Energy recovery is a proven, environmentally friendly way of diverting waste from landfill, creating electricity from the process.
Waste is thermally treated with resultant energy recovered to create heat. The heat energy is converted to steam energy which powers a turbine and generates electricity.
Waste to energy is successfully used around the world with more than 520 facilities operating in Europe, including in cities like Copenhagen and Paris.
When waste arrives at the facility, it is first inspected for compliance with the environmental permit and suitability for combustion in the plant then mixed by a crane to ensure a homogeneous waste supply. The waste then enters a boiler for combustion and resultant energy is recovered to create heat. The heat energy is converted to steam energy which powers a turbine and generates electricity.
Remnant ash produced during this process is then treated, with the metals removed for recycling and re-use. Any emissions are also treated to remove pollutants which are stored for disposal or re-use.
The energy recovery process reduces carbon emissions in three ways:
- Reduces landfill: Less landfill means less greenhouse gases, including methane, being released into the atmosphere from decomposing waste.
- Generates green energy: Each tonne of waste produces about 700 kilowatts-per-hour of electricity which is exported to the power grid. This means less electricity needs to be produced by fossil fuel sources like coal.
- Opportunity to recycle: Metal scrap in the waste is reclaimed and reused in the steel industry, and the ash created as a by-product of the combustion process can be used in construction.
More than 99.9 per cent of emissions are components of normal air like steam, oxygen, nitrogen and carbon dioxide.
For the very small remainder of emissions, those compounds go through a sophisticated treatment processes which ensures emissions remain well below all relevant standards.
There are two types of ash that result from the thermal treatment process:
- Bottom ash, which is solid residue that is discharged from the bottom of the furnace, and
- APCr (Air Pollution Control residue), which is created when the fly ash particles (from the furnace) are treated with lime and activated carbon and are captured in the purification process.
Bottom ash produced during the energy recovery process is treated, metals are removed for recycling and the remaining residue is re-used for inert road and construction materials.
Kwinana Energy Recovery are exploring ways to turn APCr into a product that can be used in cement product which would mean it can be recycled. Bottom ash is commonly used in the UK for road aggregate, and APCr can be used in construction.
Energy recovery is for general waste only. Energy recovery facilities are not licenced to take and process waste that can be recycled or composted.
The City of Kwinana provides a yellow top recycling bin for materials that should be recycled such as glass, cardboard, paper, cans and hard plastic containers and will roll out a garden organics bin in 2025 to increase recovery of compostable garden waste. For large green waste and bulk items the City provides a verge collection service.
Energy recovery facilities are a vital component of an efficient waste management system, offering a more sustainable alternative to landfill disposal.
In the current economy waste generation is inevitable, the goal to improve the system is to extract as much value as possible. Therefore recycling and composting is the preferred and better method, but when materials cannot be recycled or composted, converting waste into energy is the next best option. This process of energy recovery should only be considered after exhaustive efforts in source separation, composting and recycling have been applied.
These facilities are designed to handle residual waste, which is what remains after all recyclable and organic materials have been separated. This includes waste from households and commercial entities that have already undergone thorough sorting.
It’s important to note, that not all waste can be processed in these facilities. Items such as batteries, gas bottles, tires, medical waste, foam, vinyl, and large metal objects are excluded because they pose safety risks to infrastructure or could degrade the quality of the energy conversion process.