On the table is a mobile phone. Which metals used in it are in danger of running out quickly? "Not many," says Theo Henckens, who received his PhD in October for a study on scarcity of some 60 metals. "You would think of the so-called rare earth metals. But these are geologically less rare than their name suggests. They include some gold, which does get scarce quickly. But gold is an exceptional case, because anthropogenic gold reserves are large."

Metal

If the extraction of raw materials is by definition finite, how can you still use them sustainably?

On the table is a mobile phone. Which metals used in it are in danger of running out soon? "Not many," says Theo Henckens, who completed his PhD in October on research into scarcity of some 60 metals. "You would think of the so-called rare earth metals. But these are geologically less rare than their name suggests. They include some gold, which does get scarce quickly. But gold is an exceptional case, because anthropogenic gold reserves are large."

But there are also metals whose ores will be exhausted in the foreseeable future, Henckens said. Molybdenum, for example, used in high-grade steel; antimony, used in many electrical appliances. The extractable reserves of zinc and gold will also be exhausted this century if we continue like this.

They are often pessimists who question whether the earth contains enough raw materials for everyone - now and in the future. But Henckens is not. His thesis, Managing raw materials scarcity , recalls the report of the Club of Rome, a group of scientists who saw the limits of growth looming as early as 1972. Henckens, too, was quite pessimistic when he started his PhD research. "I grew up with the Club of Rome," says the 68-year-old chemical engineer in his home on the outskirts of Bosch and Duin. "Out of concern and curiosity, I wanted to find out for myself."

The Club of Rome assumed proven reserves of raw materials. "That is a pessimistic starting point," says Henckens, who worked for years at environmental consultancy DHV. "Proven reserves rarely extend beyond a few decades. After all, that's how long mining companies look ahead. They don't look further if they have a reserve for the next 30 years, exploration costs are too high for that."

Henckens looked at extractable reserves. He used figures from the United Nations Environment Programme (UNEP) and the US Geological Survey (USGS) on the presence of all kinds of metals in the upper kilometres of the Earth's crust. "The vast majority of these are not extractable, or at least not easily extractable, because the concentrations are too low. Only a maximum of 0.01 per cent of all metals are concentrated in ores."

Henckens took 2010 figures as a basis and assumed an annual growth rate of about 3 per cent, which he said is mainly in developing countries. In western countries, growth is largely over, he says. "When a society gets richer, people start spending more money on things like healthcare, tourism or theatre. A car costing a tonne does not use ten times as much material as a 10,000-euro car. In Western countries, you therefore see a decoupling of resource use and economic growth. Around 2050, in my scenario, developing countries will also have reached that point."

Sustainable use

The question Henckens posed was: if the extraction of raw materials is by definition finite, how can you still use them sustainably? The Brundtland report (1987) defines sustainable development as "development that meets present needs without compromising the ability of future generations to meet their needs". Nicely phrased, but what does it mean in practice?

"I chose a thousand years. That is how long raw materials have to be extractable to speak of a sustainable rate of extraction," Henckens said. "It stands for 'very long', but it is arbitrary. A hundred years is too short, then our grandchildren will still be alive. If I had chosen ten thousand years, you can hardly use anything now."

Henckens concluded that that thousand years will not be reached for a number of metals. Antimony will run out in about 30 years. Molybdenum and zinc will be available for another eighty years or so. "You would expect the price of those scarce minerals to go up faster. But viewed over a longer time, there is no significant difference between the price increase of geologically scarce and non-scarce minerals. So that means the market is not doing its job properly."

Henckens wants to give the market a push with an international commodity agreement. At its core is a reduction in the extraction of scarce raw materials so that they remain in supply for at least another thousand years. Countries where mining is curbed should be compensated for this, he believes. "With such a quota, the price of raw materials is likely to rise. Companies will be more likely to look for alternatives. And there will be more recycling. Now primary material use, i.e. directly from a mine, is often cheaper."

In the raw materials agreement between the Dutch government and industry, which comes into force on Tuesday, it has been agreed - on a voluntary basis for now - to reduce the use of raw materials by half by 2030. "Far too general," Henckens believes. "Let's focus it on substances where the critical limit is almost reached. Why worry about aluminium, for example, which we can still use for more than 20,000 years."

Some substances are easy to replace, says Henckens. "About half of all antimony is used in flame retardants, for example in plastic housings of electronics. There are excellent alternatives for that. Now those housings often end up in the incinerator and then you lose the antimony. Of all the boron, 40 per cent is used in glass wool. But glass wool can be replaced by stone wool. That is nothing more expensive and does not need boron."

That does not apply to molybdenum, a necessary ingredient in very high-grade stainless steel, for example for offshore wind turbines. "In his thesis Materials and Energy , René Kleijn concludes that the amount of molybdenum needed to switch from fossil energy to wind and solar power is about equal to the entire current production. And as far as I know, we don't have an alternative yet."

This article appeared in the NRC Handelsblad of Monday 23 January on page 11

https://www.nrc.nl/nieuws/2017/01/23/zink-en-antimoon-zijn-bijna-op-6343887-a1542434