Dredging’s role in the maritime energy transition
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Photo Credit: Van Oord
While shipping is transitioning to Net Zero, dredging as a sub-sector needs to assess its vessels and vessel construction to determine whether these align with the wider maritime notion of an energy transition.
The global greenhouse gas (GHG) strategy set by the IMO aims to halve annual GHG emissions from shipping by 2050 compared with 2008 emission levels and a 70% carbon reduction by 2050 compared with 2008 levels. However, dredging companies in Europe must aim to be carbon neutral by 2050 to abide by EU climate regulation.
These targets have encouraged the development of low-emission technologies which have resulted in the exploration of alternative fuels, automated vessels, and discussions regarding the dredging industry's involvement in the maritime energy transition.
As a result, vessel construction must comply with current global policies while also potentially anticipating future legislation, which is why the new generation of dredgers is increasingly constructed with flexibility in mind.
Many companies have opted to use technology to filter and treat their emissions. A good example of this is Jan De Nul’s Ultra Low Emission Vessles (ULEVs), which are equipped with a filter system that processes exhaust gases and prevents nanoparticle emissions. This is seen as a particularly flexible system because it is designed to filter out the vast majority of nanoparticles (reported at 99% of nanoparticles) from vessels irrespective of the fuel used.
Other operators have worked to comply with regulations in other ways, with choice of fuel often seen as a means to reduce emissions.
LNG dual-fuel flexibility
Finding low carbon alternatives to fossil fuels is highly important to reduce GHG however, given uncertainty about a global, cost-effective supply of alternative fuels has led many operators to select flexible dual-fuel engines. A growing number of trailing suction hopper dredgers (TSHDs) are equipped with these engines that will run on liquified natural gas (LNG) when supplies are available and on diesel if there are LNG shortages.
The primary reasons for LNG’s popularity are its low-carbon footprint, cost-efficiency, reduced emissions of sulphur oxide and nitrogen oxide (as compared to traditional fuels) and its ability to mix with biogas to reduce emissions further. Viewed as a short-term transition fuel, LNG provides a tried and tested method for reducing carbon emissions while waiting for technological advances or greater availability of sustainable alternative fuels.
DEME is perhaps best known for its choice of LNG-compatible dual fuel engine for the vessel Spartacus, which CEDA Industry News has written about here. But other companies are also going down this route. Van Oord recently unveiled the Vox Ariane, the first TSHD in its fleet equipped with a dual fuel system capable of operating on LNG. Van Oord has ordered a total of three dual-fuel TSHDs from Keppel Offshore & Marine's Singapore-based shipyard that are intended to replace existing vessels within the company's fleet. The vessels feature an energy-efficient design that reduces fuel consumption and carbon emissions, which has allowed the Vox Ariane to qualify for a Green Passport and a Clean Ship notation from Bureau Veritas.
The second LNG TSHD, Vox Apolonia, was delivered on 13 December 2022 and was being prepared to set sail in the Netherlands at time of press. The third sister vessel, Vox Alexia is currently under construction in Singapore and is slated to be operational by 2023.
Istanbul-based Mavi Deniz, which operates a fleet of oil pollution control vessels in addition to building and operating dredgers, has built a series of seven new TSHDs (TSHD 500-3500) that are equipped with a dual-fuel engine that can burn a number of fuels including LNG, liquid biofuel, light fuel oil (LFO), and heavy fuel oil (HFO).
The vessels can switch between fuels without loss of power and speed demonstrating the advancement that dredger builders have made to meet the demands of the energy transition. Integrating operational flexibility into the vessel design is becoming increasingly common in order to future-proof modern fleets.
Electric capabilities
Battery power is another strong contender for greening dredging vessel operations, particularly since there is the possibility of using completely renewable electricity. While this has traditionally been a challenge given the power-intense requirements of marine engineering and dredging, advances in battery technology - combined with regulatory incentives to reduce emissions - have made this more of a reality.
As a result, the sector is beginning to welcome a new generation of fully electric powered cutter suction dredgers (CSDs). Damen unveiled their range of electric CSDs in 2020, with the E-CSD 650 (watch a video of the vessel here), and set the stage for an increase in electric dredger building. Royal IHC recently followed suit and expanded its existing portfolio of the IHC Beaver CSD series with electrical counterparts. The new range of electric dredgers has an identical dredging and hydraulic installation to its non-electric counterparts, with the advantage of being able to exchange the diesel-powered main pontoon for an electrical one.
In October of this year, the Netherlands-based company commissioned the first in a series of four electrically-powered CSDs for Brazilian mining company Vale. The electric dredgers will be operating in Project Gelado where they will reprocess iron ore tailings.
This is just the beginning of the creation of innovative technologies which comply with the latest environmental regulations. More are in development with fuel cell technology being a likely contender for the advancement of electric-powered vessels, evident with the Occitanie Region ordering a hybrid hydrogen dredger in Spring 2022. The vessel will be equipped with a marine-certified fuel cell and will be used for the maintenance of its ports.
Biofuel on the rise
While many of the alternative fuels are being put into action on newbuilds, there are a number of means by which the existing fleet can improve its green credentials. The most commonly used means to reduce carbon emissions is the use of biofuels, which can be used by existing vessels designed to run on HFO.
Boskalis led the charge in the dredging sector through its biofuel pilot program to accelerate the scalable development of sustainable, reliable and affordable drop-in biofuels. This summer its Willem Van Oranje Hopper Dredger was powered by 100% biofuel while improving Rhos On Seas coastal defences off the coast of North Wales.
Van Oord has also explored use of biofuels, trialling it on its trailing suction hopper dredger HAM 316 in 2010. Late last year, Boskalis and Van Oord used bio-fuel for their dredgers when deepening the inner harbour area of Harwich Haven late last year (read the CEDA Industry News Article here).
Jan De Nul also used biofuel for its two suction hopper dredgers, 'Kaishuu' and 'Alexander von Humboldt' when performing maintenance dredging works in the Port of Hamburg between June and December 2021.
Future fuels
Currently under investigation is the use of methanol as a low-carbon fuel with the research aiming to develop clean energy technology that can be used by offshore work ships and high-powered dredgers. The Methanol as an Energy Step Towards Zero-Emission Dutch Shipping (MENENS) program is sponsored by the Dutch Government’s Netherlands Enterprise Agency, with Boskalis, Damen Workboats, and Van Oord, being some of the partners of the consortium.
Other notable research into methanol as a maritime fuel has been conducted by the Green Maritime Methanol Consortium of which Boskalis, Damen, DEME, Royal IHC and Van Oord, among others, are members. This consortium has previously investigated the feasibility of methanol as a sustainable fuel for the maritime sector.
Ship operators are also exploring ammonia and hydrogen as fuels although there are serious concerns about the toxicity of the former and the viability of the latter. In many instances, carbon capture is seen as an extremely attractive alternative - particularly if it can be sold on for industrial use (eg: as a fertiliser).
As we progress towards 2050, there can be no doubt that there will be significant developments in both modern fuels and technologies. What remains to be seen is the pace of this progress and whether these new green solutions are right for dredging.
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