Experience with Low NOx conversions by Wärtsilä NSD Corporation of the marine diesel engines in two Norwegian ferries has demonstrated that such investment is highly worthwhile in cutting exhaust-gas emissions and thereby making vessels yet more environmentally friendly.

Late in1999, the ferry owner Bastø Fosen upgraded the main engines onboard their ferries "Bastø I" and "Bastø II" with Low NOx technology to reduce their exhaust emissions. Each ferry is equipped with a single Wärtsilä Wichmann 12V28B medium-speed, two-stroke main engine, developing 3960 kW at 660 rev/min. The modifications have been very successful. Apart from achieving lower emissions, the upgrading has reduced fuel consumption and the engines can run at full power according to expectations. Each engine has since operated for more than 3000 hours.

Low NOx technology was developed by Wärtsilä NSD Corporation as a way of adapting diesel engines to achieve significant reductions in both nitrogen oxides (NOx) emissions and specific fuel oil consumption. The improved fuel efficiency also leads to reduced emissions of carbon dioxide (CO2), as well as lower operating costs. Low NOx technology is engine based. It does not involve investment in additional equipment, or higher costs for extra maintenance work, chemicals or water additives.

Wärtsilä NSD focused on optimisation of the fuel injection system, combustion chamber and the turbocharging system to create the right conditions for lower NOx emissions. The result of this development programme is that the company can now offer complete Low NOx upgrading packages for all Wärtsilä Wichmann engines produced since the beginning of the 1970s. So far, the engines of about 30 vessels have been successfully upgraded using this engine-based Low NOx technology.