Wind powered Thermal Energy Systems (WTES) - A techno-economic assessment of different configurations

Abstract

In this thesis different WTES concepts, which can be developed with commercially available devices, are techno-economically assessed focusing on the conversion of wind power into heat and the following thermal storage. No reconversion of heat into electricity is considered. Firstly, five different heat generation concepts for WTES are investigated based on literature research: electric boiler (EB), electrical driven HP (eHP), mechanical driven HP (mHP), retarder (RET) and absorption HP (AHP). Three different system sizes, as far as final heat demand is concerned, are analysed: 23.6 MWh/yr – 11,800 MWh/yr – 118,000 MWh/yr. Furthermore, the five WTES concepts are ranked based on the Levelized Cost of thermal Energy (LCOEHEAT) taking into account their average Capital Expenditures (CAPEX) and Operational Expenditures (OPEX), also considering different capacity factors (CF) and a life span of 20 years. On top of that, in order to develop cost intervals for each concept and, therefore, analyse possible costs deviations, two different scenarios for each technology are assumed: Maximum scenario, which accounts for the maximum CAPEX and OPEX reviewed, and Minimum scenario, which accounts for the minimum CAPEX and OPEX reviewed. Moreover, an additional analysis for large systems is performed regarding the LCOEHEAT variation as function of the distance between the WTES windfarm and the final heat demand and it aims to analyse the maximum distance cost-achievable. Every analysis developed within this thesis is compared with traditional heat generation sources so as to estimate the economic feasibility of the WTES. Finally, results show that small system presents remarkably higher LCOE when compared with medium/large systems, mainly drive by its more than 3 times higher capital expenditures (CAPEX) and, small system’s most cost-convenient WTES technology is mHP which presents lower LCOE along the entire CF spectrum. As far as medium and large system is concerned, both system sizes present promising heat generation costs, as far as LCOE is concerned. They differ only in the fact that large system presents lower costs manly drive by the economies of scale considered. Furthermore, it is interesting to point out that in large systems when CFs lower than 0.25 are considered, RET technology presents LCEO which are slightly higher (15%) than those obtained by mHP. Moreover, all technologies can be considered as cost-effective alternatives, even when low CFs are analysed.