Unregulated Emissions from Heavy-Duty Engines and Vehicles

Sammanfattning: Road transport emission levels are at an all-time low and post Euro VI regulations are now up for discussion. A literature study of unregulated diesel emissions in Europe; CO2, N2O, NO2, CH4 and aldehydes has been made to determine the effects and importance of the emissions in today´s heavy-duty vehicles. This work aims to give better knowledge of the emissions with fundamental information about each emission’s formation, environmental effects, health effects, measuring methods, and reduction methods. Also examined is the possibility of limiting these emissions and what policies can be enforced in any future legislative directives. The greenhouse gas emissions, CO2, N2O and CH4, from road transport are getting a lot of attention since they are hugely responsible for an increase of the global temperature. CO2 will clearly be the focus of future regulations. It is the most abundant emission and is the main cause of global warming. Reduction is best achieved through more fuel efficient vehicles but regulations and political means will also be needed to lower CO2 levels in the atmosphere. The European Commission have therefore agreed in 2014 to come up with a plan to cut their CO2 emissions from road transport. The most important ozone depleting substance today and the most potent of the greenhouse gases is N2O which has a GWP of 298. It is mainly produced by aftertreatment systems and its formation is highly dependent on temperature. CH4 is a regulated emission for CNG but not for diesel where the levels are much lower. It has a GWP of 34 and is plays a big role in global warming. Although it is an important emission to examine, the levels of CH4 from diesel vehicles today are negligible. In modern diesel vehicles NO2 emissions come from platinum catalysed DOCs and DPFs. NO2 is used for DPF regeneration and causes respiratory problems as well as contributing heavily to ozone formation and smog pollution. By adopting a better urea dosing strategy and choosing DPF coating material with less platinum NO2 can be reduced. Aldehydes are found in low concentrations in diesel but more in alternative fuels such as ethanol, and are important to study because of their carcinogenic properties and large contribution smog pollution. Studies have shown that the most abundant forms of aldehydes are formaldehyde and acetaldehyde for almost all fuel types, and that they can be reduced with efficient catalysts and high quality fuel. Different measurement techniques are used to analyse each of these mentioned emissions but their low levels require more accurate instruments with greater level of detail for measuring the substances.