Indirect and direct CO2 emissions of electric cars

This report compares the greenhouse gas emissions of conventional passenger cars and electric and semi-electric cars based on the current literature. Emissions are calculated over the entire vehicle lifecycle, making a transparent distinction between direct and indirect emissions. From this information, conclusions are drawn about the lifecycle CO2 emissions of electric and semi-electric vehicles relative to conventional  counterparts. To identify the parameters influencing emissions, a sensitivity analysis was performed.
 

Over the entire lifecycle, the CO2 emissions of a fully electric car are around 35% lower than those of a petrol-fuelled vehicle. The relatively higher emissions associated with production of an electric car and its battery are more than compensated during the use phase. These CO2 benefits will increase even more in the future as the share of renewables in the power supply continues to grow. 

CO2 emissions hybrids 

For plug-in hybrids, the relative share of battery-charged kilometres is of major influence on CO2 emissions. This share depends on various factors, including battery size, distance travelled and charging behaviour. The last of these is a particularly uncertain factor that can vary enormously from person to person. In this study three ‘charging scenarios’ were therefore run, varying from virtually no charging to twice-daily charging. 

The lifecycle assessment for hybrids shows that their CO2 emissions are again generally lower than those of conventional vehicles. With twice-daily charging, the CO2 benefits may be similar to those of fully electric vehicles: around 35%. With infrequent battery charging, though, the relatively high CO2 emissions in the production phase in fact lead to around 3% higher lifecycle emissions compared with a petrol car.