In the lively discussion period following the US premier screening of Sand Wars in Washington DC a couple of weeks ago, and following the showing at the Zurich environmental film festival, there was one outstanding theme – surprise. Which is exactly what I had always hoped for with the book and then with Denis Delestrac's documentary. The fact that sand plays a heroic role in our daily lives and the workings of our planet sets the scene for the – often surprising – fact that sand is not just sand. Anyone who has occasionally looked at this blog and, in particular, the displays of arenaceous diversity in the Sunday Sand posts will appreciate that the stuff comes in a dazzling variety of shapes, sizes and compositions – no two sands are the same. And this means that if you want to make something with sand, whether it’s glass, filters, concrete, golf course bunkers, foundry castings, silicon electronic components, or a host of other things, any old sand just will not do: it has to be the right kind of sand. Concrete, of course, is the most obvious example, given how much of the stuff each of us uses (or has used on our behalf). The fact that the rapid development of Dubai has only been possible through sand imports when the desert dunes are right there, is a surprise. But the fact is that desert sand just will not do for making good concrete.
The range of needs for special sands presents two challenges: how to get the right kind of sand from the place where it naturally occurs to where it is needed and how to ensure that the resources of that right kind of sand are not only sustainable but exploitable without destroying the environment, ecosystems and livelihoods. Meeting these challenges is manifestly failing in many parts of the world, as the documentary describes, and, while it’s easy to see this as a problem of the so-called developing world and that we in the west are far too thoughtful in our approach to environmental and resource management for such issues to arise at home, this is, sadly, not always the case. A notable example is the supply of the specialty sand required – in vast quantities – for the fracking (or fraccing) of oil and gas wells. This is an emotional topic on both sides of the Atlantic and the subject of heated media and social ‘debate’. This is not what my primary focus here is, but I should probably declare my general position: fracking is proven and reliable technology that presents problems only when regulations are loose, regulatory enforcement is deficient, and ‘cowboy’ operators are allowed to flagrantly disregard good engineering practice. The fact that these issues can be, unfortunately, quite often the reality is a justifiable cause for concern – it’s not rocket science to fix but the media frenzy is arguably misdirected. Anyone who would like to discuss this further is more than welcome and I would recommend having a look at the objective report put out last year by The Royal Society and The Royal Academy of Engineering. My point here, however, is specifically about sand.
The technology of hydraulic fracturing involves accessing the oil or gas trapped in essentially impermeable rocks from which they cannot naturally escape. Permeability is induced artificially by water (and yes, also often unknown chemical additives) under extremely high pressures, creating a network of cracks, fractures, through which the hydrocarbons can be persuaded to flow. But creating those fractures is only the start: natural underground pressure would rapidly close them up again – something has to be put into them that keeps them open, and that something is sand. But not just any old sand. It has to be tough and uncrushable pure quartz sand, the grains have to be all of the right size and they have to be smooth and rounded so that they don’t clog up up the fluids or the fractures as they are forced into them. Here is a view of a typical construction sand on the left next to a good frac sand:
The challenge lies in the fact that huge quantities of sand are required for every fracturing operation – often thousands of tons per well. The whole process is shown clearly in this graphic from the Wisconsin Academy:
This demand, along with the enormous volume of water required, not does not frequently feature as an issue in the ‘debate’. With the boom in fracking in the US, demand for the right kind of sand has more than trebled in the last four years – the US Geological Survey estimates that 30 million tons of frac sand was produced in the US in 2013. Where from? Mostly Wisconsin and neighbouring Midwestern states. The seas that covered much of the US more than 450 million years ago deposited, and time and chemistry purified, sands ideal for hydraulic fracturing purposes. Although today these are sandstones, the cement holding the grains together is weak and they can be easily mined and disintegrated back into sand. The scale of the sand-mining industry in Wisconsin and neighbouring parts of Minnesota has escalated dramatically in the last few years to the point where it has clearly become an environmental, social and health issue (the last particularly as a result of the generation of silica dust). At the same time, the industry is a welcome source of employment and state income, but fluctuations in the level of industry fracking activity hardly make for a stable economic benefit. The image at the head of this post is from a recent article by Minnesota Public Radio and shows two views of downtown Winona today and a year ago when the stockpile of sand that became known as ‘Mt. Frac’ filled a vacant lot. It has disappeared not because of the concerns rightly expressed by the local citizens but because of the fall in demand.
As usual, these are issues that are not clearly one that is black-and-white, but they could benefit from a little more awareness and careful discussion – and not only in Wisconsin and Minnesota.
[For further reading, see this Geology.com piece, a recent article in Forbes, and this excellent discussion from the Wisconsin Academy from which includes the two images within the post.]
