Exhaust gas treatment better than LNG as fuel

Sarah Carter
Sarah Carter

17 March 2017


The same or even better results down to a level in accordance with the future EU Stage V requirement can be achieved by using exhaust gas treatment, and the important environmental and operational downsides of LNG are avoided, says a report in Jan De Nul Group. LNG (Liquefied Natural Gas, consisting mostly of methane) is being promoted as an environmental-friendly fuel. It has a number of advantages: for the same power less greenhouse gas CO2 is emitted, and emissions of some contaminants such as NOx, SOx, Particulate Matter are lower compared to a diesel engine on fuel oil, without exhaust gas treatment system. However, the same or even better results are achieved by using exhaust gas treatment, and the important environmental and operational downsides of LNG are avoided. Methane leakages (during production, transport, and bunkering) and methane slip in the dual fuel engines (gas that is not burned and directly released in the atmosphere) are significant. Methane is a very potent greenhouse gas: over a 100 year period, the effect of methane on global warming is 34 times higher than the same amount of CO2. As a result, most studies conclude that with current technology, LNG as a fuel is not better, and in most cases worse than fuel oil with respect to global warming. The availability of LNG is poor. In addition, due to space and cost restrictions, LNG dredgers have very limited capacity for LNG, and therefore autonomy of only about 1 week. In practice, a LNG dredger is only occasionally, and/or in a limited geographical area, capable of operating with LNG. Normal fuel oil will have be used for most of the time or in most of the world, and therefore without any improvement with respect to emissions. Photo: Clean Marine