Comparative life cycle assessment of alternating and direct current electric loads: The case study of a power supply unit

Abstract

Distributed energy systems operating in direct current have potential benefits if compared with systems in alternating current, due to the reduction of energy conversions. This study performs an energy analysis of an office building to estimate the potential energy benefits of replacing alternating current loads with direct ones. The results indicate that modest but measurable improvements in energy performance can be obtained, evidenced by a 1.27 % reduction in total energy consumption and 4.50 % decrease in computer-related use, a 1.62 % reduction in grid imports, a 2.16 % decline in PV energy exports, thereby enhancing overall energy efficiency and self-sufficiency. Moreover, the study aims to quantify the life cycle impacts reduction for electric loads in direct current, through the analysis of a computer's power supply unit. The results show that the impacts for the manufacturing stage, considering 17 categories, is between 15 % and 45 %. For both configurations the use phase impacts are predominant compared to manufacturing except for water use. The applied approach can be replicated for other electric loads and buildings to support the idea that direct current outperforms their counterparts in terms of energy and environmental performance and that direct current microgrids can be more sustainable also in a life-cycle perspective.