Chapter 7 - Decision-making in optimization and assessment of energy systems

Abstract

In energy engineering, there are many instances that a system must be selected among similar potential systems, or an optimal solution of a system must be chosen from a set of optimal solutions. In Chapter 6, in case of multi-objective optimization problems, it was discussed that instead of having an optimal solution of single-objective problems, there is a set of optimal solutions, namely Pareto optimal frontier, that contains many or infinite number of solutions. All solutions located on Pareto front are equivalent from the optimization point of view, and none of them dominate other solutions. In practical application, such as the case of multi-objective optimization of energy systems, it is impossible to deal with numerous solutions, and one optimal solution must be selected for the optimal condition of the energy system. On the other hand, there are cases in energy engineering that designers must choose one system among several alternatives. In such cases, decision-making tools must be used to select one system or one solution among potential systems or solutions. Several decision-making tools have been developed that select one system or solution among many based on different criteria or objective functions. Some methods consider equivalent weigh for all criteria or objective functions; however, there are other methods that use weight factors for different criteria. Therefore, this chapter is dedicated to introduce decision-making methods for the aforementioned purposes. Both methods that consider equivalent weigh for criteria and those methods that work based on different weights of criteria are discussed. Discussed methods can be encoded into a form of computer code; however, for small decision-making processes, in some methods, calculations can also be performed by hand-calculation. There is also software for decision-making that is introduced in this chapter.