B. Domenech

A MILP model to design hybrid wind–photovoltaic isolated rural electrification projects in developing countries

Electrification systems based on the use of renewable energy sources are a suitable option for providing electricity to isolated communities autonomously. Wind and hybrid wind–photovoltaic (PV) systems are increasingly getting attention. To electrify scattered communities, designs that combine individual systems and microgrids have recently proven advantageous. In this paper we present a mathematical programming model to optimize the design of hybrid wind–PV systems that solves the location of the wind–PV generators and the design of the microgrids, taking into account the demand of the consumption points and the energy potential. The criterion is the minimization of the initial investment cost required to meet the demand. The proposed hybrid model is tested with realistic size instances and results show the instances are efficiently solved. Moreover, the model is applied to real case studies in Peru; obtained results verify that the hybrid model efficiently finds solutions that significantly reduce costs.

A MILP model for the teacher assignment problem considering teachers’ preferences

The Teacher Assignment Problem is part of the University Timetabling Problem and involves assigning teachers to courses, taking their preferences into consideration. This is a complex problem, usually solved by means of heuristic algorithms. In this paper a Mixed Integer Linear Programing model is developed to balance teachers’ teaching load (first optimization criterion), while maximizing teachers’ preferences for courses according to their category (second optimization criterion). The model is used to solve the teachers-courses assignment in the Department of Management at the School of Industrial Engineering of Barcelona, in the Universitat Politecnica de Catalunya. Results are discussed regarding the importance given to the optimization criteria. Moreover, to test the models performance a computational experiment is carried out using randomly generated instances based on real patterns. Results show that the model is proven to be suitable for many situations (number of teachers-courses and weight of the criteria), being useful for departments with similar requests.

Experiences of community wind electrification projects in Bolivia: evaluation and improvements for future projects

Currently, early in the XXI century, an estimated 2400 million people depend on traditional biomass for heating and cooking and 1500 million people lack access to electricity (IEA, 2009). Lack of electricity particularly affects rural areas of developing countries (Kanagawa and Nakata, 2008), exacerbating the urban-rural gap. In Bolivia, 35% of the population, more than 3.5 million people do not have access to electricity. Electrification systems based on renewable energy have proved being adequate to provide decentralized electricity to isolated rural communities around the world (Chaureya et al., 2004). These autonomous systems are often much cheaper than the interconnected grid extension and use local resources, avoiding external dependencies which, in turn, promotes long-term sustainability of projects. In particular, micro-wind systems are an alternative with great potential to generate power in rural areas (Lew, 2000), although their use has been limited to date. In South America, a significant institutional effort was made in Argentina to develop rural electrification projects using wind energy in the province of Chubut (Seitz, 2006). In Peru, there are some demonstrative projects of the use of wind power to electrify isolated communities, the first one in El Alumbre (Ferrer-Marti et al., 2010). In Bolivia, the governments policies on rural electrification are governed by the Rural Electrification Regulation, which states that the Department of Energy is responsible for promoting sustainable development, seeking expanded coverage of electricity services throughout the country. Therefore it has the responsibility to update and develop the rural energy strategy, including the Indicative Rural Electrification Plan to facilitate the work of agents in the development of rural electrification. The basic principles that are taken into account are: