Analysis of energy use and carbon emissions from automobile manufacturing

Abstract

In this thesis, we study the energy use and emissions arising from automobile manufacturing. The automobile manufacturing sector is the 11th largest industrial sector globally in terms of energy use and emissions. The IPCC has set targets for reduction in emissions so that the average concentration of carbon dioxide in the atmosphere does not exceed dangerous levels. The materials production sectors have achieved significant reduction in energy use in the last few decades. Progress in the production and assembly of components has been harder to prove. Base load energy use continues to be a high fraction of energy use at manufacturing facilities. We study the energy use and emissions reported by automobile companies in voluntary disclosures to the Carbon Disclosure Project (CDP), and in their sustainability reports. A model of a typical global vehicle assembly plant is created by using data published in literature. We find a good fit of this data with the CDP data. A certain fraction of parts manufacturing is included inhouse. Then, a simple thermodynamic model of the factory is developed. This shows that air exchange causes a significant heating and cooling load at factories. Internal heat gains contribute to the cooling load. We then test various emissions reduction scenarios to see their effectiveness in reducing energy use or emissions. We find that most of the reduction in emissions intensity in the last few years is likely due to the economies of scale effect, in spite of significant emission reduction efforts by some companies. We predict a trend towards higher manufacturing energy consumption due to use of low weight, high energy intensity materials in order to reduce use phase emissions. At some point, manufacturing emissions might become as significant as use phase emissions. Even if emissions intensity of manufacturing can be decreased, increased demand means that absolute emissions will continue to grow. Right now, it does not appear that this sector is on a pathway towards meeting climate change goals.