How they work

• Waste to Energy plants incinerate waste disposed of as General Waste as well as waste sent for recycling that cannot be recycled. 
• These plants burn at ~850C. At this temperature, most organic materials are destroyed. Waste that is unable to be incinerated ends up as ash. The ash consists mostly of glass, stone, sand and metals. Waste like food, wood, paper, and plastics have little to no residual ash. 
• On average, incineration decreases the volume of waste by 90%.
• Residual ash from the incineration process is sent to Semakau landfill.
• Energy produced by these plants is used to power a steam turbine generator. The electricity produced this way is delivered to the grid.
• Fumes from the incineration process are “scrubbed” of toxins through various means so that the gas and water vapors released are clean. 

Criticisms

The major downside to burning waste is that it releases a lot of greenhouse gases (mostly as CO2). Waste sent straight to landfill works as a kind of “carbon sink”. But due to space constraints, it is essential that Singapore reduces the volume of waste by incineration. 

Toxins released from waste incineration are also a concern in places where they do not employ effective scrubbing solutions (older generation plants had this problem). However that is not an issue in Singapore.