Waste-to-energy plant: operation, pros and cons

Waste-to-energy plant: operation, pros and cons

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Waste-to-energy plant, also called incinerator, is an industrial plant that eliminates waste by burning it and with the heat produced by this combustion produces energy. It is therefore a full-fledged combustion system, consisting of an oven, where the waste is burned, a boiler, in which there is water then heated with the heat produced, and a turbine that is driven by steam. produced by heating the water and thus transforming thethermal energy into electrical energy.

Waste-to-energy plant: operation

The operation of a waste-to-energy plant it can be easily explained in stages, step by step, almost following the path of matter and energy, from incoming waste to outgoing electricity. The waste collected "around", far or near is a variant discussed, they are stored and deposited with a crane in the furnace where combustion takes place at temperatures that can reach and exceed 1000 ° C. To maintain these levels it may happen that you enter of the methane gas.

After the combustion phase in the Waste-to-energy plant steam is produced, this occurs in the downstream boiler: the water contained there, with the heat obtained by burning the waste, evaporates. How does electricity come out? The steam obtained from the boiler reaches and sets in motion a turbine which, coupled to a gear motor and alternator, transforms thethermal energy into electrical energy. Here she is! But we're not done.

The Waste-to-energy plant has not finished: there is the phase of extraction of the ashes, which constitute about 30% by weight of the incoming waste, while filter systems they try to intercept, as technology allows, the fine dust which in turn is about 4% of the weight of the incoming waste. Ashes and dust, are both disposed of in landfills for special waste, the hot fumes pass through a multi-stage filtering system where they are treated and then released into the atmosphere at about 140 ° C.

Difference between waste-to-energy plants, incinerators and landfills

On the terms, also on the terms, they were born discussions, around the Waste-to-energy plant, as well as the opportunity that it represents, or not, for our country and in general for an industrialized and polluted country. The term "waste-to-energy plant " can be seen as alluring to the concept of valorisation of waste, when in truth it is not a question of enhancing the garbage because if you do the math you can clearly see that the incineration process - from the collection to the disposal of the ashes - it consumes much more energy than is necessary for the reuse process - from recycling to recycling.

On the other hand "Waste-to-energy plant”Can be seen in terms of energy production and therefore as an enhancement of waste as source of energy. An interpretation supported by those who support these plants, to which it should be noted that the energy production process includes the release into the atmosphere of pollutants consisting of very fine nanoparticles that get out of control. They are so thin because the temperature is very high, as we have already said, and to get an idea of ​​the quantities, 70% of the waste introduced is eliminated, the remaining 30% becomes a "bad" nanoparticle.

Waste-to-energy plant: pros and cons

Before making an overview of the various positions regarding the Waste-to-energy plant, let's take a look at its diffusion in Italy and Europe. In our country from 2001 to 2012 the amount of municipal waste sent to a Waste-to-energy plant it's passed from 2.5 million tons to 5.5, today about 70% of the “tricolor” waste is incinerated in plants in Northern Italy.

That of Waste-to-energy plant remains not in first place among the disposal methods used in Italy, we are on average with the rest of the continent in which, however, there are cases Waste-to-energy plant-free. Greece, Cyprus, Latvia, Romania and Bulgaria do not use it and Slovenia, Malta, Lithuania and Croatia very little. On the contrary, countries like Sweden, Switzerland, Denmark and Germany make extensive use of Waste-to-energy plant, one of the largest in Europe is located in the Netherlands, a nation that is however aimed at maximum prevention of waste production or its recycling and reuse.

As promised we explore the opinions pros and cons on Italian soil. Between against waste-to-energy plant there is Legambiente which argues that it prevents a virtuous waste management, represented primarily by good circular economy practices, furthermore given that the production of municipal solid waste has been decreasing for years, according to the association there are all the technological solutions to focus on the recovery of matter and recycling.

Also Italian biologists, taking an example from the “Asm model” of Brescia, they explain that the Waste-to-energy plant "It indefinitely produces enormous quantities of waste, is the enemy of separate waste collection, of the Kyoto protocol", it also involves waste and creates problems for emissions into the environment. They call it black on white “one wrong machine for waste treatment, inefficient from an energy and economic point of view ".

For the 5 Star Movement, another enemy of Waste-to-energy plant, the danger of fine dust looms: "In fact, it has now been established that incinerators, especially the latest generation ones, produce very high quantities of ultra-fine dust and nano-particles with high carcinogenic power, not interceptible even by the most modern filters ”he says.

On the side of the "Yes" to the waste-to-energy plant There is the Renzi government which gave the green light to 2 new ones Waste-to-energy plants in Sicily approved in the State-Regions Conference. To speak is the Minister of the Environment Gian Luca Galletti explaining how this choice "breaks the principle of self-sufficiency of waste disposal at the regional level and creates a single national disposal network". The Waste-to-energy plant it also serves "to counter the EU infringements to which Italy is exposed" explains the minister inviting "all regions to seize the objective of prevention of waste generation by 10 percent“.

Of the same opinionWaste-to-energy plant is Alexander Beulcke, president of Allea - Energy Festival, which compares our Italy with the many countries of northern Europe where there are few “cons”: it is an “all cultural gap” because there are “the same horizons and the same technologies. And the same regulatory context is the European one. According to Beulcke in Italy on the subject Waste-to-energy plant there is "a chaotic patchwork of information held together by one profound lack of trust and from fear. Bridging this gap is now a priority ”. Since "we won't stop producing waste" we might as well "turn them into a resource reducing the amount of waste, recycling as much as possible, recovering energy "with the highest priority of" drastically reducing the amount of waste that ends up in landfills ".

Waste-to-energy plant: Amager Bakke

Let's go back to looking at the Waste-to-energy plants others, and there is a special one arriving by autumn 2016 in Copenhagen, on which the Danes are hoping to ski and have fun as a 180 meter black run, a blue of 55 and a green of 150 will be built on the roof. Amager Bakke waste-to-energy plant (ARC) and it will burn about 400 thousand tons of waste every year producing electricity and hot water to heat homes and offices, taking Denmark one step further towards the goal of 100% energy self-sufficiency by 2050.

Zero harmful gases from this Waste-to-energy plant, while the combustion residues will be recycled for construction and agriculture, the nitrogen oxides emitted as a result of combustion will be reduced as well as CO2 and each ton less of CO2 will be marked with a light ring from a huge fireplace that stands out over the Waste-to-energy plant himself to flaunt its green efficiency. The plant was designed by a team headed byarchitect Bjarke Ingels, will be able to obtain 25% more energy from waste, ranking among the most ecological and efficient plants in the world.

Waste-to-energy plant: Acerra

After this out-of-bounds exploit, let's go back to a known one Waste-to-energy plant of our home but always among the most important in Europe: that of Acerra which extends over 9 hectares of surface, disposing of 600,000 tons of urban waste per year to transform it into about 600 million Kilowatt hours of electric energy able to power 200,000 households. The emission values ​​of this Waste-to-energy plant are more than 50% lower than the limits set by the European Directives.

Waste-to-energy plant: Milan

Even the Milan of Expo 2015 has its own Waste-to-energy plant and has it from long before Expo. Is called Silla 2, is near Figino and in 2003 he was also awarded by the Milan Triennale with the Gold Medal for Italian Architecture for private clients. This Waste-to-energy plant is an excellent example of energy valorisation of residual waste downstream of separate collection, capable of cogenerate electricity and heat for district heating.

To get an idea, adjectives aside, at full capacity Silla 2 heats over 20,000 families, starting with those in the Gallaratese district and the Rho-Pero Fair, up to users in the neighboring area if connected to district heating. In addition to heating, it produces electricity and meets the annual consumption of 130,000 families, without neglecting the safety and sustainability side: the Waste-to-energy plant is equipped with sophisticated systems of emissions analysis who monitor them continuously 24 hours a day.

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Video: How a waste-to-energy plant works (October 2022).