Review of technologies for sustainable ground transportation

Currently there are nearly 750 million ground vehicles in service worldwide. They are responsible for 50% of petroleum (oil) consumption and 60% of all greenhouse gas (GHG) emissions worldwide. The number of vehicles is forecasted to double by 2050. Therefore the environmental issues such as noise, emissions and fuel burn have become important for energy and environmental sustainability. This paper provides an overview of specific energy and environmental issues related to ground transportation. The technologies related to reduction in energy requirements such as reducing the vehicle mass by using the high strength low weight materials and reducing the viscous drag by active flow control and smoothing the operational profile, and reducing the contact friction by special tire materials are discussed along with the portable energy sources for reducing the GHG emissions such as low carbon fuels (biofuels), Lithium-ion batteries with high energy density and stability, and fuel cells. The technological challenges and opportunities for innovations are discussed.