(620f) Design of Residential Polygeneration Systems Applied to Isolated Communities

Water, energy and food are critical resources for meeting the social demands and socioeconomic development of communities and societies around the world. Nevertheless, there are communities that do not have access to energy and, consequently, there is a lack of access to water and food. Many rural communities or small towns still do not have access to these resources mainly due to their geographic location that makes the interconnection with the electrical grid difficult; moreover, the provision of water from the public network is a big problem. Distributed energy generation is a promising way to generate electricity in remote places by isolated systems due to the generation units are close to the consumers and the transmission energy losses are negligible. One of the schemes of Distributed Generation is polygeneration, wich can be defined as the simultaneous production of two or more energy services and products, seeking to take advantage of the maximum potential of the consumed resources. Even though, it is necessary to generate energy for the development of communities, it also represents an environmental problem caused by the use of fossil fuels. Because of this, in this project we propose to include the use of renewable energies that complement the polygeneration system as well as the implementation of waste-to-energy technologies that aim to recover energy in a form of heat, electricity or fuels from a waste source.

This work presents a mathematical programming model for the design of a residential polygeneration systems in an isolated community considering the water-energy-food nexus. The problem consists in determining the optimal and sustainable configuration to satisfy the energy, water and food demands of the inhabitants. To meet energy demands, the existence of different cogeneration units, renewable energies such as solar collectors, aerogenerators and solar panels were considered. Water demand was satisfied by rainwater collection systems and wells. Wastewater generated in the community was sent to blackwater and greywater treatment plants. The treated greywater was used in gardening, cattle and agriculture. Different types of crops and animal production were considered to satisfy the food demands of the inhabitants. The municipal solid wastes generated were separated in plastic, metal, paper, glass and non-recyclable, the latter were treated in process plants such as pelletization, incineration, gasification, pyrolysis and anaerobic digestion to obtain, pellets, steam and natural gas that can be used as an energy source.

The objective functions consist in maximizing the profit of the project that involves sales of crops, animals, pellets, biofuels and solid waste that can be reused and the total annual cost that is constituted by the fixed cost of the technologies or process and their operation cost. Additionally, other objective functions consist in minimizing the fresh water consumption and minimization of greenhouse gas emissions.

The proposed model is a Linear Programming problem and it was implemented in the software GAMS to solve a case study in the community of Cochoapa el Grande located in the state of Guerrero in Mexico, which is the municipality with the highest index of poverty and marginalization in the country, mainly due to its geographical location. The results show that there are economically, socially and environmentally attractive solutions with the implementation of the proposed approach.