Chapter 9: Fuel Options

Transport is an essential human activity and it has played an important role in the development of many societies. However, the environmental costs of this energy-intensive sector are also critical: e.g. it produces 20% of all anthropogenic greenhouse gas emissions. While all modes of transport have an environmental impact, the major impact is from road transport. Since the early part of the twentieth century the primary automotive fuels have been gasoline and diesel; however, a few countries such as Brazil, Italy, and New Zealand have developed a vehicle transportation system based on alternative fuels (AFs).

Fuel composition and characteristics play an important role in emissions, and standards for gasoline and diesel were established to ensure that they meet minimum requirements. Changes in one fuel characteristics may lower emissions of one pollutant but increase those of another. For example, a decrease in the aromatic content of gasoline may lower carbon monoxide (CO) and hydrocarbon (HC) emissions but may increase nitrogen oxide (NO_x) emissions. However, a major advantage of fuel modification is that it often can take effect quickly and begin reducing pollutant emissions immediately.