Building a greener future towards carbon neutral dredging operations

Like many companies and organisations, leading UK port body Harwich Haven Authority (HHA) is working towards a net zero environmental impact.

In HHA’s case, it aimed to achieve net zero carbon emissions by 2035 but was struggling to find an environmentally friendly and cost-effective method of dredging to do so.

With international shipping accounting for around 3% of the world’s greenhouse gas emissions and dredged sea sediment estimated to generate up to 6 million tonnes of carbon emissions, these are strong reasons for port authorities to work towards carbon neutral dredging operations to help mitigate climate change.

In the dredging sector, global energy-related CO2 emissions rose 0.9% to a record of more than 36.8 gigatonnes of equivalent carbon dioxide, according to the International Association of Dredging Companies’ report, Dredging in Figures in 2022.

The solution for HHA was to commission its own innovative solution: Tiamat. The new hydrodynamic dredging solution provides a cleaner and greener method of maintenance dredging, that is easy to deploy, adaptable and available at a lower cost.

Unlike traditional methods of dredging, including Trailing Suction Hopper Dredging (TSHD), Tiamat dredges with nature to disperse sediment naturally and there is no need for disposal at a separate site. It is mounted onto a small workboat or multi-cat of 25-27 metres with an ‘A’-frame and is lowered into the water to the required depth. As Tiamat uses a small vessel, European-based boat owners would likely avoid being caught up in the European Union’s Emissions Trading System (ETS).

In 2026, the European Commission will review if general cargo and offshore ships from 400-5,000 gross tonnes will be added to the cap-and-trade system. This would probably include many Water Injection Dredgers and TSHDs, but not the boats pulling Tiamat.

Tiamat works by diluting the sediment on the seabed and pumping it into the upper levels of the water column, so it can be taken away by the current in a non-invasive way. This natural suspension of sediment helps to maintain a healthy estuarian system. And, because it places the sediment back into the water column at the appropriate depth, water turbidity or quality is not impacted.

Further supporting the mission to become carbon neutral, Tiamat removes the need to have to travel back and forth to disposal sites, often several times a day and traffic noise, pollution and road congestion are reduced. This reduces harmful emissions being released into the environment by up to 90%, depending on the location of the disposal site.

Emissions can be even further reduced, if the vessels transporting Tiamat are powered by eco-friendly HvO (hydrotreated vegetable oil) marine fuel. Fuel savings are another benefit here, along with wider environmental benefits for the local area and beyond.

As Tiamat shortens the dredging process, encouraging the sediment to disperse naturally, it supports the ecology of mud flats and minimises disruption to marine creatures and wildlife. With a more natural system for dredging, this means that the process of dredging can be completed in a manner that is kinder to both the natural environment and marine life.

Tiamat is available through Haven Dredging to port authorities and dredging companies around the world, helping to build a greener future towards carbon-neutral dredging operations. For more information or to discuss your need, please contact us for more information.