AIR POLLUTION AND CARBON EMISSIONS (electric car)

Electric cars contribute to cleaner air in cities because they produce no harmful pollution at the tailpipe from the onboard source of power, such as particulates (soot), volatile organic compounds, hydrocarbons, carbon monoxide, ozone, lead, and various oxides of nitrogen. The clean air benefit is usually local because, depending on the source of the electricity used to recharge the batteries, air pollutant emissions are shifted to the location of the generation plants. The amount of carbon dioxide emitted depends on the emission intensity of the power source used to charge the vehicle, the efficiency of the said vehicle and the energy wasted in the charging process.
For mains electricity the emission intensity varies significantly per country and within a particular country it will vary depending on demand, the availability of renewable sources and the efficiency of the fossil fuel-based generation used at a given time. Charging a vehicle using off-grid renewable energy yields very low carbon intensity (only that to produce and install the off-grid generation system e.g. domestic wind turbine).

2009_US_electricity_generation_by_wierdness. Created with excel and gimp.

An EV recharged from the existing US grid electricity emits about 115 grams of CO₂ per kilometer driven (6.5 oz(CO₂)/mi), whereas a conventional US-market gasoline powered car emits 250 g(CO₂)/km (14 oz(CO₂)/mi) (most from its tailpipe, some from the production and distribution of gasoline). The savings are questionable relative to hybrid or diesel cars (according to official British government testing, the most efficient European market cars are well below 115 grams of CO₂ per kilometer driven, although a study in Scotland gave 149.5gCO₂/km as the average for new cars in the UK), but would be more significant in countries with cleaner electric infrastructure. In a worst-case scenario where incremental electricity demand would be met exclusively with coal, a 2009 study conducted by the World Wide Fund for Nature and IZES found that a mid-size EV would emit roughly 200 g(CO₂)/km (11 oz(CO₂)/mi), compared with an average of 170 g(CO₂)/km (9.7 oz(CO₂)/mi) for a gasoline-powered compact car. This study concluded that introducing 1 million EV cars to Germany would, in the best-case scenario, only reduce CO₂ emissions by 0.1%, if nothing is done to upgrade the electricity infrastructure or manage demand.
In France, which has a clean energy grid, CO₂ emissions from electric car use would be about 12g per kilometer.
A study made in the UK in 2008 concluded that electric vehicles had the potential to cut down carbon dioxide and greenhouse gas emissions by at least 40%, even taking into account the emissions due to current electricity generation in the UK and emissions relating to the production and disposal of electric vehicles.
A 2011 report prepared by Ricardo found that hybrid electric vehicles, plug-in hybrids and all-electric cars generate more carbon emissions during their production than current conventional vehicles, but still have a lower overall carbon footprint over the full life cycle. The initial higher carbon footprint is due mainly to battery production. As an example, the study estimated that 43 percent of production emissions for a mid-size electric car are generated from the battery production.