Opportunity to reduce greenhouse gas by the use of alternative fuels and technologies in urban public transport in Brazil

In Brazil, urban public transport is carried out mainly by petroleum diesel buses which were responsible for the emission of 27.8 million tons of CO2 in 2010. In order to change this situation, new technological options are being researched (low carbon fuels and cleaner propulsion systems). This article aims to identify options of fuels and propulsion technologies which are applicable to bus transit in the state of Rio de Janeiro and which present a potential reduction in CO2 emissions in the short term. The use of biodiesel and diesel-gas systems stand out in relation to reductions in CO2 emission when one considers initial investment, energy consumption and operational cost. The use of hybrid-drive buses is a promising option. The use of bio-ethanol is expensive but it is shown to be the best option to reduce CO2 emissions. The same conclusion it is found to be not true for dedicated natural gas buses.