Nanyang Technological University's (NTU) waste-to-energy facility in Tuas South aims to convert the varsity's waste into valuable resources such as electricity, construction materials and useful metal alloys.

The $40 million facility, set up in May 2019, has processed 4,500 tonnes of rubbish so far.

The facility, which is capable of treating 11.5 tonnes of waste daily, takes in municipal waste from the NTU campus and other locations.

Unlike conventional mass burn incinerators, which operate at around 850 deg C, the NTU plant is able to heat up to 1,600 deg C. Its high temperature means it is able to turn rubbish into syngas - composed of mostly carbon monoxide and hydrogen - which is used to generate electricity.

The rubbish is also turned into recyclable metal alloys and slag - a glass-like material that can be used as a replacement for sand in concrete.

Some 85 per cent of the waste is converted into syngas, 12 per cent to slag and metal alloys, and the remaining 3 per cent into fly ash.

The slag is turned into NEWSand, a material that can be used in construction.

NEWSand can partially replace fine particles in concrete, and has been used in constructing a temporary concrete footpath at Our Tampines Hub and the new plaza in front of the Environment Building in Scotts Road.

Assistant Professor Grzegorz Lisak, director of the Residues, Resource and Reclamation Centre at NTU's Nanyang Environmental and Water Research Institute, told The Straits Times that the facility's exhaust flue gas, which contains carbon dioxide, is treated before being discharged as clean gas - containing mainly nitrogen - into the atmosphere.

But about 12 per cent of carbon dioxide is still leaked into the atmosphere.

Therefore, Prof Lisak's team is using ash to trap carbon dioxide in order to decarbonise the operations and get the facility to net-zero emissions.

"We are providing a testbed for this carbon capture technology, which can be applicable to other incineration plants," said Prof Lisak.

Cheryl Tan