To fully understand the true environmental impact of electric cars, one has to examine the ‘generation-to-wheel’ CO2 emission cycle. Generation-to-wheel emission is zero if the electricity used to charge the car originates only from renewable energy such as wind. In Ireland, the share of renewable energy in the electricity mix is targeted to be 40% by 2020. Thus electric cars provide an opportunity to reduce CO2 in the transport sector through the electricity system. The graphic below illustrates that even with the current mix of electricity electric cars emit less than half of the emissions of a conventional car i.e. 70 grams of CO2 for an electric car compared with 150 grams for a conventional car.
Generation to wheel emissions
More energy efficient
Conventional cars with internal combustion engines are extremely inefficient with 80% or more of the fuel energy lost through wasted heat. Decades of cheap oil has led to a disincentive to improve car engine efficiency. However oil price hikes in recent years combined with emissions policies have driven car manufacturers to focus on engine efficiencies and the revival of electric cars.
Electric cars provide a leap in energy efficiencies, even accounting for all stages of energy conversion, ecars are a clear winner, as illustrated below.
Cycle efficiency of ecars versus conventional cars