• Ian Sutton

Nine Pounds of Gold

Updated: Nov 2, 2021

Nine Pounds of Gold. Energy Returned on Energy Invested. ERoEI.

Do you want to become super wealthy? Well, there’s plenty of gold in the ocean, just there for the taking.

Ocean waters do hold gold – nearly 20 million tons of it. However, if you were hoping make your fortune mining the sea, consider this: Gold in the ocean is so dilute that its concentration is on the order of parts per trillion. Each liter of seawater contains, on average, about 13 billionths of a gram of gold. There is also (undissolved) gold in/on the seafloor. The ocean, however, is deep, meaning that gold deposits are a mile or two under water. And once you reach the ocean floor, you’ll find that gold deposits are also encased in rock that must be mined through. Not easy. Currently, there really isn’t a cost-effective way to mine or extract gold from the ocean to make a profit. But, if we could extract all of that gold, there’s enough of it that each person on Earth could have nine pounds of the precious metal.

What this NOAA article is telling us is that it is not the absolute amount of a resource that matters — it is our ability to extract it economically. In the case of gold, it is highly unlikely that it will ever make sense to extract if from the sea. It is simply too dilute.

Energy Returned on Energy Invested. ERoEI.

So much for this “get rich quick” scheme.

With regard to gold, it really doesn’t matter how much the extraction process costs — the metal is not a fundamental necessity. But the same cannot be said of oil, natural gas and coal. As it becomes increasingly expensive to extract them from the ground there will be less energy (hence money) left over to fund other activities. Eventually there will come a point when it is no longer economic to extract them at all.

This point cannot be over-stressed. Whenever the topic of resource limitations comes up the initial reaction of most people is to consider the overall amount of that resource. “There is plenty of oil in the ground, so we will not run out of it for many, many years.” But, as the example to do with the nine-pound gold bars shows, the key question is not “How much is available?” but “How much can be extracted economically?

Further discussion of this important topic is provided in the article Energy Returned on Energy Invested (ERoEI).