ENERGY ANALYSIS OF THE USE PHASE OF CONVENTIONAL TIRES COMPARED TO GUAYULE NR TIRES

Abstract

ABSTRACT Guayule NR can be grown in the United States and offers a potentially more secure and sustainable alternative to the substantial Hevea NR that is imported from Southeast Asia. This paper presents the first rolling resistance and use-phase energy consumption estimates for guayule tires. The results of this study show that use-phase life cycle energy reductions can be achieved with NRs and that the rolling resistance coefficient (RRcnew) and reference service life (RSL) of the new tire are the critical parameters that pertain to energy and fuel efficiency. A tire's use phase accounts for approximately 86% of its life cycle energy consumption and thus is an important consideration in sustainability assessments. We calculated the use-phase energy consumption for two types of NR tires: a 100% guayule rubber tire and an experimental epoxidized NR tire. These two NR tires were compared against a conventional passenger tire made by Cooper Tire & Rubber Company. The ISO product category rules for passenger tires were used to determine energy consumption, while relevant data were measured from concept tires built in collaboration with Cooper Tire & Rubber Company. The results of this analysis showed that both experimental NR tires have improved use-phase energy consumption compared to conventional rubber tires. Although the epoxidized NR tire with low RRcnew consumes the least energy during the use phase, it is currently not being considered for commercial manufacture. The 100% guayule rubber tire shows a 6% reduction in energy consumption compared to the conventional rubber tire. Results of the sensitivity analysis showed a linear change in use-phase energy consumption with the relevant tire load and RRcnew and an inverse change with the average vehicle fuel efficiency and the RSL.