Transport and carbon dioxide emission: the Brazilian case

摘要

The transport sector is one of the main contributors to the carbon dioxide (CO_2) emissions, being practically the only one in which the consumption of fossil fuel by-products has increased since the first oil crisis. Since the early 90' leaders of the world governments have been discussing over a way of reducing the greenhouse gases emissions of anthropogenic sources, particularly CO_2 emissions from fossil fuels burning. In Brazil, the transport sector is responsible for 21% of the total energy consumption in the country, which in 2000 was of 46.43 millions of toe (tonnes of oil equivalent) (1toe = 10.800 Mcal), including all the primary energy sources, not excluding the hydroelectricity. In relation to the consumption of oil by products, such sector is responsible for about 59% and is equivalent to 3.2 times the consumption noted in the industrial sector. We can verify that 88.1 % of the consumed energy originates from oil sources - diesel oil, fuel oil, gasoline, jet fuel and kerosene. Ethanol represents 10.3% of total fuel consumed in transportation, in hydrated or anhydrous form. In this connection, the use of ethanol in Brazil for the transport sector may prove to be an important alternative furthering the efforts to stabilize the actual level of greenhouse gases in the atmosphere. The energy derived from biomass, and in this case, from a renewable, "clean" source, i.e., from sugar-cane, has the unquestionable advantage of permitting the almost complete reabsorption of CO_2 emitted through the combustion of fuel alcohol. This closed cycle allows, in principle, to increase the energy supply, essential for economic development, with fewer hazards to the environment. In spite of the doubts around the greenhouse effect issue, the consequences that may arise of it represent a great risk that should be considered in the planning of the intensive sectors such transport.