New review article compiles the current knowledge related to the ship engine emissions

Recent study by VTT Technical Research Centre of Finland, Finnish Meteorological Institute, Tampere University along with several international experts compiled an in-depth review on how fuels and other technologies impact gaseous and particulate emissions of ship engines. The study also covered the best solutions to reduce emissions, their impacts to climate and health, simultaneously reaching the goal of zero-emission shipping.

“Based on the scientific literature, the impact of ship emission reductions can be maximized by aiming to reduce emissions’ climate, health, and environmental effects simultaneously and by emphasizing the technological solutions that fit into existing marine engines and infrastructure”, says Hilkka Timonen from Finnish Meteorological Institute.

Carbon-neutral fuels are often also less harmful to health

Several types of available fuels as well as option to reduce emissions by engine and aftertreatment technologies (e.g. catalyst, scrubber, filter) enable optimization of technological solutions for different ships, transportation routes and regions. This synthesis of the knowledge shows that, due to current and upcoming emission regulations and zero emission targets, there is high demand for carbon-neutral fuels, especially those resembling current fossil marine fuels, viz. compatible with proven technologies as “drop-in” fuels.

“Carbon-neutral fuels are typically also nearly sulphur free, which enables remarkable reduction of SOx emissions and the use of efficient exhaust aftertreatment technologies to reduce other harmful pollutants, such as particles”, says Topi Rönkkö from Tampere University.

It is seen that the emissions of exhaust compounds such as nitrogen oxides, sulphur oxides, ammonia, formaldehyde, and particulate pollutants, which are all harmful to health or the environment, need to be equally removed using the emission control achieved by fuel, engine or exhaust aftertreatment technologies.

Zero-emission shipping can be achieved with carbon-neutral fuels and efficient emission control technologies

Regarding particulate emissions, the emission reduction actions should be done so that they minimize the particle number and particulate mass emissions, taking especially into account the harmful compounds such as polyaromatic hydrocarbons, heavy metals, and black carbon (BC), which cause serious adverse health issues. In addition to impact on air quality, BC emissions from shipping have potential to accelerate global warming.

The combinations of carbon-neutral drop-in fuels and efficient emission control technologies would enable near zero-emission shipping and these could be adaptable in the short- to mid-term. Although substantial investments are needed to introduce these solutions, savings are gained with avoided external costs to society caused by the harmful emissions. "This gives arguments to create further support mechanisms and to invest in the clean technologies", says the leader of the study, Päivi Aakko-Saksa from VTT.

Further information:

Hilkka Timonen, Finnish Meteorological Institute, Hilkka.timonen@fmi.fi

Päivi Aakko-Saksa, VTT Technical Research Centre of Finland, Paivi.aakko-Saksa@vtt.fi

Topi Rönkkö, Tampere University, Topi.ronkko@tuni.fi

Scientific article is available on Progress in Energy and Combustion Science.

Reference:

Aakko-Saksa, P. T., Lehtoranta, K., Kuittinen, N., Järvinen, A., Jalkanen, J.-P., Johnson, K., Jung, H., Ntziachristos, L., Gagné, S., Takahashi, C., Karjalainen, P., Rönkkö, T., and Timonen, H.: Reduction in greenhouse gas and other emissions from ship engines: Current trends and future options, Progress in Energy and Combustion Science, 94, 101055, https://doi.org/10.1016/j.pecs.2022.101055, 2023.