Assessment of PHEV potential to reduce fuel use in Sweden using GPS data for car movements

Licentiate thesis, 2014

Roughly 30% of Sweden’s total greenhouse gas emissions originate from transport. These emissions need to be reduced to be able to reach the by The Swedish parliament adopted goal of a carbon neutral society in 2050. The plug-in hybrid electric vehicle (PHEV) allows for a major share of the fuel to be replaced by electricity from the grid and can thereby reduce greenhouse gas emissions, local pollutants, and energy insecurity. But the expected share of electric driving for a given battery size is dependent on the individual car’s movement. In this thesis we assess the potential to reduce fuel use in Swedish passenger car transport through an introduction of plug-in hybrid electric vehicles (PHEVs) by utilising a comprehensive data set on Swedish car movements logged by GPS. In paper I we analyse how individuality in movement patterns may affect the battery design and viability of PHEVs and enable electrification of vehicle kilometres in Sweden. We found that both optimal battery sizes and savings vary substantially between individual car movement patterns. As expected better economic conditions meant more cars with batteries, larger batteries and larger savings. Better charging options lead to a higher battery utilization and therefore to more cars viable as PHEVs and higher savings. We also found that the PHEV viability is dependent on the battery-capacity-independent investment cost, which if high can delay the introduction of PHEVs to the market. Due to good possibilities for recharging, regularity in movement pattern and in general higher yearly mileage, the commuters are on average reaching higher savings and their cars are in majority among the first to be viable as PHEVs. Therefore, commuters are likely to be the first drivers for whom the PHEV will be cost-effective. Paper II focuses on how different actors’ interest possibly could influence battery sizing and the resulting fleet TCO savings, electric drive fraction, and number of PHEVs. Our results suggest that different objectives among stakeholder could result in very different optimal battery sizes. Some interest can therefore be conflicting, while others can work together. The resulting fleet could for example reach a high share of PHEVs without reaching a high share of electric driving. The aim of paper III was to analyse the possibilities for regeneration in Swedish car driving. We found that the individual differences in energy use at the wheel and in braking power are large. Also the discrepancies in braking power profile between test cycles and real world driving were found to be considerable.