The plant consists of two identical simple cycle gas turbine units and a diesel-powered emergency generator. Each unit has a "basic" continual rated capacity of 90 MW gross and a peak capacity of 95 MW, and is made up of the gas turbine, a three-phase synchronous generator, a coaxial alternator, 15/160 kV step-up transformers. The exhaust fumes are released from the plant by means of two 18 m high chimneys. The electricity is fed into the grid at a voltage of 150 kV.
On 21.12.2015 the new Decree Authorization AIA was adopted for the Assemini plant authorising, for 5 more years, operations of the two TG units for the synchronous compensation network service, black start and emergency restart, introducing new emission concentration limits significantly lower than the existing ones 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, as well as the combustion of fuel with very low level sulfur levels.
The publication of the new decree for the AIA review of the Assemini plant and admission to the Essentiality regime for 2016 allow a stable and sustainable future in terms of finance and authorisations over the next five years.
The two TG groups are currently used almost exclusively for the supply - by using alternators as "compensatory" engines – of the power factor of the network correction service.
On February 26, the Ministry of Environment and Territory and Sea Protection issued the decree of Integrated Environmental Authorisation (AIA) for the Assemini plant, authorising the operation of each gas turbine (GT) of the plant for a maximum 500 hours per year, until 26 February 2016.
Construction began following the Decree issued by the Ministry of Industry, Trade and Crafts on 2 July 1991 and the plant entered into service in 1992.
Plant construction was foreseen in the emergency plan proposed by Enel to the Interministerial Committee for Economic Planning in 1975.