Emissions – what do I need to know?

Wärtsilä works on the reduction of emissions

The new regulations for emissions are flying fast and furious: everywhere, you hear such terms as CO2, methane, NOx, particulates. But what do these concepts mean? What is NOx? What is SOx? What do we need to take account of in shipping? And how can Wärtsilä help with this?

Scroll down for our answers ↓

“Roughly speaking, you can make a distinction between two categories of emissions: local emissions and greenhouse gases”, says Sebastiaan Bleuanus, general manager of Research Coordination & Funding Portfolio, Technology Strategy & Innovation at Wärtsilä.

'Local emissions cause short-term problems at the location. For example, nitrogen oxides and sulphur oxides, also referred to as NOx and SOx, along with particulates, have an immediate effect on human health at the location.

“The second category consists of greenhouse gases such as carbon dioxide and methane, or CO2 and CH4. These types of emissions results in worldwide problems in the longer term, such as climate change due to global warming, including the extreme storms of recent years. The distinction between the two categories is not as clearly delineated as I'm sketching here. For example, small particles in the air can delay the heating of the Earth, since solar radiation reflects off the dust. But locally, the same particles result in health problems.”


  • NOx (nitrogen oxides): cause smog and health problems and result in the acidification and over-fertilisation of the natural environment.
  • SOx (sulphur oxides): cause acid rain and encourage the formation of particulates.
  • Particulates: the air pollution that contributes to the development of lung cancer and other health problems.


  • CO2 (carbon dioxide): is part of the cause of global warming.
  • CH4 (methane): is part of the cause of global warming. On balance, it does 28 times as much damage as CO2, but it is much less present in terms of absolute volume.

Fill out the form to download the presentation 'Emissions and Wärtsilä Engines'.

Humans and emissions

Most emissions are caused by human activities such as burning fuel, large-scale livestock farming, deforestation, etc. Sebastiaan: “The emissions are an absolute fact. The question is: how do we respond to this. There are various options. We could combat the symptoms, for example, by planting rice instead of potatoes as a response to the heavy rains. But it's preferable to tackle the emissions problem at the source. After all, the effects of the emissions are unfairly distributed: poor people pay the price far more than rich people.”

Shipping and emissions

Around 3% of all greenhouse gas emissions are caused by shipping. This is equivalent to the total emissions of a large country such as Germany. Without new regulations, those emissions would grow between 200% and 250% between 2008 and 2050. Sebastiaan: “Other sectors are working hard on decreasing their emissions. So imagine if the shipping sector were not to change. Then that 3% share would increase to somewhere between 6% and 10%.”

Something has to happen

For this reason, Wärtsilä tries to decrease the environmental impact of its engines. “For example, our engines already emit 85% less methane than in 1993 and our large engines fuelled by natural gas emit 12% to 30% less greenhouse gas than comparable HFO or LFO diesel engines.”

Electrical power?

“For the time being, sailing on batteries is not the primary solution for long distances”, says Sebastiaan. “Under certain conditions and for short distances, this may be so. For example, we can already have a ferry sail for up to 30 minutes. We enable this by means of wireless charging and auto-docking technology. Inland waterway shipping could also use batteries for propulsion. But to get a container ship from Shanghai to Rotterdam you would need a couple billion batteries. And once you've reached port, you would still need two weeks to recharge or to exchange all those batteries. The technology is indeed advancing, but not so quickly that batteries will already present the solution in 2030.”

What about gas?

Gas can serve as a transition fuel. The primary component of LNG is methane – so whether it comes from under the ground or from biomass, this makes no difference to the application. Sailing on gas contributes to decreased emissions of greenhouse gases since the small quantity of methane emissions pales by comparison with the reduction of the CO2 emissions as compared to traditional fuels. Furthermore, there is practically no SOx emission; and gas emits 90% less NOx and particulates than diesel, so local air quality improves enormously. Sailing on gas nonetheless requires investments in infrastructure, and gas is not available everywhere. Sebastiaan: “Is gas the only solution? No. Is gas a good solution? Yes!” Bram Kruyt, Director of Inland Waterway Shipping at Wärtsilä, about our Dual Fuel engines and LNGPac

Electrical or hybrid?

Wärtsilä develops hyper-modern gas and duel-fuel engines, but also looks beyond simply that engine. Sebastiaan: “We're constantly thinking up intelligent solutions based on the latest technologies, in which we optimise the ship in its entirety. We recently opened the Wärtsilä Hybrid Centre for this in Italy. Consider electrical or hybrid propulsion, for example, and exhaust gas scrubbing systems. This way, we arrive at solutions that are independent of this segment and application. The key word here is system integration, in which efficiency is leading: achieving objectives for the lowest total cost. This is better for our customers and better for society.”

Sailing more efficiently and reducing emissions step-by-step:


Lower the ship's energy needs. Take away whatever you don't need. Improve the shape of the hull. Hoist a sail, etc.


Choose engines with a higher level of efficiency. (Fun fact: Wärtsilä has the most efficient diesel engine in the world.)


Use transitional fuel wherever possible, fuel that has as little environmental impact as possible.



Sebastiaan Bleuanus

general manager of Research Coordination & Funding Portfolio, Technology Strategy & Innovation at Wärtsilä.