Singapore is a country with no natural water resources. The country has always worked towards ensuring a sustainable water supply for its citizens and protecting its coastline from rising sea levels. The Public Utilities Board (PUB) of Singapore launched an SGD 6.5 million “Carbon Zero” Grand Challenge in October 2021 to eliminate carbon emissions from its water treatment facilities and achieve net zero emissions by mid-century and scale to water facilities across the world. PUB is looking for carbon capture, utilisation, removal and other technologies that can be incorporated into its operations and scale up to commercial size within a decade or less.


Singapore has always been an innovator and a leader in developing clean, efficient, and cost-effective energy, water and environmental solutions owing to the serious water challenges the country faces. PUB, the statutory board under the Ministry of Sustainability and the Environment of Singapore, manages the country’s water supply, water catchment and used water in an integrated way. It is in charge of overseeing and regulating the country’s complete water supply system, which includes water catchment, drainage, waterworks, water reclamation facilities and sewage systems. PUB was also designated Singapore’s National Coastal Protection Agency in April 2020 and has undertaken the responsibility of protecting the country’s coastline. Over the last four decades, PUB’s watershed management and treatment procedures have provided a continuous supply of clean, high quality water for the country. The Intergovernmental Panel on Climate Change’s sixth assessment report, released in August 2021, has stated that immediate and robust action is required to keep global temperature rise below 2 °C, as committed to in the Paris Agreement. In a bid to contribute its bit to the climate, PUB to set a target of achieving net zero carbon emissions by mid-century. According to PUB’s Sustainability Report 2020-21, Singapore’s emissions in 2020 stood at 467.6 kt carbon dioxide equivalent (CO2e).

The organisation is set to meet 80 per cent of the country’s total water demand through its NEWater and desalination facilities. PUB is already working to minimise its carbon footprint by installing solar photovoltaic (PV) on facility rooftops and at reservoirs to replace carbon-emitting energy sources, as well as decreasing carbon emissions through energy efficiency, reduced desalination energy and conservation. By mid-century, these activities are predicted to reduce carbon dioxide emissions by around 600 kt CO2e per year. While current initiatives can significantly lower PUB’s future carbon footprint, the organisation is looking for ways to remove an additional 400 kt CO2e per year from its facilities, which would require solutions such as carbon capture, utilisation and storage (CCUS), and carbon removal.

PUB’s projected Scope 1 emissions that will require new solutions (200 kt CO2e per year) are associated with its four water reclamation facilities. The remaining Scope 2 emissions (200 kt CO2e per year) are due to the electricity used to power PUB’s facilities, for example, water treatment plants, desalination plants, NEWater factories and used water-treatment plants.


With the aim of reducing its emissions by 60 per cent or 600 kt CO2e per year by the middle of this century, Singapore has undertaken many efforts.These include replacing carbon-based energy sources with solar PV systems at reservoirs and facility rooftops. It has also implemented new technologies which boost energy efficiency and reduce energy use in water treatment processes. PUB now gathers 70 MW peak of solar energy from both land-based and floating solar PV systems, enough to provide 8 per cent of the utility’s annual energy demand and it expects to cut at least 60 per cent of its emissions by the middle of the century through its ongoing efforts. Further, it is constructing an energy self-sufficient water reclamation plant (Tuas Nexus) that can utilise rich carbon content in used water to produce more biogas for electricity generation.

In the future, PUB aims to remove the remaining 40 per cent through CCUS and carbon removal solutions that can be integrated with its water treatment facilities. It is also been working with industries and research institutes to develop and test next-generation membranes which can reduce energy requirements in desalination and water recycling by 50 per cent or more.

The challenge

The carbon zero grand challenge will be hosted on crowdsourcing platform HeroX, and will seek out solutions from around the world and beyond the water sector. It aims to address emissions associated with PUB’s water treatment facilities and to keep the global temperature rises below 2 °C. The solutions that can be taken into consideration are CCUS technologies that can be integrated with PUB’s water treatment or desalination operations, address greenhouse gas (GHG) emissions associated with PUB’s facilities, removal of carbon dioxide integrated with PUB’s operation from the atmosphere and seawater.

The challenge is part of PUB’s strategy to prevent water demand from doubling. Through proof of concept (PoC) and an initial field demonstration, it will focus on expediting the development of innovative concepts. The challenge will include two phases of competition and a pilot-scale demonstration over approximately 45 months. In the initial phase, up to six proposals will be awarded SGD 250,000 each to develop a PoC. In the PoC phase, solvers will showcase how their ideas or solutions could be integrated within PUB’s operations through a desktop simulation and/or lab-scale study and develop a detailed design for a pilot project. After this phase, up to two proposals will be awarded SGD 2.5 million each to demonstrate an approximately 1 kt-scale version of their solution at a PUB facility in Singapore and develop a plan to achieve commercial scale within a decade or sooner. This challenge excludes solutions that do not directly cut or eliminate GHG emissions related with PUB’s water facilities. It seeks to focus the attention of innovators, investors and thought leaders on water sector emissions in order to accelerate the deployment of innovative solutions to address Singapore’s net zero carbon emission goals

The proposals will be submitted till February 24, 2022. It will last for nearly 45 months in total, with the two competition phases lasting about 21 months each and the pilot project lasting about 24 months. PUB is encouraging researchers and companies from all over the world to co-create on carbon sequestration and utilisation technologies that can be incorporated into PUB’s operations through this open innovation challenge.

Summing up

The carbon zero grand challenge, worth SGD 6.5 million (roughly $4.8 million), aims to encourage creative solutions that can enable PUB reach net zero emissions and help scale these solutions to water facilities across the world. It is looking for solutions that can be incorporated into PUB’s operations at any technological readiness level. Even though the worldwide water industry generates around 5 per cent of GHG emissions, it has garnered little attention in climate debates. Despite the fact that Singapore’s local water sector emissions account for less than1 per cent of the city-state’s emissions, any attempt to cut carbon emissions helps to combat climate change and should be encouraged. PUB’s specific net zero aims will be addressed by ideal solutions through this challenge, which will also be applicable to water facilities across the world. By doing its bit, the country aims to maintain resilient water supply and ensure that its water treatment remains efficient and sustainable.