S’pore’s water challenge: More on tap at lower carbon costs

From solar farms to carbon capture, PUB is looking at all ways and means to meet rising demand for water while keeping down carbon emissions.

- Asit K. Biswas and Pang Chee Meng

How “green” is the glass of water you drink?

The question captures in essence the challenge Singapore faces – it needs to ensure long-term water security while keeping a lid on the cost to the environment in terms of carbon emissions.

In practical terms, consider the fact that while Newater and desalinated water have made Singapore less reliant on rain for its water supply, they are also more energy intensive to produce.

As the national water agency, PUB has to take into account Singapore’s broader and longer-term climate change goals in managing the water supply. Specifically, it has to meet its target of peak carbon emissions by 2025 and strive to achieve net-zero carbon emissions by or around mid-century.

Currently, PUB emits about 460 kilotonnes of carbon dioxide equivalent per year (ktCO2e/yr). But with Singapore’s water demand projected to double from now to year 2060, emissions are also expected to rise steadily to the one megatonne mark. About 200 ktCO2e/yr of this will come from direct emissions from the treatment of used water. Electricity used to power PUB’s installations, such as waterworks, desalination plants, water reclamation plants and Newater factories, contributes to emissions indirectly.

To meet its net-zero carbon goals, PUB has formulated a three-pronged strategy to replace carbon, reduce carbon and remove carbon. It plans to use more renewable energy in place of fossil fuels (“replace”), cut energy consumption from all parts of its operation (“reduce”), and develop new technologies to capture carbon dioxide from the environment (“remove”).