Prospective Life Cycle Assessment of Epitaxial Graphene Production at Different Manufacturing Scales and Maturity

Rickard Arvidsson,Sverker Molander

doi:10.1111/jiec.12526

Abstract

SummaryEpitaxial growth is a potential production process for the new material graphene, where it is grown on silicon carbide (SiC) wafers at high temperatures. We provide first estimates of the life cycle cumulative energy demand, climate change, terrestrial acidification, and eco‐toxicity of this production. For this purpose, we applied prospective life cycle assessment (LCA) for three production scenarios (lab, pilot, and an industrial scenario), which reflect different production scales and technological maturity. The functional unit was one square centimeter of graphene. Results show that the three scenarios have similar impacts, which goes against previous studies that have suggested a decrease with larger production scale and technological maturity. The reason for this result is the dominance of electricity use in the SiC wafer production for all impacts (>99% in the worst case, >76% in the best case). Only when assuming thinner SiC wafers in the industrial scenario is there a reduction in impacts by around a factor of 10. A surface‐area–based comparison to the life cycle energy use of graphene produced by chemical vapor deposition showed that epitaxial graphene was considerably more energy intensive—approximately a factor of 1,000. We recommend producers of epitaxial graphene to investigate the feasibility of thinner SiC wafers and use electricity based on wind, solar, or hydropower. The main methodological recommendation from the study is to achieve a temporal robustness of LCA studies of emerging technologies, which includes the consideration of different background systems and differences in production scale and technological maturity.

Highlights

Graphene is a one-carbon-atom-thin material that has been described as a “wonder material” and as a “rising star on the horizon of materials science” (Geim 2009, 1530; Geim and Novoselov 2007, 183)
Between the pilot and industrial scenarios, impacts decrease by approximately 1 order of magnitude for the best case. This is partly in accord with the findings of Gavankar and colleagues (2014), which suggested a clear decrease in environmental impacts as the production scale and technological maturity increased
In this study, such reductions in impact did not take place between the lab and pilot scenarios, and not between pilot and industrial scenarios for the worst cases. The reason for this behavior is the dominance of one factor in the background system for the environmental impacts: the electricity required to produce the silicon carbide (SiC) wafer

Summary

Introduction

Graphene is a one-carbon-atom-thin material that has been described as a “wonder material” and as a “rising star on the horizon of materials science” (Geim 2009, 1530; Geim and Novoselov 2007, 183). Commercialization is yet limited, graphene has been suggested for use in many different areas, such as energy production and storage, including batteries and fuel cells (Brownson et al 2011); transparent electrodes in computer screens (Blake et al 2008); semiconductors in electronics (Van Noorden 2006); reinforcement in composite materials (Li and Zhong 2011); and environmental applications, such as water purification (Shen et al 2015). In order for graphene to be able to fulfill these promises, feasible and environmentally benign production processes are required. According to a patent analysis, there are currently three main production processes being developed toward large-scale production, namely, exfoliation, chemical vapor deposition (CVD), and epitaxial growth (Sivudu and Mahajan 2012). Air liquefied air Epitaxial graphene on silicon carbide (SiC) Lab Pilot Industrial Parameter Symbol BC WC

Methods

Results

Conclusion