Monday, February 18, 2008

Phosphorus Shortage for Biofuels?

I read an article entitled "Peak Phosphorus" a while ago and it is referenced below. My attention was drawn back to it again by a more recent one called "Biofuels and the fertilizer problem", also referenced at the end of this posting, to the effect that there may be insufficient phosphate fertilizer to produce biofuels. Phosphorus is an essential element in all living things, from plants to you and me, along with nitrogen and potassium - known collectively as, P, N, K, in the form of micronutrients that drive growth. Global demand for phosphate rock is predicted to rise at 2.3% per year, but this is likely to increase in order to produce biomass for biofuel production.
If the transition is made to cellulosic ethanol as a fuel, because whole plants are consumed in the process, not merely the seeds etc., yet more phosphorus will be required and less of the plant (the "chaff") will be available to be returned as plant rubble after the harvest, which is a traditional and natural provider of K and P.

Now, the original Peak Phosphorus article is very interesting, if a bit doom and gloom, but only because it attests to yet another declining resource, namely phosphate rock. Similarly to the well known Hubbert Peak analysis which predicts that individual oil wells or indeed the global production of oil reaches a maximum, beyond which it declines relentlessly, a similar function can be fitted to world phosphate production. The method can be adapted in terms of the Hubbert Linearization, which I described recently (in the posting "Coal Dearth Era"), and involves plotting the annual production (P) divided by total production to date (Q), i.e. the ratio, (P/Q), against total (cumulative) production to date (Q), yielding an intercept on the x-axis which corresponds to the ultimate recoverable reserve.

The result indicates that the peak for phosphate production happened in the US in 1988 and for the world in 1989. The really telling aspect of the article is the inclusion of a plot of world oil production versus world population, for which the two quantities can be seen to follow one another closely. The conclusion is that we literally eat oil, since it underpins almost all agriculture, certainly in the developed nations, but also N and P, as required by the Green Revolution, which has preserved us from a Malthusian die-off scenario - so far, at least. Population has only grown as it has because of cheap phosphate deposits and cheap energy to produce the mineral and to get it onto farms around the world.

In contrast to fossil fuels, say, phosphorus can be recycled, but if phosphorus is wasted, there is no substitute for it. The evidence is that the world is using up its relatively limited supplies of phosphates in concentrated form. In Asia, agriculture has been enabled through returning animal and human manure to the soil, for example in the form of sewage sludge, and it is suggested that by the use of composting toilets, urine diversion, more efficient ways of using fertilizer and more efficient technology, the potential problem of phosphorus depletion might be circumvented. It all seems to add up to the same thing, that we will need to use less and more efficiently, whether that be fossil resources, or food products, including our own human waste. We are all bound on this planet and depend mutually on the various provisions of her. There are now so many of us that we will be unable to maintain current profligacy. In the form of localised communities as the global village will devolve into by the inevitable reduction in transportation, such strategies would seem sensible to food production at the local level. "Small is beautiful" as Schumacher wrote those many years ago, emphasising a system of "economics as if people mattered".

Related Reading.
[1] "Biofuels and the fertilizer problem", By Tom Philpot, Energy Bulletin, February 14th, 2008.
[2] "Peak phosphorus", By Patrick Dery and Bart Anderson, Energy Bulletin, August 13th, 2007.


Anonymous said...

I was discussing your "peak..." articles today with a friend, who had read that the gases, methane, ethane etc, were being continually produced by the action (unspecified)of the "Magna and the Earth's crust". I had never heard of any such phenomenom before and wondered if you could enlighten me.
Peter Melia

Professor Chris Rhodes said...

Hi Peter.

There is a book entitled "The Deep Hot Biosphere" written by (the late) Thomas Gold which proposes that methane and other hydrocarbons, including oil (and coal) are produced at some depth within the earth by bacterial action.

It is also true that methane among other gases (ethane, CO2, H2, H2O etc.)is emitted from volcanoes, suggesting a geochemical origin.

The Russian/Ukrainian "abiogenic" theory of petroleum is also along the lines that chemical action within the earth produces methane, and this may also be the source of petroleum.

There are certainly chemical processes that take place in the earth, but of course no one has been able to drill down far enough or extensively enough over the earth's surface to know for certain what is going on.

I can't find much in the way of detail about it, but it is said that the Russians are undertaking "deep-drilling" in various regions, including the Caspian coast, by which I mean down to 5 km or so in some places, in order to access "abiogenic" oil, formed at depth.

On the other hand, the theory is not supported by Western geologists, who think it was all formed from cooking plant and animal remains over millenia.

So, yes, these materials probably are produced by internal earth processes to some degree, which some people take comfort from (including Gold) saying that peak oil is nonsense.

It's a nice thought, but as I see it, whether we can keep the world running or not depends on how quickly oil and gas can be recovered: i.e. if it takes 100 years to "refill" the giant fields in the Middle East, that won't dig us out of the energy-hole quickly enough that we can keep going, given the decline in oil and gas fields that will almost certainly begin within a decade or so.

Hope this is helpful.


Francesco Aliprandi said...

I'm not sure we reached peak phosphorus.

In this post (sorry, italian only at the moment) I updated data with the most recent available from IFA and USGS, and found that 1989 peak was surpassed in 2005. Moreover, USGS economically recoverable reserves are estimated to be 18 Tg, much more than the 8 Tg suggested by the Hubbert linearization.

The recent increase in the price of fertilizers may suggest that production can no longer keep pace with demand, but just like for oil we will knew we had a peak only looking backward.

Nice blog, btw.