Biofuels and the phosphorus end-game

In a recent essay, engineer Robert Bullard argues that biofuels may drain phosphorus resources. Oil, gas and coal may be finite resources, but so is phosphate rock, from which the key plant nutrient phosphate is made as a fertilizer. Bullard claims these resources are becoming 'scarce' and that a global phosphate 'end-game' will soon unfold. We agree with the fact that phosphate is a finite resource, but not that it is becoming scarce.

Phosphate rock resources are finite, but there are vast deposits left, enough to last for centuries. Let's have a look at the consumption and at the recoverable resources. We use the statistics from the FAO's The Use of Phosphate Rock for Sustainable Agriculture, 2004.

• In 1999, total world production of phosphate rock was 145.5 million tons (most recent firm figure).
• From 1975 onwards, phosphate consumption in the form of direct applications in agriculture has steadily declined, from 5.6% of the nutrient base, to a mere 1.4% in 1998. The trend is downward and expected to reach a mere 1% within a few years. So the growth rates in consumption as a percentage of the nutrient basis of crops, is downwards.
• The total world rock phosphate reserve base is estimated to stand at between 37 billion and 112 billion tons. Of this amount, 2.2 to 7.8 billion tons are of high commercial value because their P2O5 concentration soluble in neutral ammonium citrate (NAC), is higher than 5.9%. At current consumption rates this easily recoverable resource is enough to last us between 15 and 54 years. Once the high concentration resource base is depleted, there is an amount of low-concentration phosphate rock left that will cover the same needs for between 127 and 386 years.
• In the past 100 years, phosphate has been discovered at a rate that exceeds the rate of consumption.
• Vast unexplored phosphate deposits can be found offshore. Deposits of this type occur along the southeast coast of the United States of America, on the Peru-Chile shelf, off the coast of Namibia, on the Chatham Rise off New Zealand, off the coast of Baja California, Mexico, and off the Congo River delta. None of these offshore deposits is being mined, and they will probably not be mined while ample reserves exist onshore.

These figures allow us to conclude that only the high-concentration phosphate rock reserves are limited, but four factors assure the continuity of supply: (1) phosphate application rates are continuously declining (2), vast recoverable reserves with low to medium concentrations have long been identified, (3) historically, new phosphate deposits have been discovered at a rate that exceeds consumption and (4) vast (moderate to high-concentration) resources exist off-shore. These resources are currently not exploited because there are ample onshore deposits.

We do want to present Bullard's case, because he is correct about the limited amount of easily recoverable high concentration resources, which may, in the medium term, influence prices. Bullard: Tom Friedman's recent op-ed piece, "Brazil's ethanol lesson: Barrels from bushels works," was uncharacteristically simplistic. The title should have included, at least, "for now." The use of agricultural resources for energy production does nothing more than buy a little time, much as the farmer who has a couple of bad years and jacks up his mortgage to cover acute losses by incurring an addition to his already burdensome long-term debt.

The ultimate folly in bioenergy sources as a significant solution to our energy needs for many years to come lies not so much in the resulting devastation of terrestrial and aquatic natural ecosystems or the urgent need to deal with global warming by going beyond "carbon neutral" to "carbon reduction," rather in the fact that civilization is not energy or water-limited, but is phosphorous-limited.

There are no substitutes for phosphorous in organisms, albeit, some need only very minute amounts. The vast majority of food produced for humanity depends on our agriculturists adding phosphorous (fertilizer) to the cultivated land:
ethanol :: biodiesel :: biomass :: bioenergy :: biofuels :: energy :: sustainability :: phosphate :: fertilizer ::

The bad news is this phosphorous is mined from rather accessible, but not very numerous, ore deposits throughout the world, a significant one of which is nearing depletion down Interstate 4 from Daytona Beach in Polk and Hillsborough counties. The really bad news is that, except for a rather small fraction of the applied phosphorous that ends up as recyclable in the residues and waste products associated with cultivated plants, most applied phosphorous is either locked up chemically by soil reactions or, as it is released over time, is leached by rainfall or irrigation to deep soil beyond the reach of plant roots.

What all this means is that, as we deplete the minable phosphorous, as we are surely doing for oil, gas and coal, but for which there is virtually endless alternative energy from the sun, increasingly and unrelenting, human effort will be directed toward growing whatever can be grown on whatever phosphorous can be had from wherever.

Conceivably, that human effort at phosphorous production will involve the use of energy in an amount far greater than any produced by the ethanol end-game. For the doomsdayers, the last wars on our planet, not so long after we are gone, will not be fought over energy sources or ideology, but for the control of phosphorous, unless, of course, we can re-engineer the DNA of virtually everything on the planet to not need phosphorous for life.

Bullard, R. Biofuels drain phosphorus supply, Community voices, Daytona Beach News Journal Online - Oct. 6, 2006.