Simple enough question but lets say what is it that we definitely cant live without. Yes definitely the tier 1 requirements would be Water, Air, Food, Energy. We will go in detail over them and then move on to items we need but can be more efficient with. I personally don't believe that only way we can survive is by not using it at all. The conservationist have this fundamental idea that by not using something it simply last for ever. Yes it can work but not every one wants to live like that. I believe we have an answer for 99% of the problems already her, we just don't want to do it because it not practical in our lives yet.
