SSF (Secondary Solid Fuel) - Buzzi Unicem Italia

SSF (Secondary Solid Fuel) is a waste disguised as fuel

False. Beyond the regulatory aspects that regulate it, from a technical and practical point of view it is not correct to define Secondary Solid Fuel (SSF) simply as a waste. In fact, this fuel is derived from a series of special physical and mechanical treatments of unsorted solid urban waste (SUW) that take place downstream of separate collection, increasing its value and making it possible to use it as a calorie carrier in a combustion system, the purpose of which is not the incineration of a waste but rather the manufacture of a product (cement). Indeed it allows a use that is an alternative to landfill disposal and incineration, exploiting a combustion process that takes place anyway for production purposes.

Then, from a regulatory point of view and in compliance with certain strict conditions established by Ministerial Decree no. 22 of 14 February 2013, thanks to these treatments the waste thus recovered ceases to be such and is recognized as a fuel as per Annex X of Part Five of Italian Legislative Decree 152/2006. In such cases, it is therefore the processing carried out on the waste that determines its transformation into a product.

The use of SSF is foreseen by the sector Best Available Techniques (BAT) and respects the EU waste hierarchy, downstream of recycling and material recovery. This use enables energy recovery prior to disposal in landfills.

Cofiring and SSF are contrary to European principles

False. The production and use of SSF comply with the EU's circular economy strategies and fully respect the waste hierarchy, both from the point of view of production and use.

The production of SSF is guaranteed by the following steps:

Aerobic bio-stabilization of waste to reduce the bacterial load and reduce its humidity by 20-25% (this means a reduction in the amount of waste to be treated).
Recovery of residual materials present in the undifferentiated SUW (Solid Urban Waste), primarily iron/metal and inert waste.
Removal of organic chlorine through selective infrared (NIR) systems.
Final shredding of the product to sizes of less than 30 mm to improve combustion and reduce the resulting emission load.

That same Commission Bulletin COM(2017)34 on waste energy recovery emphasized its fundamental role in the pursuit of a circular economy, inviting Member States to give due consideration to these aspects in addition to the priority forms of reuse (prevention, reuse and recycling).

The use of SSF is not consistent with the European waste hierarchy

False. The use of SSF in cement plants is fully in line with the waste hierarchy, which in fact provides for and encourages energy recovery, instead of disposing waste in landfills or incinerating it.

As also recognized by the European Court of Justice, the use of SSF as a fuel in cement kilns is a recovery activity and not a disposal.

Moreover, the energy recovery of a high quality SSF in cement kilns is more energy efficient than the thermal destruction of waste in a waste-to-energy system.

Furthermore, no ash or slag is generated that requires disposal in a landfill.

SSF cofiring is at odds with separate waste collection

False. The production of SSF is not at odds with separate waste collection as SSF is produced later, primarily from the share of properly treated unsorted waste.

Furthermore, in order to be used as fuel in cement plants, SSF must not contain materials such as glass, aluminum or plastic containing high values of chlorine (e.g. PVC), which could contribute to clogging certain parts of the plant during the production process. These materials therefore remain destined for recovery.

The use of this fraction of unsorted waste in the production of SSF allows a clear minimization of the amount of waste sent to landfills and enhances materials that are no longer recyclable.

Countries that use SSF cofiring do not encourage separate waste collection

False. In countries where the rates of separate waste collection are high, the use of landfills is minimal. In fact, in such countries there is an elevated use of waste-to-energy plants and SSF cofiring in cement plants.

In Europe, the countries that have high levels of separate collection and recycling have also increased the share of energy recovery for all those materials that are not yet recyclable (for example due to the lack of suitable technologies) or definitively no longer recoverable.

The two things are therefore not contradictory, indeed they are complementary, since SSF cofiring helps to close the cycle of separate collection, allocating only the portion of material that cannot be recovered as such to energy recovery.

SSF is more polluting than traditional fossil fuels

False. Years of SSF use, hundreds of tests and the continuous and discontinuous measurement of emissions in the stacks of cement plants both with and without SSF have demonstrated the substantial invariability of the emissions produced by this alternative fuel compared to traditional fossil fuels.

Moreover, certain emission parameters, such as nitrogen oxides (NO_x) and sulphur oxides (SO_x), tend to decrease due to the lower presence of nitrogen and molar sulphur in the SSF.

SSF combustion ashes make cement harmful

False. The use of SSF as fuel in cement plants does not generate any type of ash to be disposed of later.

The clinker burning process takes place at very high temperatures (with a flame at 2,000°C) at which the raw material and the fuel are transformed. All the raw materials and the heat produced – net of the emissions in the stack, which are always monitored – are transformed and incorporated into new silicate particles, called clinker.

The resulting cement, after grinding the clinker with gypsum, perfectly complies with the relevant European standards, no different from the cement produced using traditional fossil fuels (coal, lignite, pet coke or natural gas).