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The Elektrana-Toplana Zagreb power plant (EL-TO Zagreb power plant) located in Trešnjevka, Zagreb, Croatia, is being modernised by replacing unit A of the plant with a new combined-cycle co-generation unit.
Hrvatska elektroprivreda (HEP), Croatia’s national energy company, is undertaking the project with an estimated investment of €214.7m (approximately $249m).
The unit will be capable of generating electricity and heat energy simultaneously. With an electrical output of 150MW and heat output of 114MW, the plant is estimated to produce 675GW of electricity, 450GW of heat, and 160GW of process steam a year.
Construction of the unit is expected to begin in 2018, with completion anticipated by the end of 2021.
The unit will create a reliable electricity source for the Croatian power system and significantly minimise CO2 emissions. It will have a high operational efficiency of 90% net.
Elektrana-Toplana Zagreb power plant Unit A make-up
The combined-cycle power unit will be equipped with two gas turbines, two heat recovery steam generators (HRSG), and one extraction back-pressure steam turbine.
Each gas turbine, combined with a generator, will have a nominal output of 50.5MW. The HRSGs will generate super-heated steam by using hot flue gases at the gas turbine exit.
With two extractions and a nominal output of 35MW, the steam turbine will be capable of operating in electricity generation and co-generation mode.
The cooling system of the plant will comprise air-cooled heat exchangers, divided into two sections. The first section will be used for cooling the steam from the steam turbine, especially during the hottest time of the year, while the other will be used for cooling certain systems of the plant such as electric generators, lubricating oil system, and feed pumps.
The combined-cycle unit will include a main operation building, a cooling system with auxiliary equipment, and a central control room and electric power facility.
The main operation building will be located in the western part of the EL-TO Zagreb power plant. It will have an engine room containing two gas turbines with associated diffusers, a boiler room with 60m-high stacks, and a steam turbine engine room.
The existing gas metering-reduction station and heating station will be reconstructed, the 110kV switchyard will be extended, and new building structures will be constructed.
Power transmission from Elektrana-Toplana Zagreb power plant
Electricity generated from the new unit will be transported to the electric transmission network via the existing EL-TO 110kV switchgear.
Process steam will be used for industrial needs, while generated heat will be used in the district heating system (DHS) of Zagreb city.
European Bank for Reconstruction and Development (EBRD) and a syndicate of commercial banks are providing a €87m ($100m) loan facility for the construction of the new co-generation unit.
European Investment Bank (EIB) is also supporting the project by providing a €43m ($49.7m) loan facility. The loan is guaranteed by the European Fund for Strategic Investment (EFSI), the main holder of the European Commission’s Juncker Plan, which was initiated to finance a greater number of riskier projects.
In July 2018, HEP awarded the engineering, procurement and construction contract and long-term service agreement to FATA, an Italy-based company and a member of the Danieli Group.
EL-TO Zagreb power plant unit A background
The EL-TO Zagreb power plant is primarily intended for heat generation, while electricity is also generated in the process.
Unit A of EL-TO Zagreb was commissioned in 1970 and has been generating electricity with a nominal output of 11MW.
Heat generated at the plant is delivered to consumers either through the district heating system of Zagreb City in the form of hot water or through a steam pipeline system as process steam for steam heating consumption.
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