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Zero emission vessels - Reduce emission in Ports

Waterborne transport greenhouse gas (GHG) emissions are on the rise, and they represent today almost 3% of global GHG emissions [1]. Ships entering EU ports emit 13% of the total EU transport GHG emissions [2], while inland waterway transport in the EU is estimated to emit 3.8 million tonnes of CO2 emissions per year [3]. Apart from GHG emissions, shipping is responsible for water degradation, air pollution and noise pollution. All these impacts have a negative impact on cities and their inhabitants.  

The International Maritime Organization (IMO), the United Nations agency focusing on waterborne transport, has developed an initial strategy on the reduction of GHG emissions from ships [5]. The strategy presents several measures to achieve its aims, including optimization of logistic chains and their planning, focus on power supply from renewable sources and development of infrastructure to support supply of alternative fuels and innovative technologies to further enhance the energy efficiency of ships. 

The European Commission is contributing to the task with several initiatives. The EU Maritime transport strategy 2009-2018 [8] included a set of environmental objectives for international shipping, such as the reduction of GHG emissions, NOx, and SOx, and the promotion of alternative fuels in ports. The roadmap for a resource efficient transport system set an objective of 40% reduction for EU CO2 emissions from maritime transport by 2050 compared to 2005 levels [9]. In the framework of the European Green Deal, EU climate target plans include the introduction of a high share of alternative fuels, such as renewable and low carbon liquid fuels [10]. To enable the uptake of alternative fuels, the Commission proposed a regulation requiring ports to address the demand for decarbonised fuels. At the same time, docked ships will be required to use shore-side electricity [11]. 

The Partnership Proposal for Zero-Emission Waterborne Transport focuses on six parallel activities, covering the use of sustainable alternative fuels, electrification, energy efficiency, design and retrofitting, digital green, and ports [4]. Also, the Clean Hydrogen Partnership [12] covers research on hydrogen and fuel cells for maritime applications, e.g. development and validation of a vessel running on liquid hydrogen (l, m), a vessel for hydrogen storage (n) or fuel cells, and hydrogen technologies developed for ports (o). Finally, energy-efficient and zero-emission vessels are also one of out of the five main topics of European waterborne transport research in H2020 [6]. Their successful deployment cannot happen without support from port cities.  

Within the framework of Mission Innovation, an industry roadmap for zero-emission shipping was developed. Three main pillars are considered the foundation for a zero-emission shipping future: ships, fuels, and fuelling infrastructure [7]. The latter is the most important, from the perspective of cities. 

The biggest potential for the reduction of emissions from waterborne transport is a transition towards a new generation of fuels and the preparation of appropriate fuelling infrastructure. There are several potential alternative fuels that can lead toward zero-emission vessels, including hydrogen and ammonia. These fuels can be used either in combustion engines (for long-distance shipping) or in fuel cells combined with electric motors (for shorter distances) [2]. Depending on the type of waterborne transport different solutions are necessary [4]: 

  • ferries – the most suitable option for waterborne transport electrification, since they operate between fixed points in a limited range. Apart from battery packs, fuel cells and internal combustion engines powered by alternative fuels might be also used as an energy source; 

  • short sea shipping – vessels that operate in a range of up to 200 nautical miles should enable to use battery packs, fuel cells, hybrid propulsion systems with electric and alternative fuels as well as propulsion systems using on-board renewable energy sources - as an individual energy source or in a combination of them; 

  • inland waterway transport – limited range and operation with easily available recharging and refueling infrastructure enable to implement and test a wide variety of zero-emission solutions. Temporarily, as a transition phase, for currently operating vessels, retrofitting and usage of HVO (Hydrotreated Vegetable Oil, produced from renewable and sustainably sourced vegetable fats and oils) might be considered; 

  • long-distance, international cargo ships, offshore vessels, and cruise ships - they mostly operate far from ports, nevertheless several solutions can be applied to reduce the impact on the environment (air, water, and noise pollutions), including in the vicinity of cities. Their high energy requirements make their transition towards zero-emission the most challenging but also necessary in the nearest future. Options include alternative fuels, electric and hybrid engines, renewable energies, etc. 

Regardless of solutions implemented for particular vessels, all relevant infrastructure (for recharging, refuelling etc.) in ports needs to be prepared and all the operations needs to be managed according to specific needs for new types of vessels. 


Zero emission vessels are currently during various stages of TRL, depending on particular solution applied. There are electric ferries already in use, which can replace vessels currently used within and between cities. They are designed for short distance, inshore applications and but similar solutions can also be used for inland waterway transport. They have a potential to be used for last mile delivery in cities with system of navigable waterways as they may help to reduce congestion.  

Among innovative solutions for zero emission vessels, the use of Liquefied Biogas is ready for commercial deployment but its usage is still extremely low [4]. The use of other potential alternative fuels, such as ammonia and methanol, is still at the demonstration phase. 

The strategic targets of the Partnership for Zero-Mission Waterborne Transport are also during the ‘demonstration’ level with time window until 2030 (2050 for long-distance ships), showing that more work needs to be done until proposed solutions will be available on the market.  For example, LEANSHIP project (d) took research achievements from previous European projects and put them into demonstration phase to prepare developed solutions for large-scale market uptake.  

The general aim of Partnership for Zero-Mission Waterborne Transport [4] is to provide and demonstrate zero-emission solutions for all main ship types and services before 2030, which will enable zero-emission waterborne transport before 2050. However, considering maturity level of existing solutions, one of the main challenges to achieve this aim are the long-lasting service and lifespan of ships (the average age of seagoing ship is about 21 years) [4]. This makes any change towards more energy efficient and zero emissions vessels a long lasting task, making any radical change very difficult if possible. Thus, any solution which helps to reduce emissions needs to be deployed as soon as possible. They should be deployed however, in a way that offer the highest possible interoperability. This is to avoid situation that an emission-reduction solution deployed in a ship is not compatible e.g. in another ports or other vessels, or if further, more efficient solutions which are now in a lower phase of TRL, become available. 

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