A study by engineers based at the Norwegian University of Science and Technology has questioned some common assumptions about the environmental credentials of electric cars.

Published this week in the Journal of Industrial Ecology, the "comparative environmental life cycle assessment of conventional and electric vehicles" begins by stating that "it is important to address concerns of problem-shifting". By this, the authors mean that by solving one problem, do electric cars create another? And, if so, does this environmental harm then outweigh any advantages?

The study highlights in particular the "toxicity" of the electric car's manufacturing process compared to conventional petrol/diesel cars. It concludes that the "global warming potential" of the process used to make electric cars is twice that of conventional cars.

The study also says - as has been noted many times before - that electric cars do not make sense if the electricity they consume is produced predominately by coal-fired power stations. "It is counterproductive to promote [electric vehicles] EVs in regions where electricity is produced from oil, coal, and lignite combustion," it concludes.

So, should this new study make us reassess the environmental credentials of electric cars? Or does the analysis and data help us, as the authors insist, improve the environmental performance of electric cars? As they say:

Although EVs are an important technological breakthrough with substantial potential environmental benefits, these cannot be harnessed everywhere and in every condition.

Please leave your thoughts below. If you are quoting figures or other studies, please provide a link through to the original source. I will also be inviting various interested parties to join the debate, too. And later on today, I will return with my own verdict.

This article originally appeared on guardian.co.uk