Introduction
The latest governmental policies aim to mitigate the carbon impact on the climate and accelerate the transition towards carbon neutrality by imposing stronger regulations on companies. The European Green Deal by the European Commission (2022) has set the guidelines for Europe to become the first carbon-neutral continent by 2050. Exact regulations on the EU level in the Corporate Sustainability Reporting Directive exist as a proposal to date, and companies should plan to apply them retrospectively for 2023 (European Commission 2021).
The semiconductor industry emits carbon dioxide from its large amounts of consumed energy. At the same time, machine sensors tracking consumption are rare, and the share of fixed and variable energy consumption is often unknown.
To detect the individual energy consumption types of a wafer fab, a process- and infrastructure-oriented discrete-event simulation model was developed that serves as a tool to determine the plant energy consumption within a fab.
This paper aims to develop an extension to the existing Operating Curve concept by investigating the effect of utilization on energy efficiency. It uses the results of discrete-event simulation on a fab level to verify the novel concept.
Simulation model
Modern simulation modeling, as a tool to create a less complex model of the real world, can use different techniques. Discrete-event simulation is one of them and operates at a low or medium-low abstraction level with the goal of simulating a production process, for instance.
Model entities were moving through a sequence of blocks where they were processed, delayed, seized, or released. Since the proposed model was based on a sequential flow network of several production processes, discrete-event simulation was chosen as an appropriate simulation technique. The simulation was created, verified, and validated using the simulation software AnyLogic 8.
Results
The semiconductor industry is facing pressure to reduce its extensive energy consumption, which requires transparency on the relationship between energy efficiency and original planning objectives.
The new concept of the Ecological Operating Curve added energy efficiency-related aspects to the existing and, so far, only economically motivated concept of the Operating Curve. It did not intend to function as a model on its own but was designed to provide an additional ecological view in synergy with the economic view. Simulation results of the constructed curve verified the derived formula for the novel Ecological Factor.
The concept extension revealed that, until a certain threshold of utilization, economic and ecological objectives mutually benefited each other.
Simulation results of Ecological and Economic Operating Curve for a given ɑₑ and ɑ