It is permissible to put money in a riba-based bank without interest in cases of necessity in order to protect the money, if there is no Islamic bank. If there is an Islamic bank, then it is not permissible, because that is helping in sin, as the bank benefits from this money by using it in riba.
As for opening an account without putting money in it, there does not seem to be anything wrong with doing this, but it should be for a reason, and not just for no purpose, so as to avoid joining the people of falsehood in this matter.
And Allaah knows best.