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Electric bus

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New (2004) Massachusetts Bay Transportation Authority Neoplan trolleybus
See also: Tram

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 roof-mounted trolley poles.
    • The gapbus is a bus without rails or surface power lines, and it can share the road lane with other vehicles as well. Power is supplied over a gap of 12cm from a power line embedded in the ground. [1]
  • The onboard stored-electricity bus (autonomous electric buses):

For information on buses using a combination of internal combustion engines and electric propulsion, see Hybrid electric buses and Dual-mode buses.

Capabus

See also: Ultracapacitor

The best ultracapacitors can only store about 5 percent of the energy that lithium-ion batteries hold, limiting them to a couple of miles per charge. This makes them ineffective as an energy storage medium for passenger vehicles. But what ultracapacitors lack in range they make up in their ability to rapidly charge and discharge. So in vehicles that have to stop frequently and predictably as part of normal operation, energy storage based exclusively on ultracapacitors begins to make sense.[2]

China is experimenting with a new form of electric bus, known as Capabus, which runs without continuous overhead lines by using power stored in large onboard electric double-layer capacitors, which are quickly recharged whenever the vehicle stops at any bus stop (under so-called electric umbrellas), and fully charged in the terminus.

A few prototypes were being tested in Shanghai in early 2005. In 2006, two commercial bus routes began to use electric double-layer capacitor buses; one of them is route 11 in Shanghai.[3] In 2009, Sinautec Automobile Technologies[4], based in Arlington, VA, and its Chinese partner, Shanghai Aowei Technology Development Company[5] are testing with 17 forty-one seat Ultracap Buses serving the Greater Shanghai area since 2006 without any major technical problems.[6] Buses in the Shanghai pilot are made by Germantown, TN-based Foton America Bus Co.[7] Another 60 buses will be delivered early next year with ultracapacitors that supply 10 watt-hours per kilogram.

Foton America Bus Co is in talks with New York City, Chicago, and some towns in Florida about trialing the buses.

The buses have very predictable routes and need to stop regularly, every 3 miles (4.8 km), allowing opportunities for quick recharging. The trick is to turn some bus stops along the route into charging stations. At these stations, a collector on the top of the bus rises a few feet and touches an overhead charging line. Within a couple of minutes, the ultracapacitor banks stored under the bus seats are fully charged. The buses can also capture energy from braking, and the company says that recharging stations can be equipped with solar panels. A third generation of the product, which will give 20 miles (32 km) of range per charge or better. [2]

Sinautec estimates that one of its buses has one-tenth the energy cost of a diesel bus and can achieve lifetime fuel savings of $200,000. Also, the buses use 40 percent less electricity compared to an electric trolley bus, mainly because they are lighter and have the regenerative braking benefits. The ultracapacitors are made of activated carbon, and have an energy density of six watt-hours per kilogram (for comparison, a high-performance lithium-ion battery can achieve 200 watt-hours per kilogram), but the ultracapacitor bus is also cheaper than lithium-ion battery buses, about 40 percent less expensive, with a far superior reliability rating.[2][6]

There is also a plug-in hybrid version, which also uses ultracaps.

Future developments

Sinautec is in discussions with MIT's Schindall about developing ultracapacitors of higher energy density using vertically aligned carbon nanotube structures that give the devices more surface area for holding a charge. So far, they are able to get twice the energy density of an existing ultracapacitor, but they are trying to get about five times. This would create an ultracapacitor with one-quarter of the energy density of a lithium-ion battery.[8]

Future developments includes the use of inductive charging under the street, to avoid overhead wiring. A pad under each bus stop and at each stop light along the way would be used.

Solar-powered

Tindo is an experimental battery electric bus being tested in Adelaide, Australia. The word "Tindo" comes from the aboriginal word for sun. The bus will get its electricity from a photovoltaic system on Adelaide's central bus station. Rides are free as part of Adelaide's public transport system.[9]

Zinc

There is a 40-foot (12 m) pure electric bus being developed, using a pre-commercial battery technology. Electric Fuel Corporation is developing and demonstrating a 40-foot (12 m) electric bus powered by a zinc air cell,[10] along with an ultracapacitor. The zinc-air energy device, often described as a battery, converts zinc to zinc oxide in a process that provides energy to the bus. The bus is not recharged; instead, the zinc oxide cartridges are swapped out for new zinc ones. This bus has shown a range of over 100 miles (160 km) in testing and has been demonstrated in Las Vegas, Nevada. However, this technology is in the development phase, and several major hurdles must be overcome before it can be adopted for transit fleet use, including available refueling infrastructure or use in bus stations.[11]

Air conditioning

Solar panels and supercapacitors are used in some electric buses to power the specific air conditioning circuit.

Makers and models

See also: Coachbuilder
Bus with trailer (trailer can be used to store batteries and/or generator - this last to hybridize-)

There are currently more than 25 manufacturers of trolleybuses. See Trolleybus makers.

Makers of other types of all-electric buses (mostly battery buses):

Transit use

For information on where trolleybuses are in use, see Trolleybus and list of trolleybus systems.

Transit authorities that use battery buses or other types of all-electric buses, other than trolleybuses:

Canada

China

Europe

There is an European Union directive that mandates the purchase of electric buses for public services.

Spain

United States

Federal Transit Administration Clean Air Program [33]

California

There is a Californian mandate that 15% of new buses after 2011 be electric.

See also

References

  1. ^ http://www.gizmag.com/kaist-olev-electric-vehicle/12557/
  2. ^ a b c http://www.technologyreview.com/energy/23754/?a=f
  3. ^ [1] (in Chinese, archived page)
  4. ^ http://www.sinautecus.com
  5. ^ http://www.aowei.com/english/index.htm
  6. ^ a b http://www.treehugger.com/files/2009/10/ultracapacitor-electric-buses-china.php
  7. ^ http://www.foton-america.com/
  8. ^ http://www.technologyreview.com/energy/23754/page2/
  9. ^ http://www.ecogeek.org/content/view/1245/
  10. ^ http://www.electric-fuel.com
  11. ^ http://www.fta.dot.gov/documents/Electric_Drive_Bus_Analysis.pdf
  12. ^ http://www.enovasystems.com
  13. ^ http://www.allbusiness.com/manufacturing/transportation-equipment-mfg-automotive/7132521-1.html
  14. ^ http://www.astonbus.com
  15. ^ http://www.bredamenarinibus.it
  16. ^ http://www.ebus.com
  17. ^ http://www.lujoev.com/
  18. ^ http://www.proterraonline.com/
  19. ^ http://www.tecnobus.it/home/it/prodotti.html
  20. ^ http://www.thomasbus.com/
  21. ^ http://www.carolinathomas.com
  22. ^ Thunder Sky website
  23. ^ http://www.tpub.com/content/altfuels10/hvyeng96/hvyeng960011.htm
  24. ^ http://www.thefreelibrary.com/U.S.+Electricar+and+Kaiser+Aluminum+Announce+Memorandum+of...-a015971078
  25. ^ http://www.kaiseraluminum.com
  26. ^ http://www.zondabus.com
  27. ^ http://www.zondabus.com/En/NewsView.Asp?ID=265
  28. ^ http://green.autoblog.com/2010/05/24/montreals-bus-fleet-of-1-300-plus-going-all-electric-by-2025/
  29. ^ http://www.zondabus.com/En/NewsView.Asp?ID=264
  30. ^ http://www.emtmalaga.es/inter/emt/interior_detalle.jsp?id=2460&tipo=20
  31. ^ http://www.noticiasdeautobus.es/2008/06/18/el-ayuntamiento-refuerza-la-escuadra-de-la-emt-con-210-nuevos-autobuses/ Template:Es icon
  32. ^ http://www.energie-cites.eu/db/figueres1_577_en.pdf
  33. ^ http://transit-safety.fta.dot.gov/publications/cleanair/DesignGuidelines/HTML/DesignGuidelines.htm
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