Forecasting the Impact of Growing Shares of Hybrid and Electric Vehicles on Future Emissions of Carbon Dioxide and Air Quality Pollutants

Electric vehicles such as hybrid, plug-in hybrid and battery electric vehicles are a low-pollution low-carbon alternative to conventional petrol and diesel vehicles. They currently only represent a fraction of the vehicle fleet, but demand and supply is rapidly accelerating. It is important to understand the changes in relative costs of electric vehicles, to inform scenarios of the future vehicle fleet mix and subsequent impacts on expected trends in emissions of carbon dioxide and air quality pollutants. This is of interest to policymakers worldwide who are under pressure to cut carbon emissions and improve urban air quality. Barriers to adoption of hybrid and electric vehicles still exist including the high initial cost. Total Cost of Ownership considers all vehicle costs to ascertain whether the cheaper running costs of electric vehicles can offset the higher initial cost. By modelling hybrid vehicle ownership costs from 2000 to 2015 in different geographic vehicle markets a link between cost and adoption is proven. This research found that ownership costs of hybrid and electric vehicles are falling compared to conventional vehicles, with costs already cheaper in the UK, USA and Japan with the current subsidies available, and findings that by 2030, subsidies could be phased out. This study uses three future fleet scenarios resulting from an extended generalized bass model. This model includes a fleet turnover unit with an age based scrappage curve to create scenarios of hybrid and electric vehicle uptake, which also includes the on-road fleet share of petrol and diesel vehicles by Euro standard. These scenarios characterize three different futures: Business as Usual, Battery Bonanza (where the current 2040 target of 100% hybrid and electric vehicle market share is met) and Diesel Persists, where battery price, fuel price and subsidy level vary depending upon market conditions. Hybrid and electric vehicles have lower operational CO2 and NOx emissions; however, most modelling studies to date are based on either single vehicle models or high-level estimates. This thesis assesses the impact the evolving fleet has on trends in tail-pipe emissions of CO2 and NOX from 2015 to 2040 over a typical UK urban road network. A coupled microscopic traffic and instantaneous emission-modelling framework that can properly account for the impact of traffic congestion was used to assess vehicle emissions over 24-hours of a typical day for the three future vehicle fleet scenarios. This thesis concludes that the adoption of hybrid and electric vehicles could reduce network level emissions of CO2 and NOx by up to 31.6% and 95% respectively by 2040, with greater effects during congested conditions.