GHG and shipping: gas vs oil. File Image / Pixabay
Does natural gas as an alternative bunker fuel represent a net greenhouse gas (GHG) gain or loss over conventional fuel? is the question addressed in a new report.
The study, from London's Imperial College and the London-based Sustainable Gas Institute, sees potential for a 10% GHG reduction through gas bunker fuel use, although questions continue to linger over any benefit when taking into account full lifecycle emissions.
"GHG emissions from trucks or ships vary due to differences in engine efficiency, methane slip through the exhaust, engine and fuel system methane emissions and supply chain emissions," the report said.
air pollution emissions can be reduced significantly in shipping by switching to natural gas
"For ships, the equivalent potential for lifecycle emissions reduction is around 10% relative to heavy fuel oil ships.
"However, natural gas fuelled trucks and ships at worst may have lifecycle emissions exceeding current incumbent diesel trucks and heavy fuel oil ships.
"Dual fuel trucks in urban driving cycles or ships using low pressure dual fuel or lean burn engines are most likely to exhibit these high emissions," according to the report.
In addition, the report found that "air pollution emissions can be reduced significantly in shipping by switching to natural gas".
LNG is seen as a viable bunker fuel alternative to oil-derived fuel oil. While GHG concerns remain, in practical terms, a lack of infrastructure to deliver the fuel is seen as constraining its development.
Northern Europe, which has an emerging market in LNG as marine fuel, is expected to provide the best growth for the fuel over the short to medium term.
The report is just the latest attempting to quantify the impact on emissions of switching from oil to gas. A report last year by T&E calculated the GHG savings of switching to gas to be 6% at best.
To download the latest report, click here.