My answer would bore most participants in this forum so I will start a thread on the Science and Medecine forum.
mark70920
You're absolutely right that diesel engines have a very expensive injector system rather than the spark ignition a 100% LPG or LNG reciprocating engine would need but many of them also have superheavy duty bearings and other engineering a heavy duty cycle gas engine might need. Wasting that beautiful injector system seems a bit sad but a long life gas engine needs the robust engineering in the rest of a big diesel.
The most efficient gas engines are probably combined cycle gas turbines but these are ultraexpensive. High temperature ceramic fuel cells might come close to matching their efficiency. These fuel cells could conceivably be used to operate a heavy transport vehicle but vibration could be a problem. Ceramic fuel cells approach their max efficiency when used to heat, cool and power commercial buildings.
There is plenty of technology available to offset the price on fossil carbon and the Oz rate is set at a level that will promote improved efficiency. The effective rate of this levy should be discounted because so much of it is returned to households via direct payments and to industry via tax cuts.
