Optimization techniques applied to the design of integrated rural energy centres

Abstract

A major part of the energy needs of rural India and many other developing countries is met by non-commercial sources of energy. Considerable amounts of human and animal energy are also being spent in an inefficient manner for carrying out various domestic and agricultural tasks. The manner in which these animate and inanimate sources of energy are being used is having an adverse impact on both the quality of life and environment in rural areas. Efforts to identify and correct this grave energy situation affecting vast rural populations in the developing countries have only been recently initiated. In this context, very few attempts have been made in the development of analytical procedures for planning and design of rural energy centres. In this thesis, a systematic attempt is made to develop optimization models for the design of rural energy centres in an integrated manner. The problem of design of rural energy centres is first formulated as a single-objective optimization problem aimed at using all available and accessible sources of energy in appropriate devices to fully meet the total energy requirements of a village in an optimal manner. Optimization models are developed for each of the three important objective functions chosen, viz. (1) minimization of cost, (2) minimization of use of non-local resources, and (3) maximization of system overall efficiency. Energy requirements of tasks constitute a set of equality constraints, and limits on availability of sources constitute a set of inequality constraints. Peak power requirements of tasks and peak power availabilities of sources are also considered. Some sources can be stored for use in subsequent intervals, and certain other sources result in spin-off benefits. These aspects are also captured in the models developed. Time dependency associated with season-wise variation in the number of tasks and their energy requirements, and that in the number and availability of sources, is also incorporated in these models. These time-dependent single-objective optimization models are suitably modified into scenario-based optimization models for easy implementation on an interval-to-interval basis. Since practical situations demand consideration of multiple goals or objectives, the problem is re-posed as a multiple-objective optimization problem, considering all the three objective functions together. Goal Programming approach and Fuzzy Linear Programming approach to solve this model are presented. Focusing on the village Ungra in the state of Karnataka, South India, several scenarios have been investigated in the context of use of both single- and multiple-objective optimization models developed. The results obtained have revealed several interesting energy-use options in the case of Ungra. In order to understand the impact of variation of certain key parameters on the emerging optimal energy options, an in-depth sensitivity analysis has also been carried out.