CEDA Iberian Conference

Dredging for sustainable port development


27-28 October 2016, Lisbon, Portugal

E.C. van der Blom, Royal IHC, The Netherlands

Sustainability is a major topic in the global dredging industry and it has become an important driver in Royal IHC's research & development programs. As a developer, designer and builder of dredging vessels and equipment, Royal IHC is well aware of the environmental footprint of these vessels. Especially for complex dredging vessels, like trailing suction hopper dredgers, research & development now focusses on reduction of the environmental footprint, next to improving production performance and cost effectiveness.

Reduction of exhaust gas emissions in one of the main challenges. Since 2015 strict SOx emission regulation is in place for Emission Controlled Areas (ECA's), limiting the level of SOx emission to 0.1%. Strict limits for NOx emissions and CO2 emission are expected in the future. Emission regulation will have impact on vessel design and vessel operations. Both vessel owners and vessel designers are confronted with tough questions and considerations. Costly measures are needed, whether it is the installation of exhaust gas after treatment, the application of new types of engines or switching to other types of fuel.

An option that looks very promising is Liquefied Natural Gas (LNG). LNG reduces exhaust gas emissions drastically. SOx emissions and Particulate Matter (PM) are almost eliminated with LNG. NOx emissions are reduced by approx. 80% and CO2 emissions by approx. 20%. Compared to other emission reduction measures, LNG is a very environmentally friendly solution that can meet the strictest emission levels. Unlike other options, LNG provides ship owners with earn back potential on their investment, making it an economical viable option. This has led to the development of the worlds' first LNG powered Trailing Suction Hopper Dredgers. Right now, Royal IHC is building 3 LNG powered Trailing Suction Hopper Dredgers for its customer DEME. These vessels range from the midsized 8.000 m3 hopper dredger 'Scheldt River' and small sized 3.500 m3 hopper dredger 'Minerva' to the large 15.000 m3 hopper dredger 'Bonny River'. The design challenges that come with the integration of LNG in a trailing suction hopper dredger will be presented.

Also other sustainable innovations developed by Royal IHC will be presented. Research on fuel saving started with extensive measurements of operational profiles of dredging vessels. This led to thorough understanding of the power consumption of drive trains in different phases of the dredging cycle. Based on this insight, drive train designs can now be configured and optimized for minimal fuel consumption. It also led to the development of 2-speed propulsion, saving fuel when sailing in partial load conditions. Fuel saving potential is also pursued by minimizing hull shape resistance of dredging vessels and by optimizing dredging processes using intelligent dredging automation.

Another development to be presented is the airless overflow. Trailing suction hopper dredgers often generate turbidity as a result from overflow activities. Royal IHC has developed an airless overflow system, that reduces the amount of air entrapped in the overflow stream and thereby reducing the size of the overflow plume.

Last update: 2 October 2016