Let me first say that I realize the importance of stopping taxi fuel waste and pollution. A vital issue.
Also, I should say that I feel like a little old engineer in a flat-hat, shaking his head as he smokes his Woodbine. " It'll never work. "
No knowledge on the subject, just an engineer's gut feeling that the numbers just don't come together.
Decades of sitting in aircraft with a huge tug belting out black smoke to get us rolling. Fear for me nose-gear as the load threatens to buckle something expensive. Relief, as we start to roll, turning to that tight gut again as the whole lot clankels to a stop. Horrible forces on that NG, all to be replaced by a very few square inches of rubber? Mmmm...I've been wrong before. Takes flat'at off to scratch head.