National Research Foundation - 2nd grant call on Scenario-based CRP
Underwater Infrastructure and Underwater City of the Future
Research Team Leaders:
Chu Jian, Susanto Teng and Tan Soon Keat
New approach to space creation
In land scarce Singapore, space creation is a key strategic area that concerns the survivability and Sustainability of the Nation. For this purpose, new and innovative ideas and technologies for space Creation must be explored and developed as one of the top priority for Singapore.
At the present, the following three approaches have been adopted for space creation:
- Going up using high-rise buildings
- Going down using underground caverns
- Expanding laterally through offshore reclamation
We have reached almost the limit for the first approach. For the second approach, it is only feasible when the geological conditions of the site are favourable and thus is restricted. Furthermore, the construction of caverns and the subsequent operational costs can be high. For the third approach, we have reached a water depth of 30 m or more. The costs involved and the fill materials required for reclamation in deep water escalate exponentially. There is also a severe shortage of fill materials for reclamation. Therefore, the existing offshore reclamation method is not sustainable or economically viable in the long run.
The research team have proposed a new approach – going underwater, that is, to make use of the sea space to construct underwater infrastructure and at the same time use the top-side of the infrastructures as reclaimed land. Many large diameter oil tanks have been constructed on reclaimed land in Southern Island and Jurong Island. Caverns are also being built in Jurong in rocks deep below the seabed for the same purpose.
If we can move the oil tanks down and bring the caverns up to occupy the sea space above the seabed, we have solved not only the problem with oil storage, but also the problem with fill materials for reclamation. Using this method, most of the underwater space has been occupied by the large size structures, as shown in Fig. 1. These large size structures themselves provide space for storage and infrastructure.
Therefore, the proposed approach kills two birds using one stone. More importantly, we no longer need to rely on other countries to import fill materials for land reclamation. The proposed method allows us to use our limited space even more efficiently. A large amount of land space that would otherwise be occupied by oil tanks, container ports, storage yards or factories can now be freed and used for other developments. We can also avoid the expensive cavern construction and save the underground space for more important use in the future.