How much energy can salt crystals store?

Answer

Hi David,

First of all, clarify that seawater and living beings usually do not contain salt*crystals*. I disregard any kidney stones, gout, and other ailments; Colleagues are welcome to supplement as I am going to approach the problem on a smaller scale. In water, salts will dissociate: the attraction between positive and negative ions dilutes (literally) so that these ions can move through the solution “independently” of each other. The crystal structure is lost in this process.

If we look at your example of a glass of rain water and a glass of sea water, then indeed ions will flow from the glass with the high concentration to the glass with the low concentration until the amount of salt in both glasses is equal. Unlike the electric eel, both the positive ions and the negative ions flow to the rainwater, so that no net charge shifts: so you cannot speak of an electric current here. This process does produce (thermal) energy, but given your reference to the electric eel I don’t think you are referring to this.

An electric eel can spark because it is able to separate positive and negative charges across a cell membrane. This creates a potential difference (electrical voltage). By releasing the built-up voltage in one go, an electric shock of about 600 V is created.

To return to your question: how much energy can we extract from saline solutions: as much (or less, because no process is perfect) energy as it took to separate the charges present. The sideral must therefore continuously invest energy to maintain this defense mechanism.

Regards

Geert Jan Graulus