Key pillar for Singapore’s sustained water supply-
Singapore’s demand for water is currently met through four sources – reservoir water, imported water from the Johor river in Malaysia, reclaimed water which is branded as NEWater and desalinated water. These sources are also called the Four National Taps of Singapore. Among the four sources, desalinated water is the key pillar of Singapore’s sustained water supply strategy. As the island region is surrounded by sea, desalinated water bolsters the reliability of water supply against prolonged periods of dry spells and droughts. However, with the increasing population in the country, the demand is set to increase. At present, the water demand of the country stands at about 430 million gallons per day (mgd) and it is expected to double by the year 2060. Non-domestic water demand or industrial water usage is also estimated to make up 70 per cent of overall water use by 2060. In light of the expected increase in demand, the Public Utility Board (PUB), Singapore, is creating additional water supply infrastructure while construction of desalination plants in the country is another effort in this regard.
Existing desalination infrastructure
PUB opened its first desalination plant called the SingSpring Desalination Plant in Tuas in September 2005. This seawater reverse osmosis plant produces 30 mgd of water to meet about 10 per cent of Singapore’s water needs. A second and larger desalination plant with a capacity of 70 mgd is the Tuaspring Desalination Plant. This plant, also situated in Tuas, commenced in September 2013. Both the plants can meet up to 25 per cent of Singapore’s current water demand. To boost the drought resilience of the country, PUB is in the process of constructing two more desalination plants at Tuas and Marina East. These plants will have a capacity to supply 30 mgd of water each and are expected to meet up to 30 per cent of Singapore’s water needs by 2060. The construction work on the third Tuas desalination plant commenced in 2016 and is expected to be completed soon. Construction of the fourth plant in Marina East commenced in June 2017 and is expected to be completed by 2020.
Fifth desalination plant at Jurong island
With the expected increase in water demand by 2060, PUB has proposed to execute a fifth desalination plant in the city at Jurong island on a public-private partnership (PPP) basis. The plant, expected to cost $282.28 million, aims to meet up to 30 per cent of the water demand in the city. To execute the project, PUB had selected CH2M Hill Singapore Pte Limited as the detailed design consultant in August 2016. Later, the bids for constructing the plant on a design-build-own-operate basis were invited on February 7, 2017. Four firms – Keppel Infrastructure Holdings Pte Limited, Sembcorp Utilities Pte Limited, Tuas Power Limited, and YTL Power International Berhad – were shortlisted under the pre-qualification stage. Following this, on September 27, 2017, a consortium of Tuas Power Limited and Singapore Technologies Marine Limited (TP-STM) emerged as the preferred bidder to build the plant. Later, for its execution, a concession company called TP-STM Water Resources Pte Limited was formed on October 31, 2017. Singapore Technologies Marine holds a 40 per cent stake in the concession company, while, Tuas Power holds the remaining 60 per cent stake. ST Marine has already injected its proportional share of equity amounting to $1.8 million into the capital of the concession company.
On November 6, 2017, a water purchase agreement was signed between TP-STM Water Resources Pte Limited and PUB. According to the agreement, PUB will purchase water at a tariff of 91 cents per cubic metre for the first year and the consortium is required to supply treated water for a period of 25-year starting from 2020.
The seawater reverse osmosis desalination plant will be situated next to Tuas Power’s existing Tembusu multi-utility complex so as to derive synergies in resources such as seawater intake and outfall structures, and energy from the in-plant generation facilities.
The engineering, procurement and construction contract for the plant is yet to be awarded. Once construction starts, it is expected to be completed in 2020 and will add approximately 0.02 million cubic metres of water per day to the nation’s water supply.
Other desalination plant
Besides the existing infrastructure, PUB is engaged in developing a unique dual-mode desalination plant (world’s first), also called the Keppel Marina East Desalination Plant or the fourth desalination plant. The contract for executing the 30 mgd capacity plant was awarded to Keppel Infrastructure Holdings Pte Limited on a design-build-own-operate model. The ground-breaking ceremony for the same was conducted in July 2017. The plant involves a large-scale dual-mode desalination process to treat both seawater and freshwater (Marina reservoir) depending on wet or dry weather conditions. This unique feature will help reduce plant energy usage when fresh water is available in abundance. Besides housing the plant, the facility will also feature a green public recreational space, including 215,278 square feet open green rooftop and rainwater harvesting structure for irrigating plants.
Recently, ABB has been tasked with the work of installing electrical, instrumentation, automation and control systems for the plant. The contract for the same was awarded in January 2018. Once completed, the desalination plant will be capable of generating 137,000 million cubic metres per day of clean water and will meet up to 30 per cent of the water demand by 2060.
The way forward
The continued and persistent efforts of PUB at achieving total water self-sufficiency by developing new projects will help ensure continuation of Singapore’s water success story. However, much of the success also depends on PUB’s ability to stay at the cutting edge of water sector technology advancements and being able to attract innovation and ideas from the best global minds and players. Alongside new projects and initiatives, PUB has to augment existing water resources by harvesting rainwater. Further, keeping in view the challenges such as climate change, rising energy costs, population growth and increasing urbanisation, PUB requires innovative solutions, and research and development (R&D) is the key to achieving a robust, affordable and sustainable water supply. With water demand expected to more than double by 2060, continual investment in R&D to seek more cost-effective and efficient ways of treating, recycling and supplying water is vital.
