The Jury of the Prize for the Scientific Article of the Quarter of the Higher Technical School of Engineering, recognizing the high quality of all the publications in competition, after the appropriate deliberations in which criteria based on several bibliometric indicators are taken into account, has unanimously decided of its components, award the ETSI Scientific Article of the Quarter Award: October-December 2021, to the following work: “Techno-economic and operational assessment of concentrated solar power plants with a dual supporting system”, Applied Energy, vol. 302, November 2021, developed by Raúl Ernesto Gutiérrez Álvarez, Pedro García Haro and Alberto Gómez Barea. DOI 10.1016/j.apenergy.2021.117600

Although concentrated solar thermal power (CSP) plants are commercial technologies, their larger-scale deployment has been limited in recent years due to their high investment costs and greater complexity relative to other technologies. However, the role that these systems can play as renewable providers of dispatchable electricity may be crucial for the decarbonization of future electricity grids. It is expected that the auxiliary services that dispatchable renewable energy plants can provide to the electrical system will favor a greater participation of intermittent and lower cost renewable technologies such as solar photovoltaic and wind power.

Due to their ability to have thermal energy storage (TES) systems, CSP plants are capable of generating electricity when the sun sets, avoiding for a few hours the need to operate natural gas combined cycle plants. However, in order to operate as base load plants, CSP plants require additional support systems to the TES that can be managed, but maintaining their renewable nature. In this sense, the hybridization between CSP and biomass conversion systems emerges as an interesting alternative to increase, on the one hand, the performance of CSP plants and, on the other hand, alleviate the risks associated with the consumption of large quantities of biomass in bioenergy plants.

A detailed analysis of the benefits of integrating a fully renewable dual backup system (based on biomass and thermal energy storage) in CSP plants is presented in our study. The solar resource of Seville and two plants of 50 MWe capacity each, based on parabolic trough and solar tower technologies, have been taken as case studies. In both cases with the integration of a biomass boiler and with a hybridization mode in parallel to the power block. In addition, 7 operating strategies for the biomass boiler have been proposed and modeled in combination with 5 capacity levels for the thermal storage system (from 0 to 20 hours). Finally, the Analytical Hierarchical Process (AHP) methodology was used as a multi-criteria decision tool to comparatively evaluate the technical, economic and operational performance of all the proposed cases.

The results show that the participation of backup biomass favors the operation of the system as a base load plant, increasing the capacity factor (CF) by up to 71%, the net electrical efficiency by up to 10%, and reducing the cost. generation by up to 56%, compared to autonomous CSP plants. For the considered solar resource (Seville), reasonable generation costs (0.153 USD/kWh) can be achieved for a balanced compensation between biomass and TES, while allowing a firm energy supply (CF ≥ 80%) and reducing the flexibility required of the boiler. The inclusion of large TES capacities reduces the annual demand for biomass by half and accentuates the seasonal complementarity between solar and biomass resources. Finally, CSP plants with a dual backup system represent a promising option for locations where solar and biomass resources are moderately available.

This award is financed by a Grant for Scientific Dissemination Activities from the VII Own Research and Transfer Plan of the University of Seville.