Assessment of the economics of fusion energy as a key element of a future sustainable energy mix

In order to be able to evaluate, from an economic point of view, under which conditions fusion technology can be a key element of a future electricity generation system, adequate calculation tools are needed to simulate a fusion reactor in a simple way and calculate the cost of electricity generated. Other tools are required to simulate an energy system, composed of different power plants, and to evaluate the system cost of electricity. The thesis work begins with the presentation of the FRESCO code (Fusion REactor Simplified COst): a code developed in C ++ language with the aim to model in a simplified way a D-T fusion power plant based on the tokamak configuration. In FRESCO the power plant is studied from a technical and an economical point of view. It allows the users to calculate reactor parameters i.e. geometrical and physical dimension of the power plant, electromagnetic parameters of the machine, net electricity production, auxiliary energy needed, the operative cycle phases (especially for the pulsed configuration), and not last, the related capital cost and the cost of electricity. As part of the thesis work, the improvements introduced in FRESCO are presented first, such as the model of the reactor chamber vacuum pumping system, and the integration between the FRESCO code and an optimization program based on genetic algorithms. Then, the analysis of the effects of the duration of the operative phases in a pulsed power plant on the cost of electricity is presented. In the second part of the thesis, the COMESE code (COsto MEdio del Sistema Elettrico, Average Cost of the Electric System) is described. The code developed as a part of the doctoral research activities, is used to develop and test energy scenarios. In particular, scenarios that can show how nuclear fusion technology can be part of the electricity generation park. The COMESE C ++ calculation code uses the electricity demand and generation data of a country, together with the data of the technologies and storage systems, in order to simulate an energy scenario. It allows to evaluate if the hypothesized generation succeeds in satisfying the demand. In that case, it calculates the levelized cost of timely electricity (LCOTE) for the scenario. It also offers the possibility to perform a stochastic analysis, based on the Monte Carlo method, in order to take into account the uncertainty on the economic parameters of generation technologies. An application of the COMESE C ++ code is presented. Two fully renewable European energy scenarios, one for Northern Europe based on the wind generation technology and one for Southern Europe based on photovoltaic generation technologies, are studied and compared. Alternative scenarios including fusion technology were developed, in order to estimate which economic conditions (overnight cost) fusion power plants can be competitive and bring a benefit to the levelized cost of timely electricity of an energy scenario.