Magnetic levitation propulsion systems: technology, design, and applications

¶ … Magnetic Levitation Propulsion Systems in North America and Around the World

How Magnetic Levitation Propulsion System Works?

Development of the Maglev Technology

Design Differences in the German and Japanese Maglev Technology

Advantages of Maglev

Disadvantages

Cost Factor

Other Applications and spin-offs

Potential Projects in the U.S.A.

Magnetic Levitation Propulsion Systems

With air travel and the highways becoming increasingly congested, the need for an efficient, fast and comfortable mode of alternative travel has been felt in many countries of the world. One of the possible solutions is the Magnetic Levitation Propulsion System or high-speed trains called the Maglev train (short for magnetic levitation). The recent question mark over the safety of air travel and the fear of flying created among the general public by the events of 9/11 has renewed interest in the Maglev technology. In this paper we will discuss how the Magnetic Levitation Propulsion System works and briefly overview its history of development. The different types of designs developed so far, the cost of developing such systems, and the potential for its expansion and use in transportation systems in the United States and all over the world will also be discussed.

How Magnetic Levitation Propulsion System Works?

We all know that the opposite poles of a magnet attract while the like poles repel each other. This is the basic principle on which the Magnetic Levitation Propulsion System works. In magnetic propulsion systems, powerful electromagnets are used. The three basic components of a maglev train system are: A large electrical power source, metal coils that line the track or guide-way, and large magnets attached to the underside of the train. There is no conventional engine in maglev trains. Instead, the force for propulsion is achieved by a combination of the magnetic fields created by the electrified coils in the tracks (called the guideways) and the guideway walls.

When the magnetic coils lining the track or guideway repel the magnets attached to the underside of the train's carriageway, it makes the train levitate 1 to 10 cm above the track (the guideway). While the train is levitated, power is supplied to the coils in the guide-way walls that creates a system of magnetic field, providing a combination of 'pull' and 'push' forces to propel the train forward. Alternating current is supplied to the coils in the guideway walls that constantly changes the polarity of the magnetized walls. This causes the magnetic field in front of the train to exert a 'pulling' force on the train while the magnetic field at the back of the train 'pushes' the train forward adding more momentum to the forward thrust.

Development of the Maglev Technology

The concept of magnetically levitated trains is not new; it was first identified at the turn of the century by two Americans, Robert Goddard and Emile Bachelet. In the 1930s a German engineer (Hermann Kemper) further developed the concept. A patent was granted to Americans James R. Powell and Gordon T. Danby in 1968 for their design of such a train. After some years of serious research initially, interest and research in high speed Maglev technology was virtually halted in the U.S. In 1975 after the withdrawal of federal funding. However, in the past few decades, most effective research and development in Maglev technology has been carried out overseas -- notably in Germany and Japan. R & D. In Maglev technology started in earnest in Germany and Japan in the 1970s. In Japan the Railway Technical Research Institute (RTRI) has built and tested prototype Maglev trains on test tracks and attained speeds of over 400 km / hr. It is also engaged in the development of several key components of the Maglev train, e.g., the enhancement and reliability of the superconducting electromagnets (SCM) and special aerodynamic breaks.

The development and research in Germany has been equally promising and the development of the Transrapid system has recently attracted the attention of the Chinese who have chosen to install the system in its Shanghai City. This 20-mile link will connect the new Shanghai airport with its downtown business district that is due for completion in 2004. The Chinese have much more ambitious plans for the Maglev train as they propose to connect Shanghai with Beijing with an 800-mile connection if the Shanghai airport project is a success.

Faster Trips

For medium distances of up to 500 kms, the Maglev train technology would result in faster door-to-door trips. While most highways have speed limits and traffic congestion especially before entering and after exiting the highway, airports entail lengthy access and boarding times, and conventional trains are just too slow -- Maglevs are capable of high speeds (300 mph +) and have rapid acceleration and braking abilities.

Reliability

Maglev trains would be less susceptible to weather conditions -- the bane of air travel and even road and highway travel. Less than one-minute delays in schedules are possible, keeping in view the record of existing high speed trains in several countries.

Less Polluting

Being electrically powered Maglev trains would be less polluting than vehicles running on fossil-fuels since it is easier to mitigate pollution at the source of electricity generation, i.e., large electric power stations. It would also lessen dependence on imported fuel in countries which are deficient in fossil fuels but can generate electricity from indigenous sources.

Higher Capacity

Maglev trains would have the capability of higher capacities as compared to airlines and it has been estimated that they would be capable of transporting 12,000 passengers every hour in either direction. The potential capacity of Maglev trains is likely to cater for the required passenger traffic of the 21st century -- this cannot be catered for by the air and road infrastructure without dramatic expansion.

Comfort and Safety

Maglevs would provide greater comfort than air-travel due to roominess, and a smoother ride due to absence of air turbulence and frictionless motion due. The lack of physical contact between the train carriageway and the track results in substantial reduction in the noise level as well. Trains generally have high safety record and this is likely to apply to Maglev trains too.

Disadvantages

Despite its many advantages, the Maglev technology has its share of disadvantages too.

Incompatibility

Probably the biggest disadvantage of the Maglev technology is its complete incompatibility with the existing system -- train tracks for conventional trains etc. This results in the need for massive investment. (The cost factor will be discussed later in this paper).

Environmental Concerns

Some environmentalists have also expressed concern about the adverse health-effects of the magnetic fields, while supporters of the technology deny this.

Complex Operation and Instability at High Speeds

The technology is not yet fully proven. In the testing stage there have been reports of unstable operation at high speeds. Mitigation of the problem involves complex operation and maintenance solutions that are also expensive.

Cost Factor

In order to get an idea of the current costs for developing a Maglev system, it would be illuminating to examine the costs of the commercial project that is nearest to completion, i.e., the Shanghai Transrapid system. The Chinese government is paying $590 million to Transrapid for the supply of the equipment. It is spending about the same amount on building the infrastructure including stations, guideways, and the power system. This translates into a per mile cost of about 60 million dollars. Transrapid is of the view that this cost can be brought down to about $40 million per mile for a longer system. This is not cheap either, but the company contends that this cost is comparable to development costs of other transit links too, including highways.

Amtrak data shows that it costs up to $5 million per mile to upgrade rail track for conventional high-speed trains and about $10 to $20 million per mile to add a single lane to an existing interstate highway.

The costs of the Japanese design could be cheaper particularly if the effort for developing a better superconducting material (ideally a room-temperature super conductor) is successful.

Other Applications and spin-offs

Development of a commercially viable Magnetic Levitation Propulsion System is a state-of-the-art activity that has the potential of leading to a number of applications and spin-offs in other industries and products. Some of these are discussed below.

Magnetics

Development of high temperature superconducting materials being developed for magnets could find application in other industries such as cyrogenics, and low temperature refrigerators. The development of vibration insensitive magnets might be of use in transportable magnetic resonance imaging systems, military magneto-hydrodynamic systems for ship propulsion and other mobile applications.

Material

The use of nonconducting, nonmagnetic polymer reinforcing materials in concrete necessary for the guideways have the potential for extending the life of concrete structures. If successful, these materials will significantly reduce the life cycle cost when used in the renovation of highways and bridges.

Electrical Systems & Electronics

The development of higher power solid-state devices could have spin-offs for controlling motors in heavy industry, and linear synchronous motors for use in conveyors and manufacturing operations requiring precise control.

Engineering and Vehicle Design

Research in passenger comfort and environment requirements for Maglev trains also apply to other transportation modes too. These include research work in areas of minimizing environmental impacts from routing, magnetic exposure, noise, and air pollution. This has spin-offs in aerodynamics, noise mitigation and precision manufacturing.

Potential Projects in the U.S.A.

The following 7 Maglev projects have been proposed. However, these are in preliminary stages of approval and development and may take a decade or more before completion.

Pennsylvania. A 45-mile project linking Pittsburgh's airport with downtown Pittsburgh. The route eventually could extend to Philadelphia. Proposed by the Port Authority of Allegheny County.

Maryland. A 40-mile project linking Camden Yard in Baltimore and the Baltimore-Washington International Airport to Union Station in Washington, D.C. Proposed by Maryland Department of Transportation.

Nevada. A 42-mile project linking Las Vegas with Primm, Nev. Proposed by California-Nevada Super Speed Train Commission.

Florida. A 20-mile project linking Port Canaveral to the Space Center. Proposed by Florida Department of Transportation.

Louisiana. A 40-mile project linking New Orleans Union Passenger Terminal to the airport and the city's northern suburbs. Proposed by Greater New Orleans Expressway Commission.

Georgia. A 40-mile link from Atlanta to Cartersville, Ga., eventually extending to Chattanooga, Tenn. Proposed by Atlanta Regional Commission.

California. A 70- to 75-mile system connecting Los Angeles International Airport to Union Station in downtown Los Angeles to Ontario Airport and east into Riverside County. Proposed by state of California.

Conclusion

The Magnetic Levitation Propulsion System is a promising technology that has the potential of rapid expansion in the 21st century as one of the leading modes of transportation. However there are many hurdles to cross before this becomes a reality. A lot will depend on how successfully the scientists and engineers engaged in Maglev R&D tackle the problems of cutting costs and ensuring reliability and safety away from the test-tracks and into real life projects.

Appendices

Basic Essentials of a Maglev System

Source: "National Maglev Initiative"

The two principal means of levitation are illustrated above Source: "National Maglev Initiative"

Photo courtesy Railway Technical Research Institute

Japan's MLX01 experimental Maglev train

Photo courtesy Railway Technical Research Institute

Above is an image of the guideway for the Yamanashi maglev test line in Japan. Below is an illustration that shows how the guideway works.

Photo courtesy Railway Technical Research Institute