Gyrobus
Encyclopedia
Electric bus
An electric bus is a bus powered by electricity.There are two main electric bus categories:* Non-autonomous electric buses:**The trolleybus is a type of electric bus powered by two overhead electric wires, with electricity being drawn from one wire and returned via the other wire, using two...
that uses flywheel energy storage
Flywheel energy storage
Flywheel energy storage works by accelerating a rotor to a very high speed and maintaining the energy in the system as rotational energy...
, not overhead wires
Overhead lines
Overhead lines or overhead wires are used to transmit electrical energy to trams, trolleybuses or trains at a distance from the energy supply point...
like a trolleybus
Trolleybus
A trolleybus is an electric bus that draws its electricity from overhead wires using spring-loaded trolley poles. Two wires and poles are required to complete the electrical circuit...
. The name comes from the Greek language
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
term for flywheel
Flywheel
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed...
, gyros.
While there are no gyrobuses currently in use commercially, development in this area continues.
Development
The concept of a flywheel-powered busBus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
was developed and brought to fruition during the 1940s by Oerlikon (of Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
), with the intention of creating an alternative to battery-electric buses for quieter, lower-frequency routes, where full overhead-wire electrification could not be justified.
Rather than carrying an internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
or batteries
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
, or connecting to overhead powerlines, a gyrobus carries a large flywheel that is spun at up to 3,000 RPM by a "squirrel cage" motor. Power for charging the flywheel was sourced by means of three booms mounted on the vehicle's roof, which contacted charging points located as required or where appropriate (at passenger stops en route, or at terminals, for instance). To obtain tractive power, capacitors would excite the flywheel's charging motor so that it became a generator, in this way transforming the energy stored in the flywheel back into electricity. Vehicle braking was electric, and some of the energy was recycled back into the flywheel, thereby extending its range.
Fully charged, a gyrobus could typically travel as far as 6km on a level route at speeds of up to 50 to 60 km/h, depending on vehicle batch (load), as top speeds varied from batch to batch. The installation in Yverdon-les-Bains
Yverdon-les-Bains
Yverdon-les-Bains is a municipality in the district of Jura-Nord vaudois of the canton of Vaud in Switzerland. It is the seat of the district...
(Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
) sometimes saw vehicles needing to travel as far as 10 km on one charge, although it is not known how well they performed towards the upper end of that distance.
Charging a flywheel took between 30 seconds and 3 minutes; in an effort to reduce the charge time, the supply voltage was increased from 380 volts to 500 volts. Given the relatively restricted range between charges, it is likely that several charging stops would have been required on longer routes, or in dense urban traffic. It is not clear whether vehicles that require such frequent delays would have been practical and/or suitable for modern day service applications.
The demonstrator was first displayed (and used) publicly in summer 1950 and, to promote the system, this vehicle continued to be used for short periods of public service in a myriad of locations at least until 1954.
In 1979, General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
was awarded a $5 million four year contract by the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
government, the Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
and the Department of Transportation
United States Department of Transportation
The United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966, and began operation on April 1, 1967...
, to develop a prototype flywheel bus.
In the 1980s, Volvo
Volvo
AB Volvo is a Swedish builder of commercial vehicles, including trucks, buses and construction equipment. Volvo also supplies marine and industrial drive systems, aerospace components and financial services...
briefly experimented with using flywheels charged by a small Diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
and recharged via braking energy. This was eventually dumped in favour of using hydraulic accumulators
Hydraulic accumulator
A 'hydraulic accumulator' is an energy storage device. It is a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure by an external source. That external source can be a spring, a raised weight, or a compressed gas...
.
During the 1990s, CCM had developed a flywheel for both mobile and stationary applications.
In 2005, the Center for Transportation and the Environment, working with the University of Texas at Austin
University of Texas at Austin
The University of Texas at Austin is a state research university located in Austin, Texas, USA, and is the flagship institution of the The University of Texas System. Founded in 1883, its campus is located approximately from the Texas State Capitol in Austin...
, Center for Electromechanics, Test Devices, Inc., and DRS Technologies sought funding for the development of a prototype gyrobus.
Early commercial service
The first full commercial service began in October 1953, linking the Swiss communities of Yverdon-les-BainsYverdon-les-Bains
Yverdon-les-Bains is a municipality in the district of Jura-Nord vaudois of the canton of Vaud in Switzerland. It is the seat of the district...
and Grandson
Grandson, Switzerland
Grandson is a municipality in the district of Jura-Nord Vaudois in the canton of Vaud in Switzerland.During the Burgundian Wars, Charles the Bold was defeated near here in the Battle of Grandson on 2 March 1476.-History:...
. However, this was a route with limited traffic potential, and although technically successful it was not commercially viable. Services ended in late October 1960, and neither of the two vehicles (nor the demonstrator) survived.
The next system to open was in Léopoldville in Belgian Congo
Belgian Congo
The Belgian Congo was the formal title of present-day Democratic Republic of the Congo between King Leopold II's formal relinquishment of his personal control over the state to Belgium on 15 November 1908, and Congolese independence on 30 June 1960.-Congo Free State, 1884–1908:Until the latter...
(currently Kinshasa
Kinshasa
Kinshasa is the capital and largest city of the Democratic Republic of the Congo. The city is located on the Congo River....
in the Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...
). Here there were 12 vehicles (although apparently some reports suggest 17), which operated over four routes, with recharging facilities being provided about every 2 km. These were the largest of the gyrobuses, being 10.4 m in length, weighing 10.9 tonnes, carrying up to 90 passengers, and having a maximum speed of 60 km/h (about 37 mph).
There were major problems related to excessive "wear and tear". One significant reason for this was that drivers often took shortcuts across unpaved roads, which after rains became nothing more than quagmires. Other problems included breakage of gyro ball bearings, and high humidity resulting in traction motor overload. The system's demise, however, came because of high energy consumption. The bus operator deemed that 3.4 kWh/km per gyrobus was unaffordable, so closure came in the summer of 1959 with the gyrobuses being abandoned.
The third location to use gyrobuses commercially was Ghent
Ghent
Ghent is a city and a municipality located in the Flemish region of Belgium. It is the capital and biggest city of the East Flanders province. The city started as a settlement at the confluence of the Rivers Scheldt and Lys and in the Middle Ages became one of the largest and richest cities of...
, Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
. Three gyrobuses started operation in late summer 1956 on a route linking Ghent and Merelbeke
Merelbeke
Merelbeke is a municipality located in the Flemish province of East Flanders, in Belgium. The municipality comprises the villages of Bottelare, Lemberge, Melsen, Merelbeke proper, Munte and Schelderode. On January 1, 2006, Merelbeke had a total population of 22,353. The total area is 36.65 km²...
(the route Gent Zuid - Merelbeke). The flywheel was in the center of the bus, spanning almost the whole width of the vehicle, and having a vertical axis of rotation.
The Ghent - Merelbeke route was intended to be the first of a proposed multi-route network. Instead its Gyrobuses stayed in service for only three years, being withdrawn late autumn 1959. The operator considered them unreliable, "spending more time off the road than on", and that their weight damaged road surfaces. They were also considered to be energy hungry, consuming 2.9 kWh/km—compared with between 2.0 kWh/km and 2.4 kWh/km for trams with much greater capacity.
One of Ghent's gyrobuses has been preserved and restored, and is displayed at the VLATAM-museum in Antwerp. It is sometimes shown (and used to carry passengers) at Belgian exhibitions, transport enthusiasts' bazaars, etc. The tram depot in Merelbeke has been closed since 1998, but it still stands, as it is protected by the law.
Advantages
- Quiet
- "Pollution-free" (Pollution confined to generators on electric power grid.)
- Runs without rails (Once thought of as an advantage because the route could be varied at will.)
- Can operate flexibly at varying distances
Disadvantages
- Weight: a bus which can carry 20 persons and has range of 20 km requires a flywheel weighing three tonnes.
- The flywheel, which turns at 3000 revolutions per minute, requires special attachment and security—because the external speed of the disk is 900 km/h.
- Driving a gyrobus has the added complexity that the flywheel acts as a gyroscopeGyroscopeA gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
that will resist changes in orientation, for example when a bus tilts while making a turn, assuming that the flywheel has a horizontal rotation axis.
Further developments
After the Gyrobus was discontinued in all locations, there have been a number of attempts to make the concept work. Recently, there have been two successful projects, though the original idea of storing energy has been changed considerably: In Dresden, Germany there is the "Autotram", a vehicle that looks like a modern tram, but moves on a flat surface, not on tracks. It has run since 2005 and is powered by a flywheel, though the wheel is small and only used to store energy from braking. The main source of energy is a fuel cell. The second successful vehicle was the Capabus, which ran at the Expo 2010 in Shanghai. It was charged with electricity at the stops - just like the Gyrobus was. But the Capabus didn't store the energy in a flywheel. It used capacitors.External links
- Electric buses in citytransport.info - with a photograph showing two gyrobuses at a charging point http://citytransport.info/NotMine/Reed001a.jpg.
- Buses Worldwide - some of the information contained in this article comes from the January / February 2005 issue of "BusesWorldWide" Magazine as issued by the organisation of the same name.
- Technology in Parry People Movers—shows how the same technology is being transferred to ultralight TramTramA tram is a passenger rail vehicle which runs on tracks along public urban streets and also sometimes on separate rights of way. It may also run between cities and/or towns , and/or partially grade separated even in the cities...
s - Flywheel Kinetic Energy Recovery System
