Modelling and evaluation of solar process heat integration on supply level

Heat consumed by industries, the so called process heat, amounts to around one fourth of the total European energy demand [1]. Currently the most of this heat is supplied burning fossil fuels [2]. The conversion of process heat to renewable energy sources has therefore a huge quantitative potential in terms of reduction of our dependence on fossil fuels. In this sense, one interesting option is to provide heat to industries exploiting solar energy, the so called solar process heat. The aim of this master thesis is the modelling and evaluation of the integration of solar process heat in industrial heat supply systems. At first it has been developed a model of a conventional industrial heat supply system, which consists of a boiler producing high pressure steam and a distribution net delivering the steam to the industrial processes. In order to find the most promising integrations of such a system with solar process heat, different configurations of solar thermal systems have been modelled. Several annual simulations have been accomplished, varying the location and the dimension of the solar thermal system. The results have been analysed from an energetic point of view, comparing the benefit of each configuration in terms of solar fraction and solar energy gain. It has been then performed an economic evaluation about the feasibility of the suggested integrations. The conclusion is that the two most promising integration points are pre heating of make-up water (using a storage) and direct steam generation. Make-up water pre heating exploits solar energy efficiently but can only supply a limited amount of heat (2,58% of the total heat demand). For this reason this integration is profitable only for supply networks with high make-up water mass flows, otherwise the solar thermal system is small and it specific costs are high. Direct steam generation instead can obtain a much higher solar fraction than make-up water pre heating but has lower efficiency due to minor diffuse radiation acceptance and no storage in the solar system. Therefore direct steam generation is profitable only if there is a large availability of DNI.