Dear Rosa,
It is unusual to send a message to a true hero, but it is so. False ecologists use sustainability without knowing what it is, since ignoring mathematical science you like so much (theoretical physics provisionally derailed).

We live in a world of abundance, and Mother Earth (Gaia) does not exist since the Earth by itself is not sustainable without the sun, which, besides light, sends us protons and electrons in huge quantities. Problem: we do not have yet the technologies to catch them and fabricate chemical substances through transmutations. However, we will do it in a few years if finally financing theoretical research toward true technological purposes. However, in a previous stage nuclear fusion is theoretically possible. I am finishing a paper on it and a bit more, published in a question of days or weeks (I do not give here references to previous ones).

So, keep your fingers crossed, we will soon live in a world, sustainable through objective theoretical science. This is my conviction, but you do not need to believe me today. So, continue the great work, I see that you are not alone.