Electric vehicles produce zero local emissions. However emissions will be produced if the electricity used to power them is generated by fossil fuels such as brown or black coal. If the electricity is generated using 'clean' forms of energy such as solar, wind, geothermal etc., emissions are effectively eliminated.
The energy mix in countries around the world varies considerably. In Australia about 80% of electricity generation is from coal fired power stations with about 23% generated from brown coal (mainly in Victoria). The amounts of CO2e generated in the various states of Australia are outlined in the Dept. of Climate Change's (DCC) National Greenhouse Accounts (NGA) Factors.
The MEC Calculator (left) uses the NGA factors (full fuel cycle) as the basis of the calculations methodology (see MEC Factors). These factors are in line with international standards. As is demonstrated by the calculator, electric vehicles consuming 14kWh per 100kms produce less CO2e than petrol vehicles. Note: in Victoria where the electricity is mainly generated from emissions intensive brown coal, light petrol cars (5.6ltrs per 100kms) have a smaller CO2e footprint than electric vehicles.
As the mix of energy sources continues to expand into a cleaner fossil/renewables mix, the emissions from an electric fleet will continue to decline in comparison to an oil based equivalent. Other steps such as smart grid technology currently under trial in a number of states will open the possibilities for better energy management and further reductions in emissions.
Figures from the Dept. of Energy in the US reveal similar findings. The following has been sourced from Wikipedia.
According to the US Department of Energy, CO2 emissions for electricity generated from coal result in 0.93 kg of CO2 per kWh or roughly 0.14 kg(CO2)/km. CO2 emissions from electricity produced from all types of fuel using the mix of sources in the US as of 2008 results in 0.61 kg of CO2 per kWh or 0.095 kg(CO2)/km from an electric vehicle with a 0.155 kWh/km; 0.56 MJ/km) energy consumption (typical). Gasoline used in Internal Combustion Engine automobiles produces 2.34 kg(CO2)/L directly and an undetermined amount of CO2 in refining the crude oil, and transporting the gasoline to retail point of sale. With a US fleet average of 11.0 L/100 km (very similar average to the Australian fleet) in 2008, this would indicate a CO2 production of 0.258 kg/km driven. Electric powered automobiles, even using the most CO2 intensive coal produced electricity, produce half the emissions of gasoline powered automobiles.
The US Environmental Protection Agency has a Greenhouse Gas Equivalencies Calculator that will confirm the calculations referenced above. It was last updated in November 2009.
Some have argued that the change over to an electric fleet will cause a huge increase in emissions from power plants and require massive infrastructure change. As has already been referred to, the resultant decrease in oil consumption from an emissions perspective would contribute to a net reduction in CO2e emissions. In response to such claims in the UK a Department of Transport spokesman stated:
"Electric cars powered from today’s UK generating grid would save up to 40% of the CO2 emissions of a conventional petrol car over its full life cycle. This saving can improve as the grid moves to using more low carbon power sources."
With regards to infrastructure issues, results from studies around the world have concluded that the impact of electric vehicles on the grid will not be a constraint to their roll out. Power plants typically are under utilised at night when most electric vehicle charging would occur. A UK report for example released in May 2009 states that:
Assuming a 10 per cent market penetration of plug-in hybrid electric vehicles and pure electric vehicles in the UK, the study showed a
Neville Jackson from Ricardo in the UK stated in referencing the report said:
As power generation in Australia and other countries moves to a cleaner mix, emissions associated with electricity will continue to decline. Switching to an electric fleet just makes common sense - in the local vernacular, it's a no brainer!