Spanish researchers have discovered a novel way of removing carbon from the atmosphere - urine.
As the team points, out, it's available across all human societies, and is produced in large quantities close to the pollution hubs of large cities. And, they say, their method not only captures CO2 but turns it into fertilizer.
"For every molecule of urea in urine, one mole (a chemical unit used to measure the quantity of a substance) of ammonium bicarbonate is produced along with one mole of ammonia, which could be used to absorb one mole of atmospheric CO2," says Manuel Jiménez Aguilar of the Institute of Agricultural and Fisheries Research and Training of the Regional Government of Andalusia.
After absorbing the CO2, another unit of ammonium bicarbonate, which has been used in China as a nitrogen fertilizer for 30 years, is produced.
To prevent the urine from decomposing, the team adds a small proportion of olive waste water as a preservative. The mixture, they say, can absorb several grams of CO2 per litre in a stable manner and over more than six months.
The fluid created can be inserted into domestic and industrial chimneys to increase its absorption capacity.
"In developing countries this nutrient recovery system could be implemented thanks to its environmental advantages," says Jiménez. "If urine and faeces are recycled there and then, as much as 20 litres of water per person per day could be saved and this would reduce waste water treatment costs."