Incineration does not make waste disappear.
It changes the waste into a smaller set of outputs that Singapore can manage more efficiently.
Mixed incinerable refuse arrives at a Waste-to-Energy plant. The waste is burned at high temperature. The heat turns boiler water into superheated steam. Steam drives a turbogenerator and produces electricity. Flue gas passes through pollution-control equipment before release. Ferrous metal can be recovered from the ash. The remaining ash then leaves the plant for offshore landfilling at Semakau.
NEA states that Singapore currently operates four WTE plants: TuasOne Waste-To-Energy Plant, Keppel Seghers Tuas Waste-To-Energy Plant, Tuas South Incineration Plant and Senoko Waste-To-Energy Plant.
The main land-saving effect is volume. NEA states that incineration reduces solid waste to ash amounting to about 10% of the original volume.
The operating chain is: collection truck → weighbridge → refuse bunker → crane feed → furnace combustion → boiler steam → turbogenerator electricity → flue-gas cleaning → ash cooling and metal recovery → Tuas Marine Transfer Station → Semakau Landfill.
Quick answer: why incinerate waste in Singapore?
- Land saving: ash occupies about one-tenth of the original waste volume.
- Energy recovery: combustion heat produces steam and electricity.
- Sanitation: high-temperature treatment destroys much organic and biological material in mixed refuse.
- Metal recovery: ferrous metal can be recovered from the ash stream.
- Controlled emissions: flue gas passes through purpose-built treatment systems before discharge.
- Landfill preservation: only ash and non-incinerable waste occupy Singapore’s scarce landfill capacity.
1. Collection vehicles arrive with a measured load
Public and licensed waste collection vehicles carry incinerable refuse to the WTE plant.
The vehicle is weighed before and after unloading so the plant can determine how much waste was delivered.
The weighbridge converts a truck full of mixed material into an accountable disposal quantity before treatment begins.
2. The refuse bunker buffers an irregular city
Waste trucks arrive according to collection routes and traffic, not according to the exact second the furnace needs fuel.
A large bunker stores incoming refuse and separates truck arrival timing from furnace feed timing.
The plant can therefore maintain a more stable combustion process even when collection vehicles arrive in waves.
3. Negative pressure helps keep bunker odour inside
Mixed refuse contains food waste and other odorous material.
NEA states that the refuse bunker is maintained below atmospheric pressure so odorous air is less likely to escape into the surrounding environment.
That air can then be managed within the combustion and ventilation system rather than leaking uncontrolled through building openings.
4. Grab cranes mix and feed the waste
Household refuse is not a uniform fuel.
One load may contain wetter food waste while another contains more paper, plastics or dry combustible material.
Large grab cranes move refuse inside the bunker and feed it into the incinerator. Mixing helps reduce extreme variation before the waste enters the furnace.
5. The furnace operates at roughly 850–1,000°C
NEA states that Singapore WTE incinerators operate at temperatures between about 850°C and 1,000°C.
At those temperatures, combustible material oxidises and releases heat while the volume of solid material falls dramatically.
Refractory lining protects the furnace walls from sustained high heat and corrosive conditions.
6. Incineration is thermal treatment, not recycling
Burning a plastic item can recover part of its energy value.
It does not recover the plastic as plastic.
That is why Singapore’s waste hierarchy still places reduction, reuse and recycling upstream of disposal. WTE manages material that remains in the incinerable waste stream; it should not be confused with keeping materials circulating at their highest value.
7. The furnace releases heat that the boiler captures
Combustion creates hot flue gas.
Instead of allowing that heat to leave unused, the plant transfers much of it into boiler water and produces high-temperature, high-pressure steam.
The waste stream has now become an energy stream.
8. Steam drives a turbogenerator
Superheated steam expands through a turbine.
The turbine spins an electrical generator, converting thermal energy from waste combustion into electricity.
Part of the electricity supports the plant’s own operations and the balance can be exported to the grid according to the facility design and operating condition.
9. Electricity is a useful by-product, not the only reason the plant exists
A WTE plant is fundamentally part of Singapore’s solid-waste disposal system.
Its electricity output improves resource efficiency, but the plant still has to treat waste reliably even when the electricity market price is low.
The public service is disposal. Energy recovery reduces the cost and environmental wastefulness of performing that service.
10. Flue gas has to be cleaned before it leaves the stack
Combustion produces gases and fine particulate matter that cannot be released untreated.
NEA describes flue-gas cleaning systems that include electrostatic precipitators, lime dosing and catalytic bag-filter processes to remove dust and pollutants before discharge through the stack.
The WTE plant therefore contains an air-pollution-control plant inside the waste-treatment plant.
11. Air-pollution control does not mean zero emissions
Combustion cannot produce energy without generating exhaust gases.
The environmental objective is to control pollutants to the applicable regulatory standards through combustion management and flue-gas treatment.
A visible chimney therefore should not be interpreted as either proof of uncontrolled pollution or proof of zero pollution. The relevant question is what the gas contains after treatment and whether the plant complies with its emission requirements.
12. The solid output becomes ash
After combustible material has burned, mineral and non-combustible residues remain.
NEA states that the resulting ash occupies about 10% of the waste’s original volume.
This 90% volume reduction is the key land-saving advantage in a country where landfill space is exceptionally scarce.
13. Volume reduction is not mass annihilation
Much of the original carbon and other combustible material leaves the solid stream as gases after combustion and treatment.
Mineral material remains as ash.
It is therefore more accurate to say incineration greatly reduces the volume requiring landfill than to imagine 90% of the material simply ceased to exist.
14. Ferrous metal can be recovered from the ash stream
Metal objects can survive combustion in recoverable form.
NEA states that ferrous scrap is recovered from incineration ash and recycled.
This is a second resource-recovery route after electricity: material that would otherwise occupy landfill volume is separated for metal recycling where technically and economically suitable.
15. Ash still needs a landfill
The WTE plant cannot be the final destination because ash remains.
Incineration ash is transported to Tuas Marine Transfer Station, loaded into barges and moved offshore to Semakau Landfill.
WTE therefore postpones landfill exhaustion by shrinking the waste volume; it does not abolish the landfill requirement.
16. Singapore has four WTE plants in 2026
NEA’s current infrastructure page lists TuasOne, Keppel Seghers Tuas, Tuas South and Senoko as the four operating WTE facilities.
The plants belong to different generations and ownership models, but together they form the national thermal-disposal backbone for incinerable refuse.
TuasOne was commissioned in 2021 and replaced the older Tuas Incineration Plant, which closed in February 2022 after 36 years of operation.
17. Waste treatment is moving toward Tuas integration
Singapore is developing the Integrated Waste Management Facility as part of Tuas Nexus beside PUB’s future Tuas Water Reclamation Plant.
The co-location allows waste and used-water processes to share selected energy and resource flows more effectively than if each facility operated in isolation.
The next generation therefore aims to improve not only incineration efficiency but system integration across waste and water treatment.
18. A worked example: one truck of mixed incinerable refuse
Imagine a collection vehicle arrives with a mixed load from several residential estates.
The vehicle is weighed, unloads into the bunker and is weighed again. Cranes mix and feed the refuse into the furnace. Combustion heats the boiler. Steam drives the turbogenerator. Flue gas is treated. Ash leaves the furnace at a fraction of the original volume. Ferrous metal is recovered where possible. The remaining ash is sent through Tuas Marine Transfer Station toward Semakau.
The truckload has become electricity, treated exhaust, recovered metal and a much smaller solid residue.
19. Common misconceptions
Misconception: Waste-to-energy means all waste becomes electricity.
No. only part of the combustion energy becomes electricity; gases and ash remain as other outputs.
Misconception: Incineration is recycling.
No. it is disposal with energy and some material recovery; upstream reuse and recycling preserve materials more directly.
Misconception: 90% volume reduction means 90% of the waste’s mass vanishes.
No. the 90% figure refers to disposal volume reduction, not simple mass disappearance.
Misconception: WTE eliminates the need for Semakau.
No. ash and non-incinerable waste still require landfill space.
Misconception: The chimney releases furnace gas untreated.
No. flue gas passes through pollution-control systems before release.
20. The deeper idea: WTE buys land with thermodynamics
Singapore cannot afford to bury every rubbish bag at its original volume.
Incineration uses high-temperature chemistry to convert bulky mixed waste into several smaller, more manageable streams. Heat becomes electricity. metals can be recovered. combustible material becomes treated gaseous products. the remaining minerals become ash.
The system’s most important product is not the electricity.
It is time for Singapore’s only landfill: one tonne of refuse still has environmental cost, but far less landfill volume reaches Semakau than if the same material were buried directly.