The port and maritime shipping industry have unique forms of circularity. Both shipping lines and terminal operators rely on their linear supply/procurement chains, with the outcomes being the setting up of shipping networks (A) and investments in port infrastructure (B). Four principles common to the circular economy can be integrated into the port and shipping sectors:
- Maintenance. This basic form of circularity ensures that the product can be recurrently used and have its life cycle extended. To maintain acceptable operational conditions, both ships (A.1) and ports (B.1) require recurring maintenance. For capital-intensive assets, maintenance is a common aspect of extending their life cycle, in opposition to several consumer goods not designed to be repaired. Therefore, the port and shipping industry are based on substantial repair and maintenance practices where cost-effectiveness and predictability are at the forefront of their commercial viability. Maintenance is a particularly challenging issue for port terminals as operations have to continue while maintenance is taking place.
- Reuse. There is an extensive market for ship sales or leases (A.2), allowing shipping assets to be shared and remain optimally used. For instance, several of the largest shipping lines can lease more than half of their ship assets. At the end of the lease, the ship can return to the leasing market and be “reused”. Another circular characteristic concerns the cascading of ships from deepsea to regional feeder services when new and larger ships are introduced. Since ports are fixed assets, concessions (B.2) can be perceived as circularity mechanisms where port authorities offer terminal assets to be leased. Once the concession is over, the terminal asset can be leased by another terminal operator. Terminal equipment can also be leased to cover periods of high activity or to remove excess capacity.
- Remanufacture. Ships can be converted to new uses and new propulsion technologies (A.3). For instance, the first containerships were converted bulk and break-bulk ships, and the first cruise ships were converted liners. Low sulfur bunker fuel requirements implemented in 2020 are inciting many shipping lines to reconvert their ship engines with technologies such as scrubbers. In the port sector, changing the function or operational characteristics of a port terminal by upgrading the existing equipment (B.3) is a form of circularity. For instance, cranes and yard equipment can be upgraded for automation.
- Recycle. There is an extensive industry that scraps ships and recycles their components, particularly metals (A.4). India and Bangladesh are the most significant locations where ships are scrapped. Once at the end of its life cycle, terminal equipment can be discarded and recycled (B.4). A more complex issue concerns the land footprint of a terminal that can be converted for other uses, such as residential. For instance, if the nautical profile of the terminal is no longer suitable for port operations (lack of depth), the site can be “recycled” into urban redevelopments.
Containers represent a specialized form of circularity as container shipping is designed as a recycling system. A container is a reusable unit constantly being repositioned by carriers who own or lease container fleets. Another segment involves container leasing companies allocating their assets to maximize returns. Thus, the container is an interchangeable transport unit, with its carrying capacity being traded on transport markets. To remain a suitable asset for carriers, containers need to be cleaned, maintained, and repaired. At the end of their useful life (about 15 years), containers can be discarded and recycled for their components or other uses (e.g. storage, office space).