The long tailpipe is an argument stating that usage of electric vehicles does not always result in fewer emissions (e.g. greenhouse gas emissions) compared to those from non-electric vehicles. While the argument acknowledges that plug-in electric vehicles operating in all-electric mode have no greenhouse gas emissions from the onboard source of power, it claims that these emissions are shifted from the vehicle tailpipe to the location of the electrical generation plants. From the point of view of a well-to-wheel assessment, the extent of the actual carbon footprint depends on the fuel and technology used for electricity generation, as well as the impact of additional electricity demand on the phase-out of fossil fuel power plants.
Description
Plug-in electric vehicles (PEVs) operating in all-electric mode do not emit greenhouse gases from the onboard source of power but emissions are shifted to the location of the generation plants. From the point of view of a well-to-wheel assessment, the extent of the actual carbon footprint depends on the fuel and technology used for electricity generation. From the perspective of a full life cycle analysis, the electricity used to recharge the batteries must be generated from renewable or clean sources such as wind, solar, hydroelectric, or nuclear power for PEVs to have almost none or zero well-to-wheel emissions. On the other hand, when PEVs are recharged from coal-fired plants, they usually produce slightly more greenhouse gas emissions than internal combustion engine vehicles and higher than hybrid electric vehicles.
Because plug-in electric vehicles do not produce emissions at the point of operation are often perceived as being environmentally friendlier than vehicles driven through internal combustion. Assessing the validity of that perception is difficult due to the greenhouse gases generated by the power plants that provide the electricity to charge the vehicles' batteries. For example, the New York Times reported that a Nissan Leaf driving in Los Angeles would have the same environmental impact as a gasoline-powered car with compared to the same trip in Denver would only have the equivalent of . The U.S. Department of Energy published a concise description of the problem: "Electric vehicles (EVs) themselves emit no greenhouse gases (GHGs), but substantial emissions can be produced 'upstream' at the electric power plant."
A recent study by the German IfW shows that the increased electricity demand, and the resulting delay in the shutdown of coal-fired power plants in Germany, causes electric vehicles to have 73% higher emissions than Diesel vehicles.
Carbon footprint in selected countries
A study published in the UK in April 2013 assessed the carbon footprint of plug-in electric vehicles in 20 countries. As a baseline the analysis established that manufacturing emissions account for 70 g CO2/km. The study found that in countries with coal-intensive generation, PEVs are no different from conventional petrol-powered vehicles. Among these countries are China, Indonesia, Australia, South Africa and India. A pure electric car in India generates emissions comparable to a petrol car. The country ranking was led by Paraguay, where all electricity is produced from hydropower, and Iceland, where electricity production relies on renewable power, mainly hydro and geothermal power. Resulting carbon emissions from an electric car in both countries are 70 g CO2/km, which is equivalent to a petrol car, and correspond to manufacturing emissions. Next in the ranking are other countries with similar low carbon electricity generation, including Sweden (mostly hydro and nuclear power ), Brazil (mainly hydropower) and France (predominantly nuclear power). Countries ranking in the middle include Japan, Germany, the UK and the United States.
The following table shows the emission intensity estimated in the study for each of the 20 countries, and the corresponding emissions equivalent in miles per US gallon of a petrol-powered car: