How do people justify Hyperloop as a particularly green option when my initial thought would be that it uses a similar amount of energy as a normal train - which we already have as a popular option? Or is the energy cost of maintaining the vacuum & associated processes far less than energy cost of air resistance for a normal train?

My presumption is that the vacuum matter is no trivial undertaking considering the proposals in this article for extremely long tubes all the way across Europe. Not trying to be snarky - I'm not that familiar with the details of Hyperloop and genuinely intrigued by how one would create so much vacuum!