Waste-to-Energy (WtE)

From waste to worth

Energy recovery from combustion

Energy recovery from the combustion of municipal solid waste (MSW) plays a pivotal role in the waste management hierarchy. This hierarchy categorizes various management strategies based on their environmental impact, from the most preferred to the least. Within this ranking, energy recovery is positioned below source reduction and recycling/reuse but stands above disposal.
Today, globally still 70% of the waste is disposed in landfills and dumpsites. On the other side, not all waste can be recycled or reused: think about contaminated waste, composite materials and post recycling waste. Waste to energy is a unique opportunity to recover resources and energy from non recyclable waste, and hence to divert them from disposal.
The process of confined and controlled burning, termed as combustion, serves a dual purpose. Firstly, it significantly reduces the volume of solid waste that would otherwise end up in landfills. Secondly, it harnesses energy from the waste burning process. This energy generation not only serves as an alternative energy source but also curtails carbon emissions. This reduction is achieved by offsetting the energy traditionally sourced from fossil fuels, knowing that the energy produced by waste to energy plant is considered 50 à 60% renewable due to the biogenic carbon content of non recyclable waste, and by minimizing methane production at landfills.

The waste transformation process

Upon arrival at an MSW combustion facility, the waste is offloaded from collection vehicles and stored in a designated trash bunker. An overhead crane is employed to mix consistently and subsequently feed the waste into the combustion furnace where waste is converted into energy: the combustion process releases heat, which is utilized to convert water into steam. This steam then drives a turbine generator, producing electricity. The steam can also be used as such in industrial processes or to feed a district heating network.
Post combustion, bottom ash is gathered for further treatment: ferrous- and non ferrous metals can be recovered and the mineral fraction can we reused as a road foundation substitute. Concurrently, ammonia, lime or bicarbonate and active carbon are injected into the flue gases to depollute them. The residues are collected in a high-efficiency baghouse filtering system. As the gas stream navigates through these filters, they effectively remove over 99% of particulate matter. The trapped fly ash particles are collected in hoppers and are then transported via an enclosed conveyor system to the ash discharger.The polluted resides are extracted from the cleaned flue gases at the outlet of the bagfilters. Those residues are sent to a class 1 landfill specifically designed to prevent groundwater- or soil contamination. The cleaned flue gases are released in the atmosphere via a stack.

Waste-to-Energy explained

Waste-to-Energy: A Sophisticated Simplicity. Discover the nuanced intricacies and clear-cut fundamentals of this innovative process through a series of enlightening videos, brought to you by our experts at Keppel Seghers.

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