Search

This study assesses existing literature on radiative cooling through bibliometric and keyword analyses, shedding light on both quantitative and qualitative aspects of the subject. The research adheres to a systematic methodology, encompassing query formulation, data extraction, data curation, and analysis, accompanied by author interpretations and discussions. The evaluation encompasses the scrutiny of radiative cooling patents and scientific publications. For patents, trends, and geographic distribution are analyzed, while for scientific publications, a comprehensive overview of subtopics, subject areas, top journals of publication, distinctive trends, geographical distribution, affiliations, document types, and the central focus of previous studies are examined. From the results, the main questions on research diversity, dimensions, dominance, methodological approach, evolution, trends, and commercial relevance among others are discussed.

A novel radiative cooling and solar collection concept is presented, and the combination of these two technologies and its energy integration in residential and commercial buildings is evaluated. This innovative concept, herein named Radiative Collector and Emitter (RCE), allows for supplying both cooling and Domestic Hot Water (DHW) demands. First, the RCE concept is introduced by presenting its background, with special attention to the overlapping and switching between radiative cooling and solar thermal collection. Then the DHW and cooling demands for four building typologies, two residential and two commercial, are compared with the energy production of the RCE. The analysis is performed for representative cities of the world climates according to Köppen‐Geiger classification. The RCE concept showed suitability in some of the studied cities (San Francisco, Cape Town, Johannesburg, London, and Ottawa) with C (temperate) and D (continental) climates in residential and tertiary buildings. Suitable technology! A new concept, the Radiative Collector and Emitter (RCE), combining radiative cooling and solar collection is analyzed. The RCE concept showed suitability in some of the studied cities (San Francisco, Cape Town, Johannesburg, London, and Ottawa) with C (temperate) and D (continental) climates in residential and tertiary buildings, covering more than 25 % of the cooling demand and more than 75 % of the domestic hot water demand.

Public universities face the challenge of retrofitting the actual campus buildings into nearly zero-energy buildings (NZEB). In this study, a novel methodology for evaluating historical energy use and renewable energy production for all the buildings of a university, including hourly, daily and monthly data assessments is presented. This analysis is useful as a baseline for comparisons with future energy retrofits and enables determining the current gap between actual energy indicators at building and campus levels and the established limits for NZEB non-residential buildings in the European Union. The methodology is applied to a case study at the University of Lleida, a typical average-size university in Spain. Results show a wide variation in energy use among campus buildings, ranging between 50 and 470 kWh/m2year. Constant or slightly increasing energy use and decreasing trends in renewable energy generation are observed. The daily electricity profiles have shown similar patterns among buildings and substantial potential energy savings during unoccupied periods. In the NZEB analysis, the average non-renewable primary energy use is about 4 times higher than the maximum estimated Spanish threshold range of 45–55 kWh/m2year. Deep energy renovation strategies are, thus, needed for universities to meet EU NZEB targets.

Catalonia (Spain) has a significant potential of biogas production from agricultural activities and municipal waste. In addition, there are plenty of industrial cogeneration plants, but most of them use conventional fuels, such as natural gas, and conventional energy conversion devices, such as internal combustion engines. Molten carbonate fuel cells are ultraclean and highly efficient power generator devices capable of converting biogas into electricity and heat. Located in Lleida (Catalonia), Nufri is a fruit processing company with a long tradition on biogas production and cogeneration, with an installed capacity bigger than 45 MW. This study analyzes the economic viability of a fuel cell operating on biogas in Spain, on a real case basis (Nufri). Different fuel cell capacities are analyzed (from 300 kW to 1200 kW). A parametric study of different fuel cell prices ($/kW installed) is performed. Additional biogas cleanup requirements are taken into account. The results are based on the Spanish legislation, which establishes a special legal framework that grants favorable, technology-dependent feed-in premiums for renewable energy and cogeneration. Results show that the payback period ranges from 5 years to 8 years depending on the fuel cell capacity and installation price.

Catalonia (Spain) has a significant potential of biogas production from agricultural activities and municipal waste. In addition, there are plenty of industrial cogeneration plants, but most of them use conventional fuels, such as natural gas, and conventional energy conversion devices, such as internal combustion engines. Molten carbonate fuel cells are ultraclean and highly efficient power generator devices capable of converting biogas into electricity and heat. Located in Lleida (Catalonia), Nufri is a fruit processing company with a long tradition on biogas production and cogeneration, with an installed capacity bigger than 45 MW. This study analyzes the economic viability of a fuel cell operating on biogas in Spain, on a real case basis (Nufri). Different fuel cell capacities are analyzed (from 300 kW to 1200 kW). A parametric study of different fuel cell prices ($/kW installed) is performed. Additional biogas cleanup requirements are taken into account. The results are based on the Spanish legislation, which establishes a special legal framework that grants favorable, technology-dependent feed-in premiums for renewable energy and cogeneration. Results show that the payback period ranges from 5 years to 8 years depending on the fuel cell capacity and installation price.