Juan Ignacio Montero

LCA and tomato production in mediterranean greenhouses

LCA is used to analyse and evaluate the environmental impact associated with the process of greenhouse cultivation of a tomato crop. Tomato production in kg is selected as a functional unit. Three different tomato production processes were compared: soil cultivation and open and closed hydroponic systems. Three different waste management scenarios were also analysed. The most significant negative environmental impacts were identified, enabling the application of the most suitable technology in order to mitigate their effects. The main negative impact of greenhouse tomato production derives from the waste of biomass and plastics, therefore suitable waste management is the best practicable environmental option to reduce this. The composting of biodegradable matter is the best way of managing this kind of waste. Improving the material composition of structures and auxiliary materials is also advised. Lastly, more rational management criteria for the supply of nutrients to the crop will have to be found.

Airflow Resistance of Greenhouse Ventilators with and without Insect Screens

Measurements of the discharge coefficients of ventilation openings with aspect ratios between 1 and 36, and with and without flaps attached by a hinge along one side, were made using a modified fan test facility. The discharge coefficient of an opening without a flap increased with aspect ratio. For openings with a flap and aspect ratios greater than 5, the discharge coefficient also increased with aspect ratio and the flow through the opening varied with the sine of the flap angle. As the aspect ratio decreased below five, flow through the triangular ends of ventilators with flaps became increasingly significant in comparison to the flow through the front rectangular face. The discharge coefficient of a ventilator with a flap was independent of whether the flow was into or out of the opening. New correlation equations were derived for discharge coefficients of ventilation openings, and these are compared with previously published data. The test facility was also used to determine the pressure differences required to create airflows through five insect-exclusion screens comprising well-defined, regular meshes. Pressure loss coefficients for the screens were obtained from the experimental values and correlated with functions of Reynolds number (based on fibre thickness or diameter) and screen porosity. The correlation equation was shown to compare well with the majority of values derived from five publications which reported data on 27 nets, meshes and screens. The correlation enables the discharge coefficient of a screened opening to be predicted from the aspect ratio and flap angle of the opening, the fibre thickness and porosity of the screen and air speed. The results show that for a given porosity, the discharge coefficient of a screened ventilator decreases as the fibre thickness decreases and also as the air speed decreases.

Environmental analysis of the logistics of agricultural products from roof top greenhouses in Mediterranean urban areas

BACKGROUND As urban populations increase so does the amount of food transported to cities worldwide, and innovative agro-urban systems are being developed to integrate agricultural production into buildings; for example, by using roof top greenhouses (RTGs). This paper aims to quantify and compare, through a life cycle assessment, the environmental impact of the current linear supply system with a RTG system by using a case study for the production of tomatoes. RESULTS The main results indicate that a change from the current linear system to the RTG system could result in a reduction, per kilogram of tomatoes (the functional unit), in the range of 44.4-75.5% for the different impact categories analysed, and savings of up to 73.5% in energy requirements. These savings are associated with re-utilisation of packaging systems (55.4-85.2%), minimisation of transport requirements (7.6-15.6%) and reduction of the loss of product during transportation and retail stages (7.3-37%). CONCLUSIONS The RTG may become a strategic factor in the design of low-carbon cities in Mediterranean areas. Short-term implementation in the city of Barcelona could result in savings of 66.1 tonnes of CO₂ eq. ha(-1) when considering the global warming potential, and of 71.03 t ha(-1) when considering that the transformation from woodland to agricultural land is avoided.

High decrease in nitrate leaching by lower N input without reducing greenhouse tomato yield

Nitrate pollution due to excessive N fertirrigation in greenhouse tomato production is a persisting environmental concern in the Mediterranean region. Driven by productivity rather than sustainability, growers continue to use very high N concentrations of more than 11 mM in greenhouse tomato production. A greenhouse study was conducted in Barcelona, Spain, over two growing seasons to analyze the effect of N concentrations from 5 mM to 11 mM (control) on tomato yield and physical quality. The relative environmental impact was calculated by using the life cycle assessment method (LCA). Our results show that N concentration in the nutrient solution can be reduced from 11 mM (control) to 7 mM under a daily mean drainage volume of 30%. This finding implies a 70% decrease in nitrate leaching without reducing tomato yield or quality. According to life cycle assessment, a reduction of 36% in N fertilizers leads to a 60% decrease in the potential impact of eutrophication, 50% decrease in the potential impact of climate change, and 45% decrease in the potential impact of photochemical oxidants.

Integrating Horticulture into Cities: A Guide for Assessing the Implementation Potential of Rooftop Greenhouses (RTGs) in Industrial and Logistics Parks

Abstract Recently, the application of rooftop greenhouses (RTGs) to integrate agriculture into cities has increased, although the area where they can be potentially implemented has not been quantified yet. Consequently, this paper aims to design a guide to evaluate the potential implementation of RTGs in industrial and logistics parks and to apply the guide to the case study of Zona Franca Park (Barcelona, Spain). Eight percent of the rooftops were identified as feasible for a short-term implementation of RTG, according to the defined technical, economic, legal, and agricultural criteria. Estimations indicated that the annual tomato production in this area could account for almost 2,000 tons, which is equivalent to the yearly tomato demand of 150,000 people. Besides, this production could substitute imported tomatoes, and avoiding their distribution would represent savings of 65.25 t of CO2 eq·m−2.

Improvement of Agricultural Life Cycle Assessment Studies through Spatial Differentiation and New Impact Categories: Case Study on Greenhouse Tomato Production

This paper presents the inclusion of new, relevant impact categories for agriculture life cycle assessments. We performed a specific case study with a focus on the applicability of spatially explicit characterization factors. The main goals were to provide a detailed evaluation of these new impact category methods, compare the results with commonly used methods (ReCiPe and USEtox) and demonstrate how these new methods can help improve environmental assessment in agriculture. As an overall conclusion, the newly developed impact categories helped fill the most important gaps related to land use, water consumption, pesticide toxicity, and nontoxic emissions linked to fertilizer use. We also found that including biodiversity damage due to land use and the effect of water consumption on wetlands represented a scientific advance toward more realistic environmental assessment of agricultural practices. Likewise, the dynamic crop model for assessing human toxicity from pesticide residue in food can lead to better practice in pesticide application. In further life cycle assessment (LCA) method developments, common end point units and normalization units should be agreed upon to make it possible to compare different impacts and methods. In addition, the application of site-specific characterization factors allowed us to be more accurate regarding inventory data and to identify precisely where background flows acquire high relevance.

Technical feasibility and carbon footprint of biochar co-production with tomato plant residue

World tomato production is in the increase, generating large amounts of organic agricultural waste, which are currently incinerated or composted, releasing CO2 into the atmosphere. Organic waste is not only produced from conventional but also urban agricultural practices due recently gained popularity. An alternative to current waste management practices and carbon sequestration opportunity is the production of biochar (thermally converted biomass) from tomato plant residues and use as a soil amendment. To address the real contribution of biochar for greenhouse gas mitigation, it is necessary to assess the whole life cycle from the production of the tomato biomass feedstock to the actual distribution and utilisation of the biochar produced in a regional context. This study is the first step to determine the technical and environmental potential of producing biochar from tomato plant (Solanum lycopersicum arawak variety) waste biomass and utilisation as a soil amendment. The study includes the characterisation of tomato plant residue as biochar feedstock (cellulose, hemicellulose, lignin and metal content); feedstock thermal stability; and the carbon footprint of biochar production under urban agriculture at pilot and small-scale plant, and conventional agriculture at large-scale plant. Tomato plant residue is a potentially suitable biochar feedstock under current European Certification based on its lignin content (19.7%) and low metal concentration. Biomass conversion yields of over 40%, 50% carbon stabilization and low pyrolysis temperature conditions (350-400°C) would be required for biochar production to sequester carbon under urban pilot scale conditions; while large-scale biochar production from conventional agricultural practices have not the potential to sequestrate carbon because its logistics, which could be improved. Therefore, the diversion of tomato biomass waste residue from incineration or composting to biochar production for use as a soil amendment would environmentally be beneficial, but only if high biochar yields could be produced.

Computational Fluid Dynamic Modeling to Improve the Design of the Spanish Parral Style Greenhouse

The Parral type of greenhouse is very common in Southern Spain and other areas of the Mediterranean Sea. It is a simple, low cost greenhouse structure. Ventilation is by small ridge openings that are covered with rolling flaps or operable vents. Some also had limited sidewall openings. These conditions results in major heat stress to the plants. Computational Fluid Dynamic (CFD) models of the greenhouses were developed. The models were two-dimensional, steady state using various viscosity models. The results for the airflow through the vent openings and the actual vent opening areas were used to calculate air exchange rates for wind speeds of 2, 3, 4, and 5 m/s. These results compare favorable to tracer gas measurements that were reported in earlier manuscripts. The model will be used to evaluate several design and management changes for this type of greenhouse.

Improving the Metabolism and Sustainability of Buildings and Cities Through Integrated Rooftop Greenhouses (i-RTG)

Food security in cities is an increasing concern due to the impact of climate change and the concentration of world population in cities. Urban agriculture (UA) aims at enhancing food production in urban areas, providing potential environmental advantages by reducing food transport, packaging and waste generation. Among UA alternatives, rooftop greenhouses (RTGs) are greenhouses built on top of urban roofs, in which mainly soil-less agriculture systems are used to produce food. When RTGs are integrated into the metabolism of their buildings, they exchange CO2, energy and water to improve their performance. This alternative is called integrated RTG (i-RTG). This chapter analyses the use of i-RTGs to improve buildings and cities’ metabolism and its particular application in the area of Barcelona. This analysis aims to define a new agricultural system from a technological and sustainability approach focusing on Mediterranean cities. Our research is based on the development and results of the Fertilecity project. A particular experimental analysis was conducted at ICTA’s i-RTG lab located near Barcelona. The main factors of interest are architectural and engineering requirements, urban integration, CO2 emissions management, energy consumption, food production, social integration and rainwater harvesting. This analysis has used different methods such as life cycle assessment (LCA), life cycle costing (LCC) and semi-quantitative assessments. Multiple integrated results were obtained both at the building and city scale. For example, we proved that the i-RTG and its flow exchanges with the building could help to save heating energy, waste generation, water consumption and CO2 emissions.

Technology for Rooftop Greenhouses

Rooftop greenhouses (RTGs) can generate significant advantages provided RTGs and buildings are connected in terms of energy, water and CO2 flows. Beyond the production of high-value crops, environmental benefits such as re-use of waste water, application of residual heat and absorption of carbon dioxide are derived from urban RTGs. Social benefits viz the creation of employment, social cohesion and so on are also important assets of RTGs. This chapter is focussed on RTGs technology. RTG share many common aspects with conventional greenhouses, but at the same time RTGs show attributes that should be discussed separately. Synergies such as using residual heat, rain water for irrigation, CO2 exchange, etc. are part of the common metabolism greenhouse-building. This chapter will concentrate on the available technology from conventional greenhouses which is more suitable for RTGs, particularly concerning greenhouse structure, covering materials, climate control and soilless cultivation systems.