Optimal allocation of the food, energy and water (FEW) resources is of emergent concern owing to depleting supply of the natural resources. Increasing demand for the FEW resources is attributable to growing population, migration, economic development, technological advancements and climate change. The FEW nexus (FEW-N) is an intricate system that requires robust quantitative decision-making tools to investigate the links between the various system components and sustainability. This study proposes a meta-model-based FEW-N system for addressing the issue of natural resource allocation for food and energy security. It incorporated an integrated model consisting of the Techno-Economic and Input/Output models in an Optimisation framework with maximum economic benefit as its objective function. The COINOR Branch and Cut (CBC) and CPLEX solvers in the Advanced Interactive Multidimensional Modelling System (AIMMs) were used to formulate and solve the optimisation problems. To validate the developed framework, the scenario analysis was performed on three cases in South Africa. First, it was found that using FEW resources for food production in dryland open fields, undercover greenhouses, and irrigated open fields was more profitable than for production of electrical energy from bioenergy, solar/wind-based hybrid renewable energy, and hydropower production systems. Second, the revenue of the sub-sector determined the percentage use of the FEW resources and the percentage contribution of technology options to food and energy security. Third, open fields, greenhouses, and irrigated open fields contributed significantly to food security. The holistic framework developed provided enhanced understanding of the FEW-N system. Resource security has significantly improved due to the ability of various technologies in each subsector to meet the food and energy demands of the specific population. Besides providing scientific support for national decisions regarding food, energy, and water policy, the proposed framework will also contribute to sustainable development at the subnational level.

Poverty, food insecurity and climate change are global issues facing humanity, threatening social, economic and environmental sustainability. Greenhouse cultivation provides a potential solution to these challenges. However, some greenhouses operate inefficiently and need to be optimized for more economical and cleaner crop production. In this paper, an economic model predictive control (EMPC) method for a greenhouse is proposed. The goal is to manage the energy-water‑carbon-food nexus for cleaner production and sustainable development. First, an optimization model that minimizes the greenhouse's operating costs, including costs associated with greenhouse heating/cooling, ventilation, irrigation, carbon dioxide (CO₂) supply and carbon emissions taking into account both the CO₂ equivalent (CO₂-eq) emissions caused by electrical energy consumption and the negative emissions caused by crop photosynthesis, is developed and solved. Then, a sensitivity analysis is carried out to study the impact of electricity price, supplied CO₂ price and social cost of carbon (SCC) on the optimization results. Finally, a model predictive control (MPC) controller is designed to track the optimal temperature, relative humidity, CO₂ concentration and incoming radiation power in presence of system disturbances. Simulation results show that the proposed approach increases the operating costs by R186 (R denotes the South African currency, Rand) but reduces the total cost by R827 and the carbon emissions by 1.16 tons when compared with a baseline method that minimizes operating costs only. The total cost is more sensitive to changes in SCC than that in electricity price and supplied CO₂ price. The MPC controller has good tracking performance under different levels of system disturbances. Greenhouse environmental factors are kept within specified ranges suitable for crop growth, which increases crop yields. This study can provide effective guidance for growers' decision-making to achieve sustainable development goals.

Water, energy and food (WEF) are three basic elements that safeguard human life and socioeconomic development. As the demand for water increases in food and energy production, water scarcity is more prominent globally. WEF Nexus plays an important role in evaluating and alleviating the contradiction between food and energy for water. Based on the water footprint of food and energy in China from 1997 to 2016, this paper used the “Structure-Conduct-Performance” analysis paradigm to evaluate the water competition mechanism. The newly constructed competition mechanism model includes type, conduct and performance. The results showed that the blue water footprint of energy increased from 3.25 Gm³ in 1997 to 12.54 Gm³ in 2016. The blue water footprint of food remained above 200 Gm³ for many years, and competition between food and energy production for water was intensifying. The gray water footprint of energy was increasing yearly, and food reached the maximum value of 181.01 Gm³ in 2014. Through model analysis, the South-to-North Water Diversion has not effectively alleviated water scarcity, and a few provinces were still classified in the water pressure-dominated area. The northern channel of West-to-East Power Transmission only transferred electric energy from water pressure-dominated area, causing the unsustainability coefficients of Inner Mongolia and Yunnan to increase from 0.09 and 0.03 in 1997 to 0.23 and 0.05 in 2016. This paper provides effective policy insights for global challenges facing WEF Nexus from the source, process and end of food and energy production.

In the present study, a well-defined set of chitosans, with different degrees of acetylation (DA) and degrees of polymerization (DP), were processed by solution electrospraying from a water-based solvent. The solution properties, in terms of surface tension, conductivity, viscosity, and pH, were characterized and related to the physico-chemical properties of the chitosans. It was observed that both DA and DP values of a given chitosan, in combination with biopolymer concentration, mainly determined solution viscosity. This was, in turn, the major driving factor that defined the electrosprayability of chitosan. In addition, the physico-chemical properties of chitosans highly influenced solution conductivity and results indicated that the chitosan solutions with low or low-to-medium values of conductivity were the most optimal for electrospraying. The results obtained here also demonstrate that a good process control can be achieved by adjusting the working conditions, i.e . applied voltage, flow-rate, and tip-to-collector distance. Finally, it was also shown that electrosprayability of chitosan with inadequate physico-chemical properties can be improved by solution mixing of very different kinds of this polysaccharide. The resultant electrosprayed submicron chitosan capsules can be applied for encapsulation of food additives and to develop bioactive coatings of interest in food packaging, where these particles alone or containing functional ingredients can be released from the package into the food to promote a health benefit.

The energy-water nexus is a concept widely established but rarely applied to product and, in particular, to food and beverage products, which have a great influence on greenhouse gases emissions. The proposed method considers the main nexus aspects in addition to other relevant aspects such as climate change, which is deeply linked with energy and water systems, and assessing process as well as product. In this framework, this study develops an integrated index (IWECN) that combines life cycle assessment (LCA) and linear programming (LP) to assess energetic, water and climate systems, enabling the identification of those products with minors energetic and water intensity and climate change effects and helping to the decision-making process and to the development of eco-innovation measures. In this case, the product assessed was one bottle (70 cl) of gin and two main hotspots were identified: the production of the glass bottle and the energy requirements of the distillation stage. Based on that, several eco-innovation strategies were proposed: the use of photovoltaic solar energy as energy source and the substitution of the glass bottle by a plastic one and by a tetra brick. The nexus results indicated that the use of solar photovoltaic energy and plastic as bottle material was the best alternative decreasing 58% the IWECN value of the production of one bottle of gin. The sensitivity analysis presented a strong preference for photovoltaic solar energy in comparison with electric power and for the reduction of the glass bottle weight or its substitution by a plastic bottle. The use of the IWECN index is extendable to any product with the aim of facilitating the decision-making process in the development of more sustainable products to introduce them in new green markets.