Société de transport de Montréal 28-701 to 28-708
Société de transport de Montréal 28-701 to 28-708 are Nova Bus LFS HEV buses built in 2008 with the first one delivered on February 13, 2008. They were purchased as part of a program in partnership with the STO to test the feasibility of hybrid buses and the reduction in greenhouse gasses.
The hybrid buses and the six control buses were fitted with data collecting equipment from ISAAC instruments which measured items such as average speed, acceleration, fuel consumption, and distance traveled. Tests were carried out in controlled environments at the Environment Canada laboratories. The tests consisted of ten tests of the control STM and STO buses against the hybrid STM and STO buses in varying operating conditions. In August 2008, outdoor track tests were carried out at PMG Proving Ground in Blainville. This test allowed for the investigation of fuel consumption related to the number of stops and/or load, ability to obtain comparable results for both buses, and identify other aspects that may be observed. The eight STM buses were then put against six standard diesel (control) buses on the same route for one year. Surveys were also taken from drivers of the buses and passengers. This was done in winter 2009.
The trial found an average of 30% fuel savings with the hybrid bus in low average running speed and when distance between stops is short. The tests at Environment Canada concluded that temperature had an effect on fuel consumption. At a temperature of over 20°C, the hybrid bus consumed 37% less fuel than the control bus at 62 litres per 100 kilometres and 92 litres per 100 kilometres respectively. At a temperature of less than 20°C, the hybrid bus's fuel consumption became 75 litres per 100 kilometres where the control bus experienced less aeration. This is can be explained by potential decrease in battery performance, by the rate of the use of the hydraulic fan, or by engine performance. Tests at the PMG Proving Ground showed that the rate of acceleration had a greater impact on the control buses than the hybrid buses. Testing in service showed that hybrid buses did better than the control buses when the number of stops per kilometre increased because with the hybrid system, energy captured during deceleration is used during acceleration resulting in lower demand of the engine. It was also seen that as average speed increases fuel consumption of the hybrid bus and control bus become very similar and fuel consumption goes up as the temperature drops as seen at the Environment Canada test. The auxiliary heating is used more on the hybrid bus as less heat is created by the engine at lower speeds. It was found that gentle acceleration produced better fuel economy in both bus types, but there is much less of an impact on hybrid buses because of the extra energy captured from deceleration and the optimized programming with the hybrid system.
As shown in the Environment Canada test, hybrid buses were found to emit 36% less carbon dioxide emissions, but emitted 5% more nitrogen oxide emissions. For a bus traveling around 70,000 kilometres per year, this translated to a reduction of around 36 tonnes of greenhouse gas emissions. While the cost of a hybrid bus compared to a control bus was high, it was concluded that engine wear should be lower as the engine does not work as hard.
One bus, 28-702, received some modifications to further reduce greenhouse gasses and improve fuel economy. The hydraulic cooling system on this bus was replaced with an electric array of small fans developed by EMP. A hydraulic cooling system has a relatively low energy efficiency and consists of one fan cooling different areas with different needs. The electric system reduces heat loss in the electric transfer from the engine and with a number of fans, different areas can received the optimized cooling they need. A section of additional cooling for the hybrid transmission was added to the roof as there was limited space in the engine compartment and a lack of time to better integrate the system. 28-702 is easily identifiable because of the large aluminum rectangular box on the roof at the rear. The electric cooling system was found to reduce fuel consumption by around 16%.
|Engine||Hybrid system||Seating||Destination sign|
|Cummins ISL||Allison EP40 System||31: American Seating 6468||Axion Orange LED|
|Fleet number||Thumbnail||Date||VIN||License plate||Division||Previous division||Status||Notes|
|28-701||2008||2NVYL82W383000039||A 59264||LaSalle||Active||Received new livery in late 2010.|
|28-702||2008||2NVYL82WX83000040||A 59265||LaSalle||Active||Fitted with rooftop cooling system in February 2009.|
|28-704||2008||2NVYL82W383000042||A 59267||LaSalle||Active||Received new livery in late 2010.|
- Bus History Association 2013 Convention
- Technical Report – Hybrid Technology, stm.info, retreived on 2010-11-28