Gary’s Q&A

Listener question & Gary’s response · Transcript passage

Jesus Chan asks Gary, good morning from Laredo, Texas. If humans have been around for approximately 190,000 years and we live on a planet covered by over 70% water, why haven’t we been able to find an efficient method of desalination for seawater?

For starters, the fact that humans have been around in some form for hundreds of thousands of years doesn’t really explain why something hasn’t been discovered.

In reality, we are only 1 to 3 centuries into the scientific revolution, depending on how you define it, and maybe a bit over 100 years from having a detailed understanding of the structure of the atom.

That being said, the problem of desalination is trickier than it seems. Ions of sodium and chlorine float around in water at the atomic level. Removing the sodium and chlorine atoms from water is difficult, given their size.

One option is to boil the water, which takes energy. You can increase the temperature of the water, reduce the pressure surrounding the water, or both. Regardless of how you do it, it requires an input of energy. Assuming you have enough energy, desalination is very easy.

The other option is to use some sort of filter. If you had a filter that could filter out the ions, you still have a problem. If ions can’t pass through the filter, they pile up on the other side, making it difficult for the filter to work. Filters can also wear out and get clogged up over time and require replacing.

Absent any sort of miracle technology, which could come in the form of a membrane, desalinization will require a great deal of energy or expensive filters.