Sustainable Shipping 101

Now-a-day’s sustainability has become a critical factor in managing goods and services. For international shipping, sustainability is also a long term but a slow process. Holistic efforts are needed in the perspective of a ship instead to take fragmented efforts to achieve sustainable operation shipping. However, shipping is port-to-port service which makes the key issue in strategic planning. But communities around the world are now more concerned about climate change and sustainable development in following the sustainable development goals in the United Nations agenda 2030. Shipping became popular as a result of oil transport during the 20th century which led large oil discharge into the sea as the effects became visible by the time and need of safer and less destructive shipping was aimed. This led to the formation of the International Maritime Organization for more reliable navigation and to prevent accidental oil spilling in the sea. International Maritime Organization (IMO) that deals with international shipping integrated its efforts with sustainable development goals (SDG) for strategic goals of the organization of 2018-2023. It was agreed that by January 2020, all the ship-owners would comply with IMO global sulphur reduction strategy, fuel containing 0.5% of sulphur content while in emission control areas the fuel with 0.1% of sulphur content. IMOs strategic efforts have been regulated goal-based since the 2000s and comprehensive plans have been made. Though current shipping practices are also facing challenges to achieve sustainable development goals.  
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Why shipping needs exhaust treatment technologies?
As the international maritime shipping is increasing, there are more emissions and growing concerns related to human health and ocean ecosystem. About 80% of fuel used in shipping contained high sulphur content producing particulate matter, carbon compounds, NOx, SOx and many more during combustion. Many of these compounds having less residence time in the air attach tightly to the vessel and readily dissolve in the ocean surface. To achieve sustainability goals, greener technologies are developed to avoid the consequent effects of shipping. The most widely used compliance is exhaust gas cleaning systems which are commonly known as scrubbers. These systems remove sulphur from exhaust marine engines. These scrubbers are economically viable than low sulphur fuels and are also useful for ship-owners to invest.

Why are Cleaner technologies preferable than low Sulphur fuels?
The cost of residual fuel is 400 US dollar per tonne, while low sulphur fuels cost 600 US dollar depending on the port. As the 2020 global sulphur cap is implemented, the ships will have to comply with low sulphur fuels which are very costly. The alternative way to achieve a sustainable development goal is to find cost-effective and environmentally sound technologies. There is a larger financial attraction for using exhaust gas cleaning systems for those ships that consume a large amount of fuels also having the space to accommodate this equipment. It has 5 million US dollar cost of installing these scrubber systems which can be recovered within 2-3 years. It has been estimated that 2000 vessels with scrubbers would be fitted by 2020. According to the international chamber of shipping, the incorporation of scrubbers is increasing in major shipping companies, and this trend would increase up to 20% by 2020.

Available scrubbers
However, varieties of scrubbers are available like loop, closed-loop and hybrid systems.  Open-loop scrubbers which are effective in areas with low pH buffering capacity but efficiency are reduced in high-temperature water, and their alkalinity is managed by sodium hydroxide. In the closed-loop system, applied in freshwater, wash water after removing scrubbing products is pumped back to the system. They can also be applied at a limited discharge rate by using seawater. Hybrid systems can switch between open and closed-loop modes and wash water is collected in specific tanks which are disposed of in reception facilities in port. Currently, many ships use hybrid systems. An open-loop system is very easy to handle and require low maintenance and does not require any storage tank. But wash water, or scrubber sludge must be cleaned before release into seawater. Because directly entries of water wash into the sea is a real environmental concern. However, hybrid scrubbers are suitable for long and shortage voyage. Beside these wet scrubbers, dry scrubbers are also applicable which efficiently remove NOx and Sox from the exhaust gas.  

For these scrubbers system, the scrubbers waste must be collected and disposed offshore into specifically designed vicinity. These scrubbers have their benefits and maintenance requirement which must be installed according to the area of operation, ship schedule of the lease, space available, freshwater availability on board and availability of power to run system including many other various conditions.