Identification of environmental impacts for the Vectus PRT system using LCA

Sammanfattning: Emissions from passenger transport causes impacts to the environment and human health. With increasing demand for urban transportation caused by population growth and urbanization new transport solutions are needed. Vectus Intelligent Transport develops a new transport solution with the Personal Rapid Transit (PRT) technology which provides individual, automated and on demand transportation. Vectus is currently building their first commercial system at the Suncheon wetlands in South Korea. One of the purposes with the Suncheon PRT system is to reduce the environmental impact on the unique eco-system of the wetlands. The PRT technology is considered a sustainable transport solution due to the fact that it is electrically powered. However, there has not until now been any detailed environmental analysis of a complete PRT system. In this thesis a life cycle assessment (LCA) for the Vectus PRT was performed to identify the parts of the system that contributed to the largest environmental impact and in which phase of the life cycle these impacts occurred, as well as the impact of some system changes. The Suncheon PRT system was used as a ground scenario. All processes needed to construct, operate and dismantle the system were included in the assessment and were used to build a material and energy flow model for the complete life cycle. For the overall system the track stood for the largest impact followed by the vehicles. These impacts occurred at different phases of the life cycle, the tracks during construction due to its large mass and vehicles during operation due to the energy demand. A track made of steel had a lower environmental impact compared to a concrete track due to its lighter structure. By using certified electricity mix the impact during the operation phase could be reduced by over 95 % for most of the impact categories studied. The choice of electricity mix during operation was the single most efficient way to affect the overall environmental impact of the system. Using power collection instead of batteries was the preferred alternative as the vehicle power system due to short lifetime for batteries and increase in number of vehicles to maintain passenger capacity due to charging time. By combining these configurations for the Suncheon PRT system the overall environmental impact could be lowered by about 50 %. According to the LCA a slight decrease in greenhouse gas emissions and increase of emissions of acidifying substances will occur compared to competing modes of transport, such as transportation with cars and buses, due to the construction of the Suncheon PRT. However, during operation minimal emissions will occur at the Suncheon wetlands thus fulfilling the purpose of the PRT. There is also a large potential to substantially lower the impact by choosing renewable power, an alternative not available for gasoline driven vehicles.