“Losing my future is not like losing an election, or a few points on the stock market,” said 9-year-old Severn Cullis-Suzuki at the UN Earth Summit in 1992. ‘The Speech that Silenced the World for Five Minutes’ still strikes a chord as the effects of climate change batter the world.

The island state of Singapore is particularly vulnerable. While the resource-scarce nation has found ways to thrive by developing its own water source and building upwards, climate change may be its greatest challenge yet.

Chong Mien Ling, Chief Sustainability Officer at the nation’s water agency PUB, shares how it combats climate change while continuing to meet the country’s water needs.

Going zero carbon by mimicking nature

PUB aims to reach net zero emissions by mid-century, reveals Chong. The agency is researching methods to remove carbon from its water treatment processes to achieve this.

A partnership between PUB and the University of California, Los Angeles mimics the natural process of carbon dioxide gas dissolving in seawater to form seashells. They combined dissolved gas with metals to create limestone and magnesite – the same materials that make up seashells.

These materials can then be safely disposed of or released into waterways. It is a permanent solution that uses less energy, is more efficient, and cheaper than trapping carbon dioxide gas, explains Chong.

Additionally, PUB is working alongside A*STAR’s Institute of Chemical and Engineering Sciences (ICES) to remove carbon dioxide from renewable fuels. These fuels are created from wastewater in its treatment plants.

The process uses aqueous ammonia, which absorbs more carbon dioxide gas and is less corrosive than traditional chemicals, highlights Prof Yeoh Lean Weng, Chief Sustainability Officer at A*STAR and Executive Committee Member, ICES.

This helps equipment to last longer, he adds.

These projects are part of PUB’s Carbon Zero Grand Challenge, which was launched in October 2021. The Challenge awards SG$6.5 million to innovations that help PUB achieve its net zero goals.

“Without the luxury of space as a small country, it is important to think creatively and embrace technology,” says Chong. This challenge will help PUB do just that.

Waste not, want not: Becoming energy self-sufficient

Another way PUB reduces its carbon footprint is through resource circularity, where the byproduct and waste materials of one facility becomes a resource for another.

PUB achieves this through the Tuas Nexus programme – the world’s first energy self-sufficient integrated waste and water treatment facility.

In the Nexus, food waste is used to increase production of renewable fuels at the water reclamation plant. This increases production by 40 per cent as compared to using waste water alone.

The fuel boosts electricity generation for the Nexus, with excess energy being exported to the grid. The programme is a collaboration with the National Environment Agency.

Powering up with clean energy

PUB also seeks to replace its current energy sources with cleaner energy. The agency has been trialling the use of floating solar panels, shares Chong. These panels allow PUB to use its large reservoirs to both capture water and generate electricity.

For example, the Sembcorp Tengeh Floating Solar Farm generates enough clean energy to power PUB’s five local water treatment plants. This reduces Singapore’s annual carbon emissions by about 32 kilotonnes, equivalent to removing 7000 cars off the roads.

Floating solar farms allow Singapore to install solar panels at a large scale, which would otherwise be difficult due to the country’s dense urban landscape and limited land space, Chong notes.

The agency is currently testing the possibility of setting up two other floating solar farms at Lower Seletar and Pandan Reservoir.

Reducing energy consumption in water treatment

Next, PUB is researching ways to reduce its energy consumption. They expect to remove approximately 60 per cent of total emissions from their water treatment processes by mid-century, says Chong.

Singapore primarily treats seawater by filtering salt through synthetic membranes, but alternative materials may reduce the energy needed for this process.

For example, PUB is developing ultra-permeable membranes which can potentially reduce the energy needed to treat seawater by 50 per cent or more.

Another technology the agency is exploring is ceramic membranes, which are more energy- and cost-efficient. They last four times longer than traditional membranes and reduce water loss which often occurs as a result of water treatment.

PUB also established the Keppel Marina East Desalination Plant – a facility that treats both fresh and seawater. The plant treats freshwater during rainy weather instead of seawater, reducing the overall energy needed to produce drinking water in Singapore, notes Chong.

“You are deciding what kind of a world we are growing up in,” Cullis-Suzuki concluded in her impassioned speech. The future may prove more optimistic than Cullis-Suzuki envisioned if more national agencies do their part to preserve this world for the generations to come.