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How PUB is to achieve net zero emissions

  • How PUB is to achieve net zero emissions
  • Launch of S$6.5 million Carbon Zero Grand Challenge to remove emissions from water treatment processes

About the entity

PUB Singapore's National Water Agency
PUB is a statutory board under the Ministry of the Environment and Water Resources. It is the national water agency that manages Singapore’s water supply, water catchment and used water in an integrated way.


Having successfully closed the water loop by recycling used water that greatly boosted the nation's water security nearly two decades ago, PUB, Singapore's National Water Agency, is now turning its eyes to close the carbon loop for ensuring water sustainability and also contributing to a low-carbon future.

In addition to the current suite of initiatives and research that PUB is already actively pursuing to reduce its carbon footprint, it has now launched a “Carbon Zero Grand Challenge" that offers attractive prize funding for game-changing solutions that are capable of removing carbon emissions from water treatment facilities. 

Carbon Zero Grand Challenge

Hosted on HeroX, the leading platform and open marketplace for crowdsourced solutions, PUB's “Carbon Zero Grand Challenge" is seeking carbon capture, utilisation, and storage (CCUS) and removal solutions from around the global and beyond the water sector. A total of S$6.5 million (US$4.8 million) will be awarded for innovative solutions that can help achieve PUB's net-zero goals by mid-century.

PUB Chief Sustainability Officer, Chong Mien Ling said, “Sustainability has always been at the core of PUB's work – we have diversified Singapore's water sources through its Four National Taps strategy and manage the entire water system in an integrated manner. As we grapple with the challenges of climate change, it is imperative that we continue to ensure that Singapore's water supply remains resilient but also sustainable. With water demand projected to almost double by 2060, the energy required to produce water is also expected to quadruple if we continue business-as-usual."

“Our ambition is to achieve net zero emissions by mid-century and we have mapped out a strategy to close the carbon loop by using more clean renewable energy and reducing the energy consumption of PUB's water treatment processes. Without the luxury of space as a small country, it is important to think creatively and embrace technology. Through this open innovation challenge, we are inviting researchers and companies from around the world to co-create carbon sequestration and utilisation technologies that can be integrated with PUB's operations. We hope to see game-changing solutions that can meet the operational needs of water utilities, while at the same time, capable of reducing carbon emissions." 

Three-pronged Strategy to Close Carbon Loop – Replace, Reduce, Remove

To ensure sustainable operations, PUB has been actively replacing carbon-based energy sources with solar photovoltaic (PV) systems deployed on facility rooftops and reservoirs over the years. There is also ongoing research and use of new technologies to improve energy efficiency and reduce energy required for water treatment processes. With these efforts, we expect to abate approximately 600 kt CO2e/year or 60% of total emissions by mid-century.

Capturing and removing carbon that we release into the atmosphere is the next big task on hand. PUB is already studying new technologies such as CCUS and carbon removal solutions that can be integrated with our water treatment facilities, to remove the remaining 40% or 400 kt CO2e/year of emissions.

Replacing Carbon-based Energy Sources with Solar Power

Following the opening of the Sembcorp Tengeh Floating Solar Farm in July this year, one of the world's largest in-land floating solar farms at 60 megawatt-peak (MWp), two smaller-scale floating solar farms at Bedok and Lower Seletar Reservoir have also commenced operations. These two floating solar farms at about 1.8hectares in size, are able to generate 1.5MWp each. PUB currently harvests some 70 MWp solar power from both its land-based installations and floating solar photovoltaic (PV) systems which can offset 8% of PUB's annual energy needs. 

PUB will be conducting feasibility studies next year for two other large-scale floating solar PV systems at Lower Seletar (100MWp) and Pandan Reservoirs (44MWp). We will continue to explore and assess suitable sites and facilities to deploy solar PV systems in an environmentally-sensitive manner.

Reducing Carbon Emissions

Water treatment processes to desalinate sea water and recycle used water to produce NEWater are energy-intensive. PUB has been working with industries and research institutes to develop and test next-generation membranes that can substantially reduce the energy required by 50% or more. We are also constructing energy self-sufficient water reclamation plant (Tuas Nexus) that can utilise rich carbon content in used water to produce more biogas for electricity generation. On the demand side, we continue to push for water conservation and water recycling among households and industries.

PUB is progressively replacing its diesel-powered vehicles with Electric Vehicles (EV) to do its part in reducing energy consumption and emissions, in line with Singapore's vision to phase out vehicles with internal combustion engines (ICE) and have all vehicles run on cleaner energy by 2040. The first batch of six EVs will be deployed from November this year

Removing Carbon Emissions

Carbon removal is an emerging technology focus area and PUB has already started two projects with A*STAR's Institute of Chemical and Engineering Sciences (ICES) and University of California, Los Angeles (UCLA) to advance our work in this area. With UCLA, we are exploring the use of electrolysis technology to capture carbon dioxide in seawater to form solid carbonates and hydrogen, as well as a softened stream of seawater that can be desalinated at lower energy. We are also working with ICES to explore the feasibility of removing carbon dioxide from biogas and carbonising it with waste materials (e.g. incinerated ash to produce aggregates or alternative sand) which can potentially be used in the building construction industry or land reclamation applications. The “Carbon Zero Grand Challenge" aims to identify more such game-changing ideas from around the world that can be integrated within water facilities within the next decade. 

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