This paper develops operational methods for minimization of energy consumption of manufacturing equipment. It is observed that there can be a significant amount of energy savings when non-bottleneck (i.e., underutilized) machines/equipment are turned off when they will be idle for a certain amount of time. Using this fact, several dispatching rules are proposed. A detailed performance analysis indicates that the proposed dispatching rules are effective in decreasing the energy consumption of especially underutilized manufacturing equipment. In addition, a multi-objective mathematical programming model is proposed to minimize the energy consumption and total completion time. Using this approach, a production manager will have a set of nondominated solutions (i.e., the set of efficient solutions) which he/she can use to determine the most efficient production sequence which will minimize the total energy consumption while optimizing the total completion time.

A great amount of energy is wasted in industry by machines that remain idle due to underutilization. A way to avoid wasting energy and thus reducing the carbon print of an industrial plant is to consider minimization of energy consumption objective while making scheduling decisions. In order to minimize energy consumption, the decision maker has to decide the timing and length of turn off /turn on operation (a setup) and also provide a sequence of jobs that minimizes the scheduling objective, assuming that all jobs are not available at the same time.In this paper, a framework to solve a multiobjective optimization problem that minimizes total energy consumption and total tardiness is proposed. Since total tardiness problem with release dates is an NP-hard problem, a new greedy randomized multiobjective adaptive search metaheuristic (GRASPTETT) is utilized to obtain an approximate pareto front (i.e., an approximate set of non-dominated solutions). Analytic Hierarchical Process is utilized to determine the "best" alternative among the solutions on the pareto front. The proposed framework is illustrated on a case study. It is shown that a wide variety of dispersed solutions can be obtained via the proposed framework, and as total tardiness decreases, total energy consumption increases.

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