A little-known, but comprehensive study of resource limits is by L. David Roper, Prof. Emeritus of Physics, Virginia Tech. His methodology is thorough. He projects reserves, rates of extraction, and dispersion of resources in the earth – and allows for recycling. Each recycle pass loses some material; it can’t recover 100%.
Conclusion: we will not literally run out of anything. Extracting any resource is rarely like pumping out a tank with a sharply defined bottom. Instead, mineral depletion sets up a long, slow squeeze. After extracting easy-to-get deposits, the rest take more energy to concentrate. That little-hyped phenomenon is a slowly declining return on energy. Without discovering new sources of easily obtained energy – and materials – the global return on energy will continue declining. Over a few decades or a century, we must drastically revise our usage of resources – and how we think of them.
The prospect of declining return on energy of fossil fuels (peak oil) has no end of criticssome well reasoned but usually deficient in looking at all the inputs required to obtain energy, and without recognizing many external costs to the environment. And promises of a great alternative continue unabated. Hydrino energy is one of the latest.
A large-scale new source of energy might be discovered and developed, but as of this writing, no miracle seems likely. Even if it does, we can’t continue as we are. With unlimited energy we can continue devastating our environment, falling prey to all our other limitations. Optimism and channeled thinking leads us to believe that if we just “fix” one problem, all the rest will go away.
Of all the other resources that are limited, fresh water is crucial. Related to it is the reclamation of used water (sewage). Most of our answers to water shortages require energy: Pump it further. Desalinate. Purify the sewage. More promising interventions require little or no energy: Xeriscape. Small-scale catchments for grey water. Rationing supplies of potable water. And pollute less water. If we did not pollute so much water, obtaining adequate potable water would become a smaller problem.