Bruce, can you please explain the technology behind the LNG truck engines manufactured by Westport in simple terms?
Bruce: The Westport HD engine offered in Australia uses high-pressure direct injection (HPDITM) technology. With direct injection, the combustion process is identical to the diesel-cycle combustion, with fuel injected directly into the combustion chamber at the end of the compression stroke.
The Westport HPDI technology injects a small quantity (about 5 per cent on average) of diesel fuel at the beginning of the power stroke to provide sufficient energy to auto-ignite the natural gas injection that immediately follows the diesel injection. This method eliminates the possibility of pre-ignition or detonation that can occur with pre-mixing of air and fuel on the intake stroke.
The Westport HD system includes an LNG pump installed in the LNG fuel tank to efficiently pressurise the natural gas fuel to enable the high-pressure injection of natural gas.
From the general public’s perspective, what are the driving forces behind LPG/CNG conversions?
Natalie: Definitely cost. As part of ABMARC’s LPG report, we conducted an LPG user survey and the number one reason respondents chose to buy or convert to an LPG vehicle was to lower their running costs. The survey identified the socio-economic benefits of LPG in providing mobility to families, pensioners and low income earners. The results showed that LPG owners typically drove SUVs or large passenger vehicles, lived in the outer suburbs, and had lower incomes than the reference group. It was clear that LPG was used to help balance household budgets or enable family activities such as caravanning or horse riding.