Zero-Sum Game

Posted on 8 Aug 2013 by Ruari McCallion

Sust-it, the energy efficiency website, questions whether describing electric cars as “zero emissions vehicles” is accurate

Zero emissions - a fair claim?

The energy label on an electric car may state “Zero CO2 emissions” but energy efficiency website Sust-It suggests that the claim may not be the whole story. When the electricity required to charge the batteries and the associated CO2 emissions created in electricity generation are factored in, they say that the green benefits then become less clear.

According to Vehicle Certification Agency (VCA), the latest Renault Clio 4 dCi 90 ECO (diesel engine) has CO2 emissions of 83g/km. The electric Nissan Leaf requires 173W of electricity to travel a single kilometer. The CO2 emissions produced to generate that amount of mains electricity, using the National Energy Foundations formula, equates to 94g. This comparison makes the diesel Clio more CO2 efficient by 206kg of CO2 per year, based on an annual mileage of 12,000 miles.

Sust-It finds that an electric car is cheaper to run. Based on 12,000 miles/yr, the Nissan Leaf will cost £483 a year, while Clio owners will have to pay out nearly double – £895. Savings are mainly driven by the tax differentials between the energy sources, rather than CO2 efficiencies in use. The major claimed environmental benefit of electric cars is zero tailpipe emissions on the move, which would reduce pollution in towns and cities.

“The perception is electric vehicles are the greenest way to travel; this only appears to be true if you’re using renewable electricity to charge the vehicle,” said a spokesman from Sust-It, while acknowledging surprise at their findings. “The concept of zero emissions for electric cars needs to be corrected. A first step would be to clearly show the CO2 emissions produced in electricity generation, and then display this on the showroom energy labels and marketing material.”

Sust-it’s website shows the electricity demand of charging electric and plug-in hybrid vehicles, along with the CO2 emissions produced in generating the electricity. The energy consumption figures are based on Vehicle Certification Agency (VCA) testing data and average energy costs.