To abstract and simplify the issue. Imagine there's a material A that there's only 100,000 of left. It takes only 1 energy to consume it and turn it into a si

To abstract and simplify the issue. Imagine there's a material A that there's only 100,000 of left. It takes only 1 energy to consume it and turn it into a single product. Also using it could cause -5 damage to the environment. You realize however that it is not sustainable, it's going to be done at some point in the future. You start to look for solutions. You find a new material that can replace the other material B, however it's not as good for making the products. It takes 5 energy to consume it and it takes 3 energy to make the product and then when recycled it takes another 3 energy.