HybridExperience

Hybrid transit buses are starting to be adopted by an increasing number of transit fleets. In Canada, fleets such as BC Transit in Victoria and TransLink in Vancouver have been testing hybrid buses (pdf) and will soon be adding more in their fleets.

Hybrid bus technology is similar to that used in hybrid cars and trucks.  An important difference is that transit operators are able to spec many features in the buses they require for their fleets, such as either parallel or series hybrid power trains and the brand and size of diesel engine.

The operating parameters of each transit fleet are unique making it important that a transit operation optimize the hybrid system for their application.  Parameters such as load factors, city vs. highway routes, terrain and diesel engine size directly affect the performance benefit of hybrid buses.  Like current hybrids the fuel improvements of a hybrid bus over a conventional diesel bus is greatest in high load factor, frequent idle and start/stop applications. 

The premium price of current hybrid bus technology can be quite substantial, upwards of $200,000 per bus.  As a result transit operators are conducting detailed life-cycle cost and emission benefits of hybrids to ensure full benefits are achieved. Transit agency experience (pdf) appears to vary widely with fuel savings ranging from 10 to 50 percent, depending on a host of variables. As is the case with light duty hybrids the hybrid technology for buses is also evolving based on learning from early demonstrations. 

In May 2008, an Edmonton Transit report recommended replacing the existing trolley system with hybrid transit buses, over using trolley or clean diesel options. Hybrids were found to use 15-20% less diesel than a diesel bus, providing the best opportunity to reduce overall emissions, at a lower lifecycle cost than trolleys. (Direct link to pdf report.)

The US National Renewable Energy Laboratory (NREL) has tested and reported on many different hybrid transit bus demonstration programs.

Hybrid technology is still developing but as in other types of applications there appears to be significant fuel savings and both smog and greenhouse gas emission reductions from hybrid transit buses. 

As Canadian data becomes available it will be posted on this site.

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