Phosphorus can pollute the environment, but it’s also an element essential to human beings. Even if reserves of phosphorus might last longer than has sometimes been claimed, we should still rethink how we deal with this valuable commodity. By Felix Würsten
It wasn’t long ago that phosphorus was creating nasty headlines here in Switzerland. Following the Second World War, the phosphorus content of lakes and rivers increased continually, with alarming ecological consequences in some cases. Only towards the late 1980s did the degree of pollution decrease, thanks to the expansion of waste-water treatment, a ban on phosphates in detergents and a greener approach to agriculture.
Meanwhile, phosphorus has been causing a stir for other reasons. In recent years, the media have resorted to headlines such as: “The elixir of life is dwindling”, “The phosphorus crisis: the end of humanity?” This has been in response to a seemingly new idea put forward forcefully by various researchers, namely that phosphorus – an essential commodity to mankind – will run out in the foreseeable future. As in the case of crude oil, which has prompted lively debate about when global production will peak, these researchers have sketched a scenario for rock phosphate – the source of phosphate fertiliser – suggesting that production will already peak some twenty years from now.
In contrast to crude oil, which can be replaced by other energy sources, the situation with phosphorus would be far more critical if reserves were indeed about to be exhausted. Because phosphorus cannot be replaced. It is an essential element without which neither animals nor plants can exist. Apart from anything else, it also determines the efficiency of crop yields in the agricultural sector. If farmers cannot fertilise their fields with phosphate, food production in its present form would no longer be possible.
But just how serious is this supposedly impending crisis? “The situation isn’t as dramatic as it’s sometimes described”, explains Andrea Ulrich of ETH Zurich. She has examined the problem in her doctoral thesis at the Institute for Environmental Decisions. It turns out that in the 1930s and 1970s there were already discussions about how long reserves of rock phosphate would last.
85% of the world’s reserves are held by just four countries: Morocco, China, Algeria and the USA. Calculating exactly when those reserves will dwindle is not so simple because there are many different factors that determine how long they might last. Price, supply and demand play a role, but so do the political environment and technological innovation in the mining sector. What is decisive for these calculations is not the amount of rock phosphate that actually exists, but the economic conditions under which it is mined. Because this decides whether a deposit is worth extracting.
It is precisely for this reason that the current debate about the point of peak production is somewhat unhelpful. It simply gives a wrong picture of things. “If we want to deal with the problem seriously, then we have to keep an eye on the whole system and take account of the phosphate deposits that exist in the ground, for example”, says Ulrich. A step in the right direction would be to improve our data so that the discussion can be placed on a more solid footing. All the same, the current literature already offers reliable figures, and these show that today’s deposits should last for some 350 years.
A glance into the past can also be helpful for another reason: “In earlier years, people were already talking about possible measures that might become necessary. But regardless of how important it might be to find new solutions, we shouldn’t reinvent the wheel every time. Instead we should use the knowledge we have already gained, but in a more goal-oriented manner”, believes Ulrich. What is remarkable is that the repeated discussion about the limited amount of phosphate has ultimately led to an expansion of reserves. Other suggestions, however, have not been pursued – such as curbing its use. The consequences for the environment have been fatal, for in many places farmers still use phosphates wastefully, resulting in the unnecessary pollution of rivers and lakes.
And yet there are in fact various approaches that would be feasible. If people in industrialised countries were more conscious about their eating habits, less food would be thrown away. And a more targeted use of extracted fertilisers, coupled with a more effective use of organic fertilisers (i.e., from plants or animals), would not only let us reduce their use and but also reduce environmental pollution. And last but not least, Ulrich sees recycling as a necessity: "If we can recover phosphates from sewage sludge and waste water, then we can create an important contribution to a sustainable use of phosphorus".
Manure and nuclear power plants
But Ulrich also argues in favour of a better use of rock phosphate, and one of her suggestions is controversial. Some rock phosphate contains considerable amounts of uranium. If we were to separate the uranium during processing, we could both produce a more environmentally friendly fertiliser and also secure a longer-term uranium supply for nuclear power plants. This would make sense because there are also only limited reserves of uranium that can be easily mined. The amounts involved are considerable too. In 2010 alone, it would in principle have been possible to gain 11,000 tonnes of uranium from rock phosphate – which is equal to a fifth of the world’s total uranium production. This possibility was also discussed in the 1950s and 1970s, and the necessary processing plants were even built. But when the Soviet Union disintegrated, large amounts of surplus uranium suddenly flooded the markets, so the idea was put on the back burner.
In Ulrich’s opinion, we now need an approach that tackles the problem on different levels. “It would be ideal if all those involved – industry, authorities, NGOs and scientists – were to come together in a dialogue”. This would also be important because fundamental questions pertaining to distribution have to be clarified. In certain parts of the world, local agricultural potential cannot be properly realised because there is a short supply of phosphate fertilisers. Various initiatives have been started recently that aim to tackle the problem on a national and international basis. Nevertheless, Ulrich sees an institutional gap here: “Both the United Nations’ Environment Programme and its Food and Agriculture Organization only see themselves as partially responsible. Ultimately, we are lacking a single institution that would bring everything together and focus existing knowledge on the issue”.
Felix Würsten is a freelance science journalist.
(From "Horizons" No. 102, September 2014)