clean maritime 
For thousands of years, ships and shipping have played a critical role in developments across the globe. They have enabled the exchange of goods and ideas to occur between nations, and for connections to be established long before the technological age. Despite recent technical advances, around 80% of global trade by volume is still carried by sea. While that brings obvious benefits it also means international shipping contributes to 2.2% of global CO2 emissions, equalling that of Germany! This figure is in addition to other maritime activities, such as the development and servicing of offshore wind farms, so when considered in its entirety, the maritime sector’s carbon footprint is significant.
International trade is deeply embedded in how we live and how the world’s economies survive and thrive. Over centuries, we have become reliant on the products brought to us on the ocean. It means that addressing shipping emissions in the 21st Century is not as simple as saying: “If it’s been shipped, don’t buy it”. Yes, ships and boats have to make a move away from fossil fuels, but in doing so there are major challenges to first address.
Any boat needs an energy source to propel it and, as energy sources go, fossil fuels are incredibly energy dense when compared to alternatives. It is estimated that every 1 litre of fuel burned today required 27 tonnes of prehistoric plant matter to form it. This high energy density has meant the overwhelming majority of ships and boats we use today are built and designed with it as a core consideration. The amount of cargo they carry, the speed they travel, and the associated economics will all be impacted by a change in fuel source.
To some, this may make the prospect of moving away from fossil fuels intimidating, but the maritime sector has to a large extent been here before. Transitions from sail to steam, and then from steam to diesel, have both shown that the seemingly impossible is in fact far from that. And with the technologies and innovation now at our disposal – not to mention the growing global appetite for change – the transition to net zero is undoubtedly achievable.
In the past, providing the infrastructure necessary to service a vessel’s energy requirements, and selecting its most suitable energy source has always been a cause for debate. There is little doubt this will continue. In fact, the only certainty is that a wide range of appropriate technologies will be required to tackle maritime decarbonisation. There won’t be a single silver bullet that serves as a catch-all replacement for fossil fuels.
In trying to prepare for this, one of the many challenges is that ships and boats can have a working lifespan of between 20 and 40 years. It means a vessel being designed today needs to have provision to use a zero emission propulsion technology, if we are to meet the UK Government’s target – and that of many other nations – for a zero emission shipping fleet by 2050. 
The UK Government’s Clean Maritime Plan, which stated this ambitious goal, was first published in 2019 and an updated version of it is expected during the course of 2023. To help bring about the seismic changes required to meet these aims, the Government established the Clean Maritime Demonstration Competition. Funded through Innovate UK, the competition is designed to unite industry, academia and public bodies in collaborations to advance new technologies. Successful projects we have undertaken include pioneering electric vessel charging networks, the development of electric outboards, and the building of fully electric maritime vessels. 
By creating technologies at a smaller scale, it enables the innovations already made in land-based transport to migrate to the coast. From there, is the potential to scale up into vessels suitable for offshore operation. Yet there are still challenges with this approach. While batteries are underpinning the transition of road transport to net zero, and will be suitable for short-range smaller vessels, current battery technologies have about 47 times less energy per kilo than diesel. For larger ships, they are not currently a viable solution. Other replacement technologies such as ammonia have also gained traction as the lack of carbon in the ammonia molecule makes it an appealing replacement for large diesel engines. Unfortunately, this is no guarantee of having a lower environmental impact, as there are concerns around both the long-term safety and potential increase in emissions of Nitrogen Oxides.
With all potential solutions to this global problem, one thing that is currently lacking is data – on what works, what doesn’t and what the impact of it will be. Before we get too far down development pathways, we need further research to ensure we don’t sleepwalk from one environmental problem to another. Our holistic approach unites engineers, mathematicians, designers and experts in international trade to answer some of these questions. Through working closely with industry, we can ensure the challenges of maritime decarbonisation can be met, and our ocean environment improved in every sense.

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Fuel powering shipping and wider port activity has been some of the most polluting fuel used across all transport modes. Globally, the maritime sector needs to do more to reduce greenhouse gas emissions and air pollutants as these affect the environment profoundly accelerating climate change.
Our researchers are working at the leading edge of clean maritime innovation, charting a course for net zero. Collaborating with industry and the wider scientific community, we transform research into real-world solutions to challenges faced by the marine and maritime sectors to achieve zero-emission shipping.
Clean Maritime