Ooops. Giant sloth not a lemur.
Also: we WILL go to Brown's gas.
What we should have is the whole chain whereby we fuel the next reaction with the waste/by products of the first or of the chain reaction preceeding it. So you do 'borrow' energy but in an unusual form and while its seemingly a closed circuit of loop? It isn't.
Its not designed to keep you in or out. To enslave anything. Not even oxygen.