Rest assured, all existing TBM's are already operated by electric motors. And they need an amount of power that very doubtfully can be delivered by batteries.

Rest assured, all existing TBM's are already operated by electric motors. And they need an amount of power that very doubtfully can be delivered by batteries. It is a bit of time that I don't deal with those smallish diameter TBM's, of 14 feet or so but to give you a comparison, a 22 feet one has usually a head (just the head) driven by some 6 x 300 or 350 kW electric motors. In the FAQ of the boring company: https://www.boringcompany.com/faq/ https://www.boringcompany.com/faq/ they mention diesel locomotives, but personally I have only seen electric (battery) locomotives used during TBM excavations. And the plan is to make their TBM's speedier by augmenting the power (to the head), besides optimizing cycles and what not, thus most probably the TBM itself will be powered "traditionally" by cable electricity.