The plant consists of two identical simple cycle gas turbine units powered by diesel by and an emergency generator. Each unit has a "basic" continuous installed gross capacity of 90 MW and a peak capacity of 95 MW, and is made up of the gas turbine, a three-phase synchronous generator, a coaxial alternator and 15/160 kV step-up transformers. The exhaust fumes are released from the plant by means of two 18m high chimneys. The electricity is fed into the grid at a voltage of 150 kV.
On 21 December 2015 the new AIA Decree Authorisation was adopted for the Assemini plant authorising, for 5 more years, the operation of the two gas turbine units for the synchronous compensation network service, black start and emergency restart, introducing new, significantly lower, emission concentration limits and new mass emission limits on the flows of macro-pollutants.
To achieve the new emission limits, the integrated use of primary NOx reduction systems will be used, using water injection, and IGV valve adjustment (air flow control) for reducing CO, in addition to the combustion of fuel with very low sulphur levels.
The publication of the new decree for the AIA review of the Assemini plant and admission to the “Essenzialità” regime for 2016 allow a stable and sustainable future in terms of finance and authorisations over the subsequent five years.
The two gas turbine groups are currently used almost exclusively for the supply – by using alternators as "compensatory" engines – of the power factor correction service for the network.