The use of Liquefied Natural Gas (LNG) in transport is a suitable option to power large long-distance trucks in areas where gas is transported as liquefied natural gas because there are indigenous gas supplies and no gas network. The use of LNG in passenger cars is far less viable because on average passenger cars stand idle more often, which would give rise to high evaporative losses.

Employing regenerative braking in trains can lead to substantial CO₂ emission reductions, especially when applied to full stop service commuter trains (8 – 17%) and to very dense suburban network trains (~ 30%). Regenerative braking applied to freight trains can also lead to CO₂ emission reductions, albeit considerably lower than for full stop service trains (~5%). When regenerative braking is employed, the current in the electric motors is reversed, slowing down the train.

Fuel cells are used to produce electricity. They are considered a promising technology to replace conventional combustion engines in vehicles. Fuel cells may also replace batteries in portable electronic equipment. The most widely used types of fuel cells for mobile devices are Proton Exchange Membrane fuel cells (PEM FC) which are often used in vehicles, and Direct Methanol fuel cells, used in portable applications. PEM fuel cells use hydrogen or certain alcohols such as methanol as fuel.

Advanced bio-hydrocarbons are second generation biofuels and are derived from lignocellulosic biomass such as trees, grasses, waste, agricultural or forest residues, or algae. These fuels are not produced using the agricultural commodities like corn, sugarcane, soybean, etc.

The use of Compressed Natural Gas (CNG) as a transport fuel is a mature technology and widely used in parts of the world. Although compressed natural gas is a fossil fuel, it is the cleanest burning fuel at the moment in terms of NO_x and soot (PM) emissions.

Electric vehicles are about 2.5 times more energy efficient than their counterparts which are powered solely by internal combustion engines. This high energy efficiency is the main reason why electric vehicles can contribute to lower the CO2 emission and energy consumption of traffic substantially. Electric vehicles have zero tailpipe exhaust emissions and thus contribute substantially to a better air quality. Additionally, electric vehicles are inherently silent and can help to reduce the noise levels in cities.

Electric motors are widely used in various sectors where mechanical energy is needed. It is an electromechanical device which converts electrical energy into rotary mechanical energy. This output is then further converted to provide the needed final use-­‐energy. The two main components of motor are the stator (stationary element) and the rotor (rotating element).

One approach to lowering the CO₂ emission from traffic is the hybridization of vehicles. A hybrid vehicle uses two or more distinct power sources, i.e. hybrid electric vehicles (HEVs) combine an internal combustion engine and one or more electric motors. Vehicles employed in urban areas like small passenger cars, local delivery trucks and city busses benefit from hybridization and show substantially lower CO₂ emissions, ranging from 23 to 43% depending on the traffic dynamics.

Liquid biofuels for transport, including biodiesel, have to a certain extent been in use for a very long time. In recent years however, they are enjoying renewed interest in both developed and developing countries as a result of the need to curb rising emissions from the transport sector, reduce dependence on expensive fossil oil imports and increase farm incomes.

A plug in hybrid electric vehicle (PHEV) is a hybrid electric vehicle with the ability to recharge its energy storage with electricity from an off-board power source such as a grid. PHEVs have the potential to displace a significant amount of fuel in the next 10 to 20 years. It is estimated that they can reduce fuel consumption by up to 45% relative to that of a comparable combustion engine vehicle.