Easy Peasy - tangential runways. Central terminal area surrounded by a circular taxiway. Parallel arrival/departure runways organised in pairs around the circle, at a tangent to it, with the 'end' of the arrival runway next to the terminal, diametrically opposite to the 'start' of the departure runway. Taxiing distances almost zero.
Of course, airports will have to be twice as big but hey, we're saving the planet, aren't we?