CO₂ enrichment in protected agriculture has been extensively studied as a strategy to enhance crop productivity, resource use efficiency, and climate resilience. This systematic review examines the scientific literature on CO₂ enrichment in greenhouses, vertical farms, and controlled environment agriculture (CEA) systems, with a focus on its impact on crop physiology, photosynthesis, agricultural yield, modeling and simulation techniques, injection technologies, and sustainability challenges. A comprehensive bibliometric and systematic search was conducted in the Scopus database using key terms related to CO₂ enrichment and sustainable protected agriculture, following the PRISMA methodology. From an initial set of 212 documents, 171 were selected after removing duplicates, inaccessible articles, and studies not directly relevant to this context. The findings indicate that CO₂ enrichment can significantly improve photosynthetic efficiency, water use efficiency, and crop productivity, although its impact varies depending on species, environmental conditions, and application strategies. Computational models, such as CFD and machine learning, have optimized CO₂ distribution in controlled environments, contributing to more precise and resource-efficient agricultural practices. However, environmental and economic concerns, particularly energy consumption, carbon footprint, and the sustainability of CO₂ sources, remain critical challenges. To ensure the sustainable adoption of CO₂ enrichment, it is essential to integrate renewable energy sources, carbon capture and reuse technologies, and advanced CO₂ injection systems. This review provides a holistic assessment of current knowledge, identifying opportunities and barriers for the development of climate-smart protected agriculture systems that align with global sustainability goals and contribute to food security and environmental stewardship.

This study addresses solar energy applications in protected agriculture, focusing on greenhouses and related technologies. A bibliometric and technical analysis is developed, covering research published between 1976 and 2024, to identify the main trends and challenges in the use of solar energy in controlled environments. The methodology was based on the PRISMA approach, using the Scopus database to retrieve relevant documents. From an initial total of 221 documents, 216 were selected after a filtering and debugging process, ensuring the relevance of the final set. In the analytical phase, the results showed a moderate growth of 3.68% in the annual publication rate, highlighting the impact of research on solar energy’s application to air conditioning and energy efficiency in greenhouses. Most of the studies reviewed feature hybrid systems that combine solar energy with other resources, and we highlight both advances in climate control through artificial intelligence and the implementation of photovoltaic and thermal technologies to improve the energy efficiency of agricultural systems. The results also underline the importance of tomato cultivation in the selected studies, reflecting its global economic impact. The conclusions highlight the need for the further integration of energy storage and desalination technologies, especially in arid regions with high solar irradiation, to ensure the sustainability of greenhouses. It is proposed that future research should address the wider implementation of hybrid systems and advanced climate control technologies, optimizing both the use of energy resources and the performance of crops under cover. In addition, it is recommended that international collaboration be strengthened to address technical and climatic challenges in protected agriculture and to expand the adoption of innovative solutions in different geographical contexts.

The dimensions of a passive greenhouse are one of the decisions made by producers or builders based on characteristics of the available land and the economic cost of building the structure per unit of covered area. In few cases, the design criteria are reviewed and the dimensions are established based on the type of crop and local climate conditions. One of the dimensions that is generally exposed to greater manipulation is the height above the gutter and the general height of the structure, since a greenhouse with a lower height has a lower economic cost. This has led some countries in the tropical region to build greenhouses that, due to their architectural characteristics, have inadequate microclimatic conditions for agricultural production. The objective of this study was to analyze the effect on air flows and thermal distribution generated by the increase of the height over gutter of a Colombian multi-tunnel greenhouse using a successfully two-dimensional computational fluid dynamics (CFD) model. The simulated numerical results showed that increasing the height of the greenhouse allows obtaining temperature reductions from 0.1 to 11.7 °C depending on the ventilation configuration used and the external wind speed. Likewise, it was identified that the combined side and roof ventilation configuration (RS) allows obtaining higher renovation indexes (RI) in values between 144 and 449% with respect to the side ventilation (S) and roof ventilation (R) configurations. Finally, the numerical results were successfully fitted within the surface regression models responses.

In Mexico, there are regions where the temperature drops below the minimum threshold for tomato cultivation (10 °C), requiring the implementation of auxiliary equipment to heat greenhouse air. The objective of this work was to estimate the energy consumption necessary to maintain climate requirements of a greenhouse located in Texcoco, State of Mexico, by using a model of energy balance implemented on Computational Fluid Dynamics (CFD) simulations. The temperature prediction relied on a numerical model based on CFD, proposing a benchmarking on the position and direction of the heater to estimate its effect on the thermal distribution. Results indicated that heater operation on January 2019, a power of 85.56 kW was needed to keep the greenhouse at 12 °C. Also, simulations indicated that electric heater used was not enough to get a homogeneous temperature inside the greenhouse. To achieve well-distributed thermal conditions, it was necessary to consider both the direction and position of heaters. Consequently, airflow direction became more important than height of the heater in order to homogenize the greenhouse area, given that the thermal gradient was reduced due to reverse heat flows.