Critical Review of Trends in GHG Emissions from Global Automotive Sector

Between 1906 and 2005, records show that global average air temperature near the earth’s surface increased by 0.74 ± 0.18°C. If emissions of greenhouse gases, and in particular CO2, continue unabated the enhanced greenhouse effect may alter the world’s climate system irreversibly. Total emissions of greenhouse gases, across all sectors, were 42.4 gigatonnes (Gt) of CO2-eq in 2005. Energy sector, accounts for 84% of global CO2 emissions and 64% of the world’s greenhouse-gas emissions. Energy-related CO2 emissions rise from 28.8 Gt in 2007 to 34.5 Gt in 2020 and 40.2 Gt in 2030. Global per-capita emissions of energy-related CO2 in 2007 was 4.4 tonnes. Higher growth of automobiles and consumption of petroleum products is invariably attended by concerns of pollution and climate changes. Global fleet of passenger light-duty vehicles (PLDVs) is estimated to increase from 770 million in 2007 to 1.4 billion in 2030. Among all sectors that emit CO2, the transport sector is the fastest growing, representing from 22% to 24% of global GHG emissions from fossil fuel sources, second only to the industrial sector. World emissions of NOx were 82 Mt in 2007, of which Road transport was responsible for about one-third of NOx emissions. Only Road transport related CO2 emission is estimated to increase from 4.8 Gt in 2007 to 6.9 Gt in 2030. The increase in CO2 emissions is largely a result of increasing demand for individual mobility in developing countries. There are strong efforts and renewed investments by manufacturers and suppliers in providing solutions to the CO2 reduction challenge. Low-carbon vehicles, such as hybrid cars, plug-in hybrids and electric cars, have received widespread public attention recently. It is estimated that share of hybrids in the global fleet will reach about 5% by 2020 and almost 8% by 2030, up from just 0.15% in 2007. Plug-in hybrids and electric cars will constitute only 0.2% of the global fleet in 2030. But increase in electricity consumption in road transport in future due to increased penetration of plug-in hybrids and electric vehicles, sees transport sector CO2 savings partially offset by power generation emissions. An estimated increase of 880 TWh of electricity consumption in transport in 2030, of which 90% occurs in PLDVs, will result in about 250 Mt of additional CO2 emissions. Authors forecasted that the use of environment-friendly and clean technologies is going to make all the difference between the winners and the losers of the industry. It is noted that current policies are insufficient to prevent a rapid increase in the concentration of greenhouse gases in the atmosphere. It is recommended that policy makers and researchers should give more emphasis on ‘cost-effectiveness as most important factor to reduce automotive GHG emission reduction’. It is also concluded that CO2 savings will be maximized if well-to-wheel impact is clearly addressed at all stages of the fuel and energy chain.