**5. Conclusions**

Atmosphere protection against pollution from seagoing vessels is currently one of the most important areas of ecological activity in maritime transport. Various solutions are implemented on ships that allow for a significant reduction of toxic compounds in the exhaust gas.

Among others, fuel modifications made possible a reduction of the emission of toxic components of exhaust gases from modern marine diesel engines. The test results show that for environmental reasons, mixtures of marine diesel oil and rape oil esters (MDO)/(RME) may be supplied to the marine engines.

The supply of the engine during the tests, the mixtures of marine diesel oil (MDO) and rape oil esters (RME), caused a clear drop in emissions of nitrogen oxides and carbon dioxide, particularly for a higher engine load.

There is a possibility of reducing the emission of NOx through changes of the fuel injection parameters. The effect of changes to the fuel injection advance angle of emission oxides of nitrogen (NOx) and carbon dioxide (CO2) was investigated in the test.

The decrease of the injection advance angle unambiguously makes the NOx content in exhaust gas lower. The investigations also revealed that the advance angles of fuel injection change and they have no significant impact on the change content of carbon dioxide (CO2) in exhaust gas.

The use of biofuels (a mixtures of marine diesel oil and rapeseed oil esters), or a reduction in the advance injection angle are the possible solutions to be used immediately, without significant investment costs.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
