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  • Writer's pictureHydroPhos Team

Phosphorus: A Nonrenewable Resource

Phosphorus is a chemical element on the periodic table that is vital to all life - plants, animals, and bacteria. Within our bodies, it serves as a mineral that is a constituent of processes of DNA, RNA, ATP, ADP. Furthermore, phosphorus is a limiting factor in plant growth, meaning that vegetation can struggle to survive and reproduce in the absence of this element. Phosphorus is also a nutrient for living plant cells, as it is involved in several key plant functions, including energy transfer, photosynthesis, transformation of sugars and starches, nutrient movement within the plant, and transfer of genetic characteristics from one generation to the next. Therefore, as phosphorus is an irreplaceable input used for food production on our planet, the need for a consistent and stable supply of the element is crucial for our growing global society.


Historical evidence shows that the elemental form of phosphorus was first identified and discovered around 1669 by a German alchemist named Hennig Brandt. However, farmers (while not aware of the high concentration of phosphorus present) have been applying guano (bird excrement) to fields for hundreds of years to stimulate greater agricultural yields.


Phosphorus itself is not necessarily rare, but it exists predominantly in nearby insoluble forms, such as apatite and other metal complexes. The process of obtaining geographically concentrated forms of phosphorus is through mining phosphate rock, but the process of naturally forming phosphate rock is incredibly lengthy, taking 10-15 million years to form from seabed to soil via tectonic uplift and weathering. A valid question that then arises is: how much accessible phosphorus do we have left on Earth?

 

The total amount of mineable phosphorus reserves can be a rather controversial subject and one where the literature produces varying ranges. A value between 6,500 - 59,000 teragrams (1 teragram = 1.102e+6 US tons) of mineable phosphorus has been made known, with the Institute of Ecology claiming reserves to be 19,800 teragrams while the British Sulphur Corporation estimates 6,500 teragrams. Peak phosphorus (the maximum production of phosphorus before production declines due to the nonrenewability of the resource) is expected to take place as early as 2033 (see Figure 1).

 

While there is some uncertainty about how much phosphorus reserves are left in a given timeline, there is a general consensus that the quality of remaining phosphate rock is declining. In mined phosphate rock, there can be many other elements, chemicals, and particles located within the ore in addition to phosphorus. Unfortunately, the concentration of unwanted clay particles and heavy metals such as cadmium are increasing in mined phosphate rock, while the concentration of phosphorus is decreasing. These unwanted additions can create harmful environmental effects and eliminating them from the phosphate rock takes capital and energy intensive removal methods. Additionally, remaining phosphate reserves are becoming more difficult to physically access , and mining under sea beds in the ocean has already begun. Extracting phosphorus is now becoming dirty, costly, and inefficient. The conversion of phosphorus to synthetic fertilizers adds even more costs, transportation, and energy consumption as well.

 

It was not until after WWII that the use of mineral phosphorus sources grew exponentially (see Figure 2). Prior to the mid 20th century, phosphate rock reserves were relatively unexplored and thus inexpensive and abundant, however phosphate rock soon became an industry favorite over organic sources of fertilizer like guano and cow manure. As the Green Revolution took off in the mid 1950’s, mined phosphate rock demand soared alongside nitrogenous fertilizers, and fertilizer use sextupled between 1950 and 2000.

Unlike the natural long term biochemical cycle that recycles phosphorus back to the soil via dead plant matter (see Figure 3), industrial agriculture requires continual applications of phosphorus-rich fertilizers to soils that support repeated harvests where crops rarely become dead plant matter. The natural cycle is therefore broken and natural phosphorus soil replenishment is limited. Phosphorus molecules now avoid the closed loop system and take a linear path from mines to oceans (through agricultural runoff supported by moving waterways) at rates far greater than natural biogeochemical cycles that take millions of years to complete. 


The depletion of our phosphorus sources  poses a huge challenge to our agricultural, environmental, and economic systems. HydroPhos Solutions is actively working in the nutrient recovery space to supply and scale a consistent source of high quality phosphorus. As prominent science fiction writer and chemist Isaac Asimov stated, life can multiply until all the phosphorus has gone and then there is an inexorable halt which nothing can prevent.The need for a solution to fix the growing phosphorus challenge has never been more critical than now.


Figure 1: Peak Phosphorus Curve


Figure 2: Phosphate Rock Usage in the US


Figure 3: The Phosphorus Cycle



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