PUB plans to increase renewable energy sources to achieve net zero emissions

Launch of S$6.5 million Carbon Zero Grand Challenge to remove emissions from water treatment processes.

Lower Seletar Reservoir floating solar farm.

Having closed the water loop by recycling used water that enhanced the nation’s water security nearly two decades ago, PUB, Singapore’s national water agency, has now turned 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 has already pursued to reduce its carbon footprint, it has now launched a Carbon Zero Grand Challenge that offers prize funding for game-changing solutions that are capable of removing carbon emissions from water treatment facilities.

Hosted on HeroX, the platform and open marketplace for crowdsourced solutions, PUB’s Carbon Zero Grand Challenge attempts to seek 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.

Chong Mien Ling, CSO for PUB, commented: “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.”

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, PUB expects to abate approximately 600kt CO2e/year or 60% of total emissions by mid-century.

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

Replacing carbon-based energy sources with solar power
Following the opening of the Sembcorp Tengeh Floating Solar Farm this July, one of the world’s largest in-land floating solar farms at 60MWp, two smaller-scale floating solar farms at Bedok and Lower Seletar Reservoir have also commenced operations. These two floating solar farms at about 1.8 hectares in size, are able to generate 1.5MWp each.

PUB currently harvests some 70MWp solar power from both its land-based installations and floating solar PV systems which can offset 8% of PUB’s annual energy needs. The water agency will subsequently conduct feasibility studies next year for two other floating solar PV systems at Lower Seletar and Pandan Reservoirs, and 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 seawater 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. The agency has also been constructing energy self-sufficient water reclamation plant, such as Tuas Nexus, that can utilise rich carbon content in used water to produce more biogas for electricity generation. On the demand side, PUB will continue to push for water conservation and water recycling among households and industries.

PUB has progressively replaced its diesel-powered vehicles with electric vehicles (EVs) as a part of reducing its 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 started two projects with A*STAR Institute of Chemical and Engineering Sciences (ICES) and University of California, Los Angeles (ULCA) to advance its work in this area. With ULCA, PUB plans to explore 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.

PUB also worked with ICES to explore the feasibility of removing carbon dioxide from biogas and carbonising it with waste materials 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 and within the next decade.