by Rebecca Walker — May 2, 2011—TerraPass, a leading provider of carbon offsets, has released an update to its carbon footprint calculator, an online tool that helps individuals calculate their greenhouse gas emissions from driving, flying, and home energy usage. For the first time, the calculator now makes it possible to estimate greenhouse gas emissions from driving all-electric vehicles, says the company.
Though electric vehicles do not emit greenhouse gases directly, emissions arise from generating the electricity required to charge the cars’ batteries. Following the lead of the U.S. Environmental Protection Agency (EPA) the TerraPass calculator uses the “miles per gallon-equivalent” figure shown on vehicle sales stickers as an input to its calculations. Since electric cars don’t use gasoline, a “gallon-equivalent” is pegged at 33.7 kilowatt-hours, the quantity of stored electrical energy equivalent to the energy stored in one gallon of gasoline. For example, the EPA rates the all-electric Nissan Leaf at 99 miles per gallon-equivalent.
The all-electric vehicle calculations are available through the Alternative Fuel option on the main calculator page. This option also allows users to calculate the footprint of vehicles powered by biodiesel, compressed natural gas, and ethanol. In all cases, the user enters the miles per gallon (or gallon-equivalent) from their own experience or from the US EPA, as well as the number of miles they drive each year.
The calculator update also provides emissions estimates for all 2011-model cars on sale nationwide, making the TerraPass calculator the most comprehensive US vehicle calculator available. Though many calculators use EPA data, the EPA’s public dataset contained substantial errors and omissions this year.
Launched in 2004, TerraPass works with developers of greenhouse gas reduction projects to bring to market renewable energy and independently-verified carbon offsets. For more information, see the Web site.
