Waste-To-Energy Plants: Properties and Operation

 This article explores the strengths of waste-to-energy (WtE) plants and highlights the differences between WtE facilities and traditional incinerators, emphasizing their advantages in terms of sustainability and emission reduction.

What is a Waste-to-Energy Plant?

A waste-to-energy (WtE) plant is a facility that converts non-recyclable waste into electricity and thermal energy.

In essence, waste is incinerated, and the heat generated from combustion is used to produce electricity or hot water.

These plants play a key role in waste management, offering a more sustainable and valuable alternative for the disposal of residual waste.

The recovery and reuse of waste materials are central to this process, making WtE technology a potential solution for reducing environmental impact and supporting the transition to a circular economy.

The WtE process generates high-pressure steam by heating water in a boiler until it boils.

This steam drives a turbine, converting thermal energy into mechanical energy, which is then transformed into electrical energy through a generator (alternator).

Additionally, the outgoing steam can be used to power heat exchangers for district heating networks.

The process begins when waste is transported to the plant and deposited into a mixing and storage pit. From there, it is loaded into the boiler for energy recovery.

Combustion produces heat, which generates high-pressure steam. This is then directed into a turbogenerator to produce electricity.

Waste-to-energy facilities are equipped with emission control systems that significantly reduce pollutants and purify flue gases before they are released into the atmosphere.

Differences Between Waste-to-Energy Plants and Incinerators

An incinerator is an industrial facility that disposes of waste through high-temperature combustion, typically between 850°C and 1050°C.

There are four main types of incinerators: grate-fired, fluidized bed, rotary kiln, and multi-stage hearth systems.

These facilities are used to dispose of both municipal and special waste.

However, a major concern with incinerators is the release of harmful emissions such as dioxins, furans, ash, and fine particulates.

In contrast, waste-to-energy plants are considered “second-generation” systems.

While they also rely on combustion, they are designed to recover the heat generated and use it to produce steam for energy production.

The most important differences between WtE plants and incinerators lie in emissions control and energy recovery capabilities.

In addition, WtE facilities are often capable of powering district heating networks—centralized systems that distribute heat to residential areas, providing a highly efficient energy-saving solution.

Waste-to-Energy Plants in Italy and Europe: Data and Pollution Levels

According to estimates by ISPRA (the Italian Institute for Environmental Protection and Research), there are around 40 waste incineration plants in Italy, unevenly distributed across the country.

More than 60% of these are located in Northern Italy, in regions such as Lombardy, Emilia-Romagna, Veneto, Piedmont, Trentino, and Friuli-Venezia Giulia.

In Central Italy, only eight are operational, mainly in Tuscany and Lazio, while the South hosts seven, with none in Sicily or Abruzzo.

Across Europe, there are over 350 waste-to-energy or incineration plants operating in 18 countries.

A significant share of waste is incinerated, especially in Central and Northern Europe, including Germany, Sweden, Denmark, and the Netherlands.

The thick white smoke seen coming from the cooling towers is often misunderstood.

In reality, this is mostly water vapor—a natural result of the cooling process after steam passes through the turbine.

Due to lower ambient temperatures and subsequent condensation, these plumes appear denser and are more visible from long distances.

Before being released into the environment, the exhaust gases are treated through bag filters to remove dust particles.

The smoke may contain chlorine, sodium, zinc, lead, magnesium, copper, aluminum, and chromium.

But are these emissions harmful to humans?

In-depth qualitative sampling would be necessary to assess health risks.
"So far, monitoring has focused mainly on quantitative analysis of particulate matter, without distinguishing between emission sources.
This highlights the need for qualitative measurements capable of identifying specific markers unique to each emission source."