This work presents a general mathematical programming model for satisfying water, energy and food needs in isolated and low-income communities involving different process integration approaches. The problem consists in determining the optimal and sustainable configuration to satisfy the energy, water and food demands. Also, the use of waste-to-energy technologies is proposed aiming to obtain valuated products from wastes to reduce the environmental impact. A multi-objective analysis is presented considering the consumption of fresh water, the greenhouse gas emissions and the cost of the integrated system as objective functions. As case study, the community with the lowest index of poverty and marginalization from the State of Guerrero in Mexico is presented. The results show that it is possible to satisfy the water, energy and food needs in isolated communities accounting for integrated processes.
Urbanization, increasing demands, and climate change are critical challenges to ensure water, energy, and food security. The water-energy-food nexus requires integrating tools to guide the allocation of resources and promote sustainability. This work presents a mathematical formulation for the optimal design and management of resources to enhance the water-energy-food nexus security. Resource security is measured through indicators related to the availability, access, and sufficiency of water, energy, and food. Furthermore, the problem was analyzed under different allocation schemes (social welfare, Rawlsian, Nash, and Rawlsian-Nash) to maximize the global resource security (including water, energy, and food) and obtain the optimal design of the system. Therefore, the water, energy, and food security indices are considered as the objectives of interest. To show the applicability of the model, a Mexican state evaluated by regions was selected as a case study. Results show that through this approach, the security of the water, energy, and food sectors could be increased 6%, 56%, and 26%, respectively, and 27% the security of the water-energy-food nexus using the social welfare scheme in the addressed case study. The proposed water-energy-food nexus framework can be applied to any region with the corresponding data.
The 2030 agenda for sustainable development sets goals to strengthen the economic, environmental, and social sectors of the world. Among the main objectives are to eradicate poverty in the world, guarantee food security and human well-being, as well as the sustainable production of resources. The most important challenges are in rural areas where it is difficult to access food, electricity, fuel, and sanitary services. To overcome resource limitations, the optimization of the water-energy-food nexus has been proposed to boost the economic development of disadvantaged rural communities, this has been addressed through the correct management of available resources to ensure that the inhabitants have access to basic social services and a healthy diet. In this work, a mathematical model is provided for the sustainable production via integration of water, energy, and food in disadvantage rural communities, determining the optimal mix of technologies to supply the utility demands and the variety of food to cover nutritional requirements. The model formulation is a Stochastic Mixed Integer Linear Program, and it considers the population change and the water and energy demand as uncertain parameters. A Mexican community was selected as case study demonstrating the applicability of the model. Results show that it is feasible to create a system that enables the community to be self-sufficient and provide a balanced diet for inhabitants using renewable technologies and considering waste treatment. Moreover, with the proposed integration, it is possible to reduce the poverty and marginalization index by 8% per year with proper profit management.
Security of the Water-Energy-Food Nexus has become a global concern, threatened by the rapid urbanization, unsustainable consumption of resources, population growth and climate change that exert pressure on resources to meet the socioeconomic demands. Water-Energy-Food Nexus is central for sustainable development and promoting efficient management of resources. Nevertheless, an efficient and sustainable Water-Energy-Food Nexus design requires the participation of multiple stakeholders in the decision-making process. This work presents a multi-objective optimization model for the design of a Water-Energy-Food system that involves the sustainable production of water, energy and food in areas that share economic activities through the industrial, agriculture and livestock sectors. Additionally, a multi-stakeholder assessment is presented to generate a set of solutions, where different priorities are given to the stakeholders. This approach allows quantifying the level of satisfaction of each of the stakeholders. Integration of resources is addressed according to economic and environmental objectives, such as the minimization of the cost of the system, water abstraction and greenhouse gas emissions. As case study, a region located in Mexico was selected based on its industrial activity and the challenges it currently faces in meeting resource demands due to low water availability. Results show that water reuse is crucial to improve the Water-Energy-Food Nexus sustainability. Also, it was found that the most affected sector for water scarcity is the agricultural sector. This model can be the basis for planning the Water-Energy-Food Nexus at regional level involving different stakeholders and for determining sustainable interactions between resources.
Currently, the security of basic resources such as water, energy, and food is regarded as essential for sustainable development. Nonetheless, population growth, economic development, and changing consumption patterns have caused stress on these resources. It is expected that, in the near future, in many parts of the world, it will be challenging to satisfy the demand of the population and the access to essential services. Assessing the availability and access to natural resources allows for making projections of future scenarios and, in this sense, developing policies to mitigate deficiencies in all these sectors. This work presents an approach to assess the progress on the water-energy-food nexus security through an index that involves availability, accessibility, and sustainability indicators of a region over a time period. The evaluation considering the Sustainable Development Goals allows for identifying vulnerabilities associated with the water-energy-food nexus. The state of Sonora in Mexico was selected as a case study because of its unequal distribution and accessibility of resources. Results show that water, energy, and food access is not at risk, but the importation of resources to meet the demand of the state makes the nexus unsustainable because the availability of resources is not enough to satisfy the services of the population. Nevertheless, projections for 2030 show slight improvements in the water-energy-food nexus security.
There remains considerable confusion in the scientific literature regarding the appropriate ways to evaluate how “good” a model is. The process of evaluating a model is without a doubt the most controversial step in the modeling process. This confusion arises more from semantics and differences in philosophical viewpoints than from debates over specific methodologies used. Regarding semantics, the term “validation” takes center stage, followed by terms such as “verification,” “confirmation,” “corroboration,” “credibility,” “qualification,” and “evaludation” (not a typo), which have been used in attempts to place “validation” within an appropriate context. Regarding philosophical viewpoints, some modelers have stated that “verification” and “validation” of numerical models of natural systems is impossible, but that their “confirmation” is possible. Oreskes et al. based their statements on an examination of the philosophical basis of these terms, thus their philosophical viewpoint is inextricably tied to their semantics. Other modelers have stated that “validation” simply means that a model is acceptable for its intended use because it meets specified performance requirements. Rykiel provided his statement while discussing the meaning of “validation” within the context of ecological simulation models. Still other modelers have coined the new term “evaludation” to avoid use of “validation” per se by combining it with the more neutral term “evaluation,” the intent being to keep the idea of “validation” visible while softening its connotation.
