Carbon Per Transistor (CPT): The Golden Formula for Green Computing Metrics

TL;DR

This paper introduces the Carbon Per Transistor (CPT) formula, a comprehensive metric to quantify the carbon footprint of semiconductor chips from manufacturing to end-of-life, highlighting manufacturing emissions as the dominant contributor.

Contribution

The paper presents a novel CPT formula that integrates emissions across the entire chip lifecycle, providing a scientifically rigorous benchmark for evaluating semiconductor sustainability.

Findings

Manufacturing emissions account for 60-125 kg CO2 per CPU.

High-transistor-count chips like Apple's M-series have larger carbon footprints.

Manufacturing impacts outweigh operational emissions over device lifespan.

Abstract

As computing power advances, the environmental cost of semiconductor manufacturing and operation has become a critical concern. However, current sustainability metrics fail to quantify carbon emissions at the transistor level, the fundamental building block of modern processors. This paper introduces a Carbon Per Transistor (CPT) formula -- a novel approach and green implementation metric to measuring the CO$_2$ footprint of semiconductor chips from fabrication to end-of-life. By integrating emissions from silicon crystal growth, wafer production, chip manufacturing, and operational power dissipation, the CPT formula provides a scientifically rigorous benchmark for evaluating the sustainability of computing hardware. Using real-world data from Intel Core i9-13900K, AMD Ryzen 9 7950X, and Apple M1/M2/M3 processors, we reveal a startling insight-manufacturing emissions dominate, contributing 60-125 kg CO$_2$ per CPU, far exceeding operational emissions over a typical device lifespan. Notably, Apple's high-transistor-count M-series chips, despite their energy efficiency, exhibit a significantly larger carbon footprint than traditional processors due to extensive fabrication impact. This research establishes a critical reference point for green computing initiatives, enabling industry leaders and researchers to make data-driven decisions in reducing semiconductor-related emissions and get correct estimates for the green factor of the information technology process. The proposed formula paves the way for carbon-aware chip design, regulatory standards, and future innovations in sustainable computing.