The recent announcement of changes to public bus services is a good opportunity to re-examine whether bus fleets, which currently run on diesel engines, can be gradually replaced with diesel-hybrid or petrol-hybrid engines.
Compared to petrol engines, diesel engines produce higher amounts of PM2.5, the small airborne particles that were recently included in the Pollutant Standards Index. These particles penetrate deeper into the lungs and evade the body's natural defences against airborne pollution.
The stop-start and low-speed travelling mode of buses puts them in good stead to "go hybrid".
While it appears that both bus operators have previously tried hybrid systems, these trials seem to have stopped. It may be that the lithium-battery technology or hybrid powertrain transmission systems have been found wanting, either for cost or safety reasons.
Recent technology developments and the increased commercialisation of hybrid systems may eventually make these systems serious contenders for use in future bus fleets.
The current success of Tesla Motors in selling entirely electric vehicles is also an important development.
There should be greater impetus to move away from diesel engines to reduce their detrimental effects on our air quality.
Lim Wei Jan
This article was first published on June 05, 2014.
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