Exhaust emissions of transit buses: Brazil and India case studies

In order to aid fleet fuel choices, specifically in Brazil and India, this report compiles emissions testing data from in-use or real world drive cycle tests. The data is used to compare the range of emissions for four emissions that are commonly regulated by emissions standards (CO, THC, NOx, PM) and CO2 emissions. The combined results of the analysis show some of the best performing fuel options in Brazil and India are 20% blend Biodiesel with Diesel Particular Filter and Selective Catalytic Reduction (B20 + DPF + SCR) and Compressed Natural Gas with Three Way Catalyst (CNG + 3WC). However, other fuel or technology options provide meaningful results - CNG fuels or Hybrid buses can provide significant PM reductions or CO2 reductions, respectively. For fleet decisions, further aspects of the local context should be considered as well, such as the impact of maintenance practices, altitude, and local driving cycles on emissions when making vehicle decisions. Also, the usual practice of covering the capital costs out of user fares may not be applicable for the introduction of cleaner buses; the use of national and international funds may be applicable, as the cleaner technologies help achieve energy consumption or emissions reduction targets.