## 3 Emission Reduction Measures at Ports
### Seaside  
Emissions from the seaside are mainly from seagoing vessels and support vessels (e.g., tugs, push-boats, tenders, fireboats, pilot boats, police boats). In many seaports, seagoing vessels are the main source of port emissions, which can account for up to 69% depending on the port characteristics [13]. Seaside vessel activities occur in five traffic areas: sailing in the area close to port, anchorage area, port basin, manoeuvring, and berthing [14]. GHG emissions are generated by a vessel's main and auxiliary engines in the first four traffic areas, whereas during the berthing period, the main engine is switched off and only the auxiliary engines are used. We summarise the relevant solution measures, including the cases and effects in Table 5, and explain these measures below. The operational measures to reduce vessel emissions at port areas include the following: slowing ship speed, just-in-time arrival, reducing port time, and training ship crew and port pilots. Slowing down the vessel speed is an effective way to reduce fuel consumption and therefore emissions; this measure has been widely adopted and documented, especially in the circumstances of vessel overcapacity in order to cut vessel fuel consumption cost. Slowing speed from 18-25 knots to 12 knots near the port would reduce the main engine load factor from 80% to 10% [15]. Vessel just-in-time arrival is also termed virtual arrival, which refers to the practice of the vessel slowing down in anticipation of the congestion and waiting at the next port of call. [PERSON] et al. [16] evaluated 5066 voyages by 483 very large crude carriers between 44 countries and estimated the emissions could be reduced by 7% to 19% if the just-in-time arrival measure were adopted. It is well-known that vessels spend a significant amount of time at ports. [PERSON] and [PERSON] [17] conducted a case study of a dry bulk carrier and reported that more than 40% of the vessel time was spent at ports and half of the time at ports was unproductive. They stated that even if only one to four hours of port time per port call could be reduced, the vessel energy usage would be reduced by 2-8%. [PERSON] et al. [18] examined the influence of ships' crew and ports pilots' qualification on ship manoeuvring time. They reported that appropriate education and training could reduce ship manoeuvring time significantly and reduce emissions from ships up to 12.5%. The technical measures to reduce emissions from vessels include the following: hull design (e.g., shape, material, coating), propulsion system (e.g., hybrid power, machinery, waste heat recovery), onshore power, and carbon capture and storage. Optimising the vessel dimensions and form may achieve 2-30% reduction in CO\({}_{2}\), and the use of lightweight materials could reduce CO\({}_{2}\) emission by 0.1-22% [19]. The adoption of hybrid electric auxiliary power and propulsion can reduce CO\({}_{2}\) emission by 2-45%; the use of waste heat recovery may achieve 1-20% CO\({}_{2}\) reduction [19]. Onshore power is also called cold-ironing. When vessels are docked at port, the vessel's diesel-fuelled auxiliary engines will provide power to maintain essential vessel functions such as lights, heating, and cooling. Onshore power refers to the process of providing electrical power from the shore supply to the docked vessel so that the vessel's auxiliary engines can be turned off. This practice can reduce CO\({}_{2}\) emissions by over 30% [15]. Carbon capture and storage (CCS) is the process of capturing CO\({}_{2}\) from emissions and then permanently storing them deep underground or utilising captured carbon to create other products. The Japanese shipping giant Mitsubishi Shipbuilding has developed a ship-based carbon capture system that can reduce ship emissions by up to 90% (www.potterclarkson.com, accessed on 10 December 2023).