ABSTRACT
On a worldwide scale, 26% of primary energy is consumed for transport purposes, and 23% of greenhouse gas emissions is energy-related. Street traffic represents a share of 74% in the transport sector worldwide (IPCC data from 2007, as summarized in [1]). The transport sector includes aircraft, ships, trains, and all types of street vehicles (e.g., trucks, buses, cars and two-wheelers). Automobiles play a particular role for three reasons: First, cars are dominating the street traffic in most countries. Second, car sales exhibit the greatest growth rates in the world. Third, there are alternative technologies for the drivetrain available unlike, e.g., for trucks. While small trucks may also be operated electrically within a limited range, big trucks are dependent on diesel fuel, which can be shifted to a mixture of 80% methane (either fossil or biogenic) in the
future. Buses can also be driven electrically on limited distances; buses driven by compressed natural gas (methane) are routinely used. While fuel cell-driven buses are already on the streets, small trucks driven by fuel cells and H2 are still concepts.
