Vehicles with External Energy Supply Such vehicles do not carry their internal energy source. Usually the energy is delivered from a stationary facility. There are different principles used to deliver different forms of energy to the vehicle like: • Electric energy can be delivered using power lines or electrified rails (e.g. at trains, subways, streetcars, power line busses). • Electric energy might be delivered using microwave transmission (future applications might be airplanes and electric propelled rockets/satellites). • Mechanical energy can be delivered using transmission strings (cable cars, cable boats). • Mechanical energy can be delivered by magnetic fields (e.g. for future magnetic levitation subways and trains). The conversion process at the above vehicles will not be discussed in further detail because they use already secondary energy as input. The conversion therefore is dealt with in the section Electricity Production. Variations in the market shares of vehicles with external power source influence the overall energy structure. Since these vehicles are primarily used in public transportation, the development of the market shares in public transportation (versus individual transportation) is an essential figure. This figure therefore has influence on the form of energy used and on the amount of energy. For the time being, the development of market shares is different in different geographic areas. Generally the market share in urban areas of industrialized countries is rising, whereas it is dropping in threshold countries and remains on its current level in developing countries. Vehicles with Direct Conversion These vehicles do not have an energy storage system because they transfer energy collected from outside (= external energy) into the required kinetic energy. Since nowadays market share is limited and does not seem to increase significantly in future, only a short description of wind and solar energy use will be given. Wind powered vehicles have a long tradition. Examples are sailing boats, balloons and gliders. For about 30 years there have been research projects to develop big wind powered freight ships (based on the Magnus effect). Also research projects deal with new forms of application of wind gradients for freight airplanes (albatross flight). Solar powered vehicles usually use solar cells to generate electric power from sunlight. Typical applications are solar powered cars, boats, satellites and airplanes. Since solar powered cars, usually can not be operated without sunlight it appears to be more a sports toy (electric powered cars will be described later). For airplanes that have to stay for a long time at a high altitude (e.g., for broadcasting and for remote sensing) solar power supply is an interesting option. It is also possible to convert the photons' impulse directly into the propelling force or to use the solar wind in space. Due to limited application, these options will not be discussed further. Vehicles with their Own Internal Energy Storage This section describes the most common present transportation systems. As mentioned before the most important features of the energy storage systems are their weight and volume. Also the recharging (or refueling) process should be easy and fast. The vehicles' energy sources are subdivided here into chemical, electrical and nuclear. Chemical storage is mostly done by liquid fuel. Cars for individual transportation contribute most to the overall traffic use. Nowadays they are usually propelled by petrol (and sometimes diesel). Petrol has a high energy content, is (in case of an accident) relatively safe and is easy to handle. Also the petrol distribution system is very well developed. The engine technology is well developed and is usually based on a combustion process inside a cylinder. A moveable piston is transferring the combustion process energy into mechanical energy. Since many dynamic processes take place simultaneously inside the cylinder, not all performance parameters of the engine can be optimized independently. This is especially a problem in terms of the reduction of the various exhaust gases. This makes the environmental issue quite challenging (especially in urban areas). In many industrialized countries there is therefore a strong political
RkJQdWJsaXNoZXIy MTU5NjU0Mg==