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Supported by:
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AFD Show Cases |
| Ethanol buses in Stockholm |
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Stockholm (Sweden)
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The Stockholm Public Transport Authority (SL) has decided that all buses (2000) shall use renewable fuels by 2025. Today the fleet consists of 25 biogas buses and 400 ethanol buses. More ethanol buses are on the way in. Ethanol buses have a modified diesel motor and runs on E95, ethanol blended with a ignition improver. |
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Objectives:
BEST (Bioethanol for Sustainable Transport) is a project supported financially by the European Union. Several of the investments and some of the work done got some support from EU. The bigger part, however, has been financed by the project partners. The aim of the project is to put more then 10.000 ethanol cars and 160 ethanol buses in operation and to open an E85 fuel station as well as an E95 fuel station. Furthermore, low blends with petrol and diesel will be developed and tested.
One partner is Stockholm in Sweden. Stockholm Local Transport Authority (www.sl.se) is responsible for all the public transport in the Stockholm County, a city with 1.6 million inhabitants. Buses are an important part of the public transport system in Stockholm. There are about 2000 buses in the fleet. SL started to introduce ethanol buses in the late 1980's and has had very good experiences with them so far. Now a decision of a completely fossil fuel free bus fleet has been taken and the ethanol buses will be the solution to reach that goal.
Implementation
The first ethanol buses started to operate 1985 in Stockholm. In 2006, about 400 buses runs on ethanol. In comparison to a diesel bus, the ethanol bus concept involves three principally differences: the buses have an ethanol engine, the fuel is pure ethanol and has a different infrastructure compared to diesel. The ethanol buses are standard Scania Omni buses with a 9 litres Scania compression-ignition engine, slightly modified to operate on bioethanol bus fuel. The bioethanol bus fuel, E95, is a liquid homogeneous and stable fuel, which is developed for heavy-duty, ethanol compression-ignition engines. It is composed by ethanol and an ignition improver (5 %). The only thing which should be noted is that the bus should always be refuelled from the ethanol pump at the bus depot. For safety reason the fuel tank installation also must be a dedicated tank for ethanol use.
Some ethanol is produced within EU. The greater part is imported from other parts of the world (mainly Brazil).
Results:
There are emission benefits from using ethanol in buses. Tests have showed that the regulated emissions such as nitrogen oxides (NOx), carbon monoxide (CO), hydro carbon (HC) and particulate matters (PM) from ethanol buses are substantially reduced compared to diesel buses (without consideration upstreamed processes). Ethanol has lower energy content, which involves about 60% higher fuel consumption compared to diesel. The energy content for ethanol is about 38% lower than the one for diesel. The costs for an ethanol filling station are exactly the same as for diesel. The only additional cost is for the sprinkler plant, which is needed due to the increased fire hazard of the ethanol fuel. The additional cost of buying an ethanol bus today is about 11.000-22.000 Euro. Stockholm Transport, SL, who operates the largest ethanol bus fleet today estimates the increased operation costs to about 7.000 Euro/y. The ethanol price and fuel taxes are an important factor for the total cost.
Other
Find more information about ethanol buses at Ethanolbus or Stockholm Public Transport Authority (SL)and Scania
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Author
Kristina Birath
Contact
Maria Ljung
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