Manure and money: electrodes and green electricity extract raw materials from faeces

3 billion tons a year. This is the amount of animal waste products in the form of excrement produced by livestock worldwide.

Some of this can be put to excellent use in the form of liquid manure to fertilize fields and other farmland. However, due to the sheer quantities involved, this cycle is reaching its limits, if it has not already been overstretched long ago.

This problem can be read about here, for example. In addition to biogas production and the splitting of long-chain molecules by bacteria, other methods are needed to deal with the waste - apart from the obvious solution of producing less meat.

A technique recently presented by the University of Wisconsin-Madison should help here. Basically, it is an electrode, comparable to the electrodes used in battery technology, which is immersed in liquid manure.

The composition of potassium, nickel, hydrogen, carbon and iron (KNiHCFe or potassium nickel hexacyanferrate for short) draws electrons from the liquid and ensures that many long-chain compounds break down.

As a result, potassium and ammonia in particular accumulate at the electrode. In the second step, the electrode is immersed in clean water and separated from the raw materials using electricity, which can now be recovered very easily in high concentrations.

Of course, it has to be worthwhile

A positive side effect: the second process also produces hydrogen and hydrogen peroxide. These two basic materials for many chemical processes are also valuable. One kilogram of potassium alone is traded for several hundred dollars.

The researchers have even extrapolated that all of the products obtained in this way could generate a profit of almost $200,000 for a farm with one thousand cows.

An electricity price of just under $0.08 was assumed for this. This can realistically be achieved wherever solar plants and wind turbines generate more electricity than needed at certain times. In other words, in the countryside, where the fattening farms are located.

Last but not least, emissions from animal production could be reduced. If overall production could also be reduced somewhat, it could even be reduced considerably.