Battery Cars cause higher life cycle emissions than gasoline-powered series hybrid cars

In a  recent finding submitted by Christoph Meinrenken of
Columbia University it is said that ;

Battery cars powered by grid electricity promise reduced life cycle
green house gas (GHG) emissions from the automotive sector. Such scenarios

usually point to the much higher emissions from conventional, internal

combus-tion engine cars. However, today's commercially available

series hybrid technology achieves the well known efficiency gains in

electric drive trains (regenerative breaking, lack of gearbox) even if

the electricity is generated onboard, from conventional fuels.

Here, They analyze life cycle GHG emissions for commercially

available, state-of the-art plug-in battery cars (e.g. Nissan Leaf)

and those of commercially available series hybrid cars

(e.g., GM Volt, at same size and performance). Crucially, they

find that series hybrid cars driven on (fossil) gasoline cause fewer

 emissions (126g CO2eq per km) than battery cars driven on current

US grid electricity (142g CO2eq per km). They attribute this novel

finding to the significant incremental emissions from plug-in battery

cars due to losses during grid transmission and battery dis-/charging,

and manufacturing larger batteries.