Energetic assessment and economic design of an autonomous RES system for the electrochemical production of H2 from H2S Black Sea waters
Fylaki, Panagiota
This study assesses the perspective of hydrogen sulfide not only from an environmental but also from an economic point of view towards a hydrogen based economy for Black Sea adjacent countries. H2S is a poisonous and detrimental gas that has gradually led to environmental degradation in Black Sea waters for both flora and fauna species. To this end, its removal and further processing towards an advanced group of energy and chemical products is currently characterized of paramount importance for the environmental salvation of the wider coastal region. Regarding the economic point of view, by delivering to the surface H2S/H2O mixtures, extracting and further on decomposing them via the process of electrolysis, we can commercially exploit the hydrogen component as an excellent energy carrier in fuel cells. Further on, sulfur by-products are a valuable building component of a widely used chemical (sulfuric acid). ASPEN plus software has been utilized in this thesis, in order to approach two different methods of hydrogen sulfide extraction and sulfur compounds utilization. Their core difference lies on the way that each process flow-sheet exploits the SO2 (main by-product) towards H2SO4 production. Based on the two process flow-sheet comparative analysis, a series of advantages and disadvantages were reported and concluded to the prominent operating scheme. An interesting outcome however, is that both process designs require the same electrical energy for delivering ready-to-use H2S/H2O mixtures. Thus, another software tool was employed to design an autonomous renewable energy sources system in order to meet the demanding energetic needs. Via HOMER software, renewable forms of energy including solar and wind energy along with a conventional diesel generator, were utilized to provide the necessary energy requirements. By evaluating the meteorological conditions in Black Sea coastal region, three different base case scenarios and an optimal system configuration were proposed. The implementation of a photovoltaic installation in the coastal region of Turkey, a wind park in the coastal region of Romania and a combination of both solar and wind park in the coastal region of Bulgaria are going to be thoroughly examined. The variables of concern for the evaluation of the scenarios lie on the Net Present Cost, the annual operating cost and the levelized cost of energy. Core aim is to identify the lowest possible investment and operating costs with simultaneous full covering of the electrical demand. As was found the optimal scenario from an economic point of view, consists of a biogas generator along with solar and wind park installations in the coastal region of Bulgaria. The thermal requirements of the system are covered by a CH4 burner along with the excess electricity from the RES configuration.
