Upgrading of the Sant Adrià de Besòs waste-to-energy plant

The Sant Adrià de Besòs waste-to-energy (WtE) plant was built and commissioned in 1975, when it was the first facility of its kind in Spain. The plant has been in operation with excellent uptime for 40 years, thanks to the different upgrading work carried out over that period. The latest renovation work started in 2008 with a view to creating a state-of-the-art combustion system. The project, which sought to adapt the waste-to-energy plant to the new Catalonian municipal waste management model, was completed in 2014.

TERSA is a publicly owned company whose shareholders are the Barcelona City Council (58.64%) and the Área Metropolitana de Barcelona (41.36%). It serves the 36 municipalities of the AMB (including the city of Barcelona), which have a total population of around 3.2 million. One of TERSA’s main social missions is the treatment of municipal waste generated in this area through energy recovery.

The Sant Adrià de Besòs plant treats approximately 25% of the waste generated in the Área Metropolitana de Barcelona (AMB). The waste treated is the reject from the mechanicalbiological treatment plants (ecoparques) and is the approximate equivalent of the waste generated by a population of 800,000
in one year. Waste-to-energy is a process of controlled combustion that gives rise to thermal and electrical energy, valorisable materials (ferrous and non-ferrous metals, and rare earth elements) and ash (considered a special waste). It is also a process that enables a very significant reduction in the initial weight and volume of the waste.

The energy generated is considered to come from a renewable source. It is exported to the electricity grid and sold under free electricity market conditions.

Moreover, since 2003, the WtE plant has also supplied thermal energy, in the form of water vapour, to the district heating and cooling distribution network that serves the districts of Fórum and 22@ in Barcelona, for heating, air conditioning and domestic hot water applications.

New catalan municipal waste management model

Energy recovery is an option proposed by the European Union to avail of reject that cannot be recycled or reused in an efficient, eco-friendly manner. The Waste Framework Directive 2008/98/ EC, transposed into Spanish law by Act 22/2011 of July 28th on waste and contaminated land, sets out the following waste management hierarchy: Prevention, preparation for reuse, recycling, energy recovery and disposal. In accordance with this legislation, the new municipal waste management model adopted by the Catalan Waste Agency proposes energy recovery only for waste known as reject, which cannot be reused or recycled.

Therefore, the rest fraction, the fraction of household waste obtained from nonselective collection, must be treated in mechanical-biological treatment plants to recover all valuable materials prior to the implementation of energy recovery.

This change has resulted in a significant increase in the net calorific value (NCV) of the waste treated in the plant, which has risen from the previous range of 1,700 – 2,200 kcal/kg to a new range of range of 2,500 ± 600 kcal/kg for the current rest fraction.

As a result of these new waste characteristics, the Sant Adrià del Besòs WtE plant needed adjustment and modification for the purpose of maintaining mechanical treatment capacity, increasing energy efficiency and improving operation and maintenance.

Objectives

The Plan for the adaptation of the Waste-to-Energy Plant to the new Catalan municipal waste management model was a strategic plan with the following objectives:

• Adaptation of the waste-to-energy plant to the characteristics of the new waste from the mechanical and biological treatment plants in order to maintain nominal treatment capacity.
• Optimisation of energy production, adapting the the thermodynamic cycle to fully of the calorific value of this new waste.
• Increase available steam to supply energy to the heating and cooling distribution network serving the districts of Fórum and 22@ of Barcelona.
• Increased plant uptime, with a reduction in the duration of line and plant downtime for maintenance and/or review operations.

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Noelia Marcuello,  Plant Engineer

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Plant Report published in: FuturENVIRO March 2015