Developing sustainable dredging solutions

Transition to zero emission carbon-neutral vessels is a challenge for the maritime sector – this is especially the case for dredging vessels, which need to be capable of operating under heavy conditions and have projects around the world.

For these vessels, autonomy and fuel logistics are particularly challenging, especially when alternative fuels with a lower carbon footprint are considered.

The effect of emission cost scenarios and fuel price scenarios on the economic feasibility of the project are very important factors, in parallel with the environmental performance.

The result is that demand for clean dredging solutions has never been higher.

Pushing the boundaries for fuel solutions, energy efficiency, automation and engineering solutions are nowadays, more than ever, in the focus of the dredging companies.

A couple of days ago, Rohde Nielsen A/S introduced new dredgers Ask R and Embla R into the dredging market.

According to the Copenhagen based company, these are probably the most innovative and environmentally friendly split trailing suction hopper dredgers (TSHDs) ever built.

The 2700 m3 hybrid dredgers are diesel electric and equipped with powerful battery packages of 600 kW and an advanced Siemens BlueDrive PlusC energy dispersion system which enables superior energy efficiency.

The exhaust is cleansed through tailored diesel particulate filters (DPF) and selective catalytic reduction (SCR), allowing Ask R and Embla R to meet and exceed even the strictest emission standards (e.g. European Emission Standard Stage V).

“Higher demands for sustainable solutions and the generally growing commitment to sustainability across society has clarified the principal importance of us continuing our already exceedingly sustainable business practices,” said Rohde Nielsen.

Summer 2020 saw Damen’s commitment to the shift to electricity extend to dredging with the unveiling its first Electric Cutter Suction Dredger, the ECSD 650.

According to the Dutch shipbuilder, these vessels are ideal for operations in urban and environmentally-sensitive settings – the electrical power also provides a significant reduction in noise compared to diesel engines .

The new class is an adaptation of the conventional CSD 650.

According to Damen, in the ECSD 650, the standard diesel engines have been exchanged for electrical engines and the void in the aft starboard side pontoon has been repurposed to host the electrical control centre.

The dredger’s electrical system is easily maintained without the need for special crew training and the associated reduction in vibrations during dredging ensures a more comfortable experience for the crew, Damen said.

As modular vessels, both can be broken down into containerised components for transportation and subsequent reassembly on-site.

Another Dutch shipbuilding giant, Royal IHC, received an ‘approval in principle’ (AiP) recently from classification society Bureau Veritas for the design of a hydrogen-fuelled trailing suction hopper dredger (TSHD).

According to IHC, the AiP means that the proposed design of the vessel, encompassing its features and specifications, has been deemed acceptable in this early stage and that the hydrogen system has been safely integrated.

The exploration phase started in 2019 with the aim of developing a vessel that can be operational in 2024. 

The new dredgers will contribute to the reduction of greenhouse gas emissions as well as harmful exhaust gas emissions in close proximity to the coast and coastal cities.

When operating on hydrogen the vessel emits only water vapour. 

“The reception of the AiP gives Royal IHC and Rijkswaterstaat the confidence to continue on the path towards zero emissions and further develop the LEAF hopper as a solution for CO2 neutral coastal protection works,” the company said.

A range of solutions for sustainable dredging exists and an assessment of these options often proves to be challenging for decision makers.

The degree of the impacts of dredging depends on:

• extent of the areas dredged,

• frequency and duration of dredging activities,

• characteristics and the sensitivity of the areas dredged and their surroundings,

• dredging techniques applied as well as relationships with other uses and users of the system.

A higher level of sustainability in the dredging industry can be reached technically by optimizing the vessels as well as by proper operation and project management.

In order to contribute to a global level-playing balance between sustainability and technology that truly benefits nature and humans, different shipbuilders actively participate in the development of legislation and standards for the industry.