BERLIN -- Electric vehicles are a powerful weapon in the world's battle to beat global warming, yet their impact varies hugely from nation-to-nation and in some places they pollute more than gasoline models, data analysis shows.
In Europe, where sales are rising the fastest in the world, EVs in Poland and Kosovo actually generate more carbon emissions because grids are so coal-reliant, according to the data compiled by research consultancy Radiant Energy Group (REG).
Elsewhere around Europe, however, the picture is better, though the relative carbon savings depend on what supplies grids and the time of day vehicles are charged.
Best performers are nuclear and hydroelectric-powered Switzerland at 100 percent carbon savings vis-a-vis gasoline vehicles, Norway 98 percent, France 96 percent, Sweden 95 percent and Austria 93 percent, according to the study shared with Reuters.
Laggards are Cyprus at 4 percent, Serbia 15 percent, Estonia 35 percent and the Netherlands 37 percent.
An EV driver in Europe's biggest car manufacturer Germany, which relies on a mix of renewables and coal, makes a 55 percent greenhouse gas saving, the data also showed.
In countries like Germany or Spain with big investment in solar and wind, lack of renewable energy storage means the amount of carbon saved by driving an EV depends heavily on the time of day you recharge.
Charging in the afternoon - when sun and wind are more prevalent - saves 16-18 percent more carbon than at night when grids are more likely to be fueled by gas or coal.
The analysis, based on public data from Europe's transmission system operator transparency platform ENTSO-E and the European Environment Agency (EEA), came ahead of Wednesday's discussions on transport at the COP26 summit.
It showed how the auto industry's ability to reduce emissions depends on finding better ways to decarbonize electricity grids and store renewable energy - challenges many European countries have not yet overcome.
Lithium ion batteries are only able to store energy at full capacity for up to around four hours, meaning even countries sourcing significant amounts of solar and wind power during the day struggle to keep it on tap for nighttime charging.