned for 2013.
Exhaust Gas Recirculation
Distillate fuels, meaning both heavy fuel oil (HFO) and light fuel oil (LFO), will remain as the main marine fuels for the foreseeable future. The need for lifecycle optimised products is high. Investment costs need to be minimised, engine efficiency should be significantly improved and NOx emissions must become dramatically lower than what the industry is used to. In order to combine and meet all these requirements, new technologies must be developed and adopted in a cost effective way. The next generation of Wärtsilä’s products will be Tier III compliant without the need for separate after-treatment equipment. There is no obvious single solution for meeting the Tier III emission requirements, as several technologies are still under evaluation. The basic challenge for shipping is that there will be two areas with different emission standards, and much of the world’s fleet will operate in both. As there is no standardised fuel, the technical solution needs to be different from the one currently used in cars and trucks. The technologies currently being evaluated include 2-stage turbo charging in combination with EGR (exhaust gas recirculation) and/or engine integrated SCR.
The different emissions technologies must be capable of being adapted to the current engine platforms. The first installation fulfilling the Tier III emission requirements using only engine technology is foreseen in 2014.