So, it all depends on where you get your power. In the USA, most of the heaviest coal polluting utilities are in the east and mid-west states. Europe, China, India and South Africa all have their share of heavy emitters.
To see just how your area stacks up in terms of coal pollution in the world, check out CARMA. For a detailed US regional report on EV pollution, see InvestmentU.
Let's compare pollution from a typical gas powered car, and an EV powered from a clean coal plant. The averages are typical average values for the USA. They will be higher in some countries, and localities within the USA.
The chart shows the ICE car producing twice the CO2 at the EV, 1/2 the N0x, 1/15 the S0x, several hundred times more carbon monoxide, and a lot more hydrocarbons.
Again, these are very average values. Power plant emission can vary by 100% or more from plant to plant. However, the comparisons are clear. As new coal plants come on line, the coal numbers will drop considerably. This will in effect make the EV cleaner over time, even charging with coal fired power.
Electric cars are often considered clean in terms of emissions. While this is sometimes true, it is not that simple. The energy source used to provide power to the battery pack might not be so clean. This makes the electric car not so clean. Let's see how this works. This assumes utility production of power, which is not necessarily the cast. You can generate your own power, we have done it.
First of all, the chemical composition of coal promises loads of pollutants when burned.
Two kinds of coal and their chemical formulas - Lots of carbon means lots of CO2
Coal utilities not all so clean
Electric power is mostly provided by local or regional scale utility companies.
The dirtiest of these companies burn only coal to generate power. The next
burn a mix of coal, natural gas, and biomass. Power plant emissions vary a lot.
More utilities are adding wind, hydro, and solar panel energy to the mix. New coal plants use sophisticated control loops and are much cleaner than older plants. Emissions are considerably reduced, except for CO2. The generalized chart below shows a few specific reductions for illustration.
There are many more.
General comparison of coal fired power plants and reduced emissions.
Emissions are in Lbs per kWh of power generated. Note the absence of CO2
New Coal Plant - Pleasant Prairie Power Plant
Average C02 emissions for power sources
The bottom line
There is no simple answer to just how much cleaner electric cars are than combustion powered cars. You can not at this time accurately generalize that electric cars are dirtier than ICE cars. If you take the time and effort to research exactly where your power is coming from, you can then state how much cleaner your EV is over your ICE rig. If you generate your own solar or wind power, you can claim clean air transport now. As time goes on, the power generation industry will likely be regulated toward cleaner power production.
In the USA it appears that the hybrid EV
may be the cleanest running car in many states. The states where the battery EV is cleanest is in those where renewable hydro electricity rules.
Clean coal is a term for a number of technologies for reducing coal fired power plant pollution. Many of these methods have been in use for years. They have been successful, though expensive, as shown on the Pleasant Prairie example above. As for carbon dioxide emissions, that is another story. The Pleasant Prairie plant reports a 15% CO2 reduction.
CO2 reduction is difficult in a practical sense, and is the main focus of clean coal technology research today. CCS or Carbon Capture and Storage or Sequestration methods are under study today.
Charts showing average US electricity sources, and average annual emissions per type of vehicle. Courtesy US DOE Alternative Fuels.
The EPA has compiled a database US greenhouse emitter. It happens that coal power plants spewed out some 72 percent of reported emissions for the year 2010. Oil refiniries were the next biggest emitter at around 6% of total emissions.
Geographically, just 15 states host 20 of the top coal fired polluters. The top states of the 15 are: Texas, Pennsylvania, Florida, Ohio, and Indiana.