Not sure about this
"The aircraft uses electrical power from the batteries to run most internal systems and that, coupled with its lightweight composite body, gives fuel savings of up to 20 per cent."
If you have four enormous engines running, in flight, I don't understand how batteries can help you save fuel during flight, since it costs fuel to carry their weight and then there is the battery charge/discharge energy efficiency. On the ground, yes, but I can't imagine ground fuel savings being all that much compared to in-flight fuel costs.
Can someone who knows about this please comment?