Image: Model of a single-walled carbon nanotube. Image in the public domain.
It’s hard to keep track of the soon-to-be-implemented technological solutions that will solve our energy and environmental woes by means of nanotechnology – the science of manipulating individual atoms. Solar panels and batteries might be far from optimal solutions now, but nanomaterials will boost their efficiency and dramatically lower their costs. Transporting electricity from solar plants in deserts may not be possible yet, but nanotechnology will bring us cheap superconducting cables and efficient hydrogen storage. Unfortunately, more and more research indicates that nanomaterials might become a severe health problem and an environmental nightmare.
If one reads the news articles and press releases that promise a breathtaking advance in ecotech, one finds that all these claims rely on nanotechnology.
Many key technologies of the coming “ecotech” revolution - the belief that technology can solve the looming energy crisis without giving up our high energy consumption - are evolving at a provocatively slow rate. For example, batteries are an indispensable element of electric cars, but their capacity is limited: if we want to give e-cars the same mileage as gasoline powered cars, the batteries would be bigger than the cars themselves. Even then, it would take many hours to recharge them, and since batteries lose their recharging capacity over time they have to be replaced after some years - making electric cars everything but green.
Ecotech boffins are convinced that this slow progress can be accelerated in a spectacular way. But, if one reads the news articles and press releases that promise a breathtaking advance in superconducters, solar panels, batteries or fuel cells (which can store hydrogen), one finds that all these claims rely on the same technology: manipulating individual atoms, a method known as nanotechnology. All obstacles seem to disappear when ’nano-engineered titanate’, ‘buckyballs’ and (especially) ‘carbon nanotubes’ are put to use.
This does not apply solely to:
batteries: “nanosafe’s Li-ion cells using nano titanate structures instead of traditional graphite give the Lightning GT sports car an incredible 250-mile range, a full recharge time of only 10 minutes, and a life expectancy of 12 to 20 years.” (another example here)
hydrogen: “nanoparticle coatings can boost the efficiency of electrolysis to 85 percent.”
superconducting power lines: “think about underground transmission lines that can revolutionise the power grid.”
but to almost any sustainable technology:
water desalination: “nanotube membranes could reduce the cost of desalination by 75 percent.”
lightweight materials: “a material that is as strong as aluminium alloy, but just half the weight.”
carbon capture : “new nanomaterial doubles CO2-storage.”
low-power computer chips: “the new approach can allow an eightfold increase in the number of transistors that can be squeezed onto a variety of programmable chips, while bringing savings in energy consumption”
energy efficiency: “nanotech heralds new era in heating, cooling and power generation.”
ecopaint: “new pollution eating paint will clean the air.”
self cleaning windows : “the product keeps windows clean from dirt and grime for up to two years - no harmful detergents needed.”
A match made in heaven?
In fact, nanotech and ecotech have almost become synonyms. According to the British Department for Environment, Food and Rural Affairs (DEFRA), nanotechnology could help reduce greenhouse gas emissions by up to 20 percent by 2050, with similar reductions in air pollution. Treehugger, one of the most influential eco-magazines on the internet, dubbed the combination environment - nanotechnology a “match made in heaven”.
Nanotech in the 19th century
History shows that it might be wise to be sceptical of enthusiastic claims. Especially relevant for nanotechnology is the case of asbestos. Starting at the end of the 19th century, asbestos was seen as a revolutionary material due to its versatility, strength, resistance to fire and heat resistance. It soon became widespread in all kinds of building materials and consumer products. Browsing through news articles from those days, one seems to be reading present press releases on nanotechnology. Take this excerpt from the New York Times, for example, dated November 21, 1909:
“Of all the queer materials which nature seems to have provided for no other purpose than that man may show his ingenuity in their use, nothing compares to that mineralogical vegetable, asbestos, which in its native state is both fibrous and crystalline, elastic and yet brittle, a stone, which will float, and which may be carded, spun, and woven like flax or silk. (…). It is absolutely indestructible, no known combination of acids, even, affecting the strength of appearance of its fibre, and the fiercest flames leaving it unscathed. (…). Millions of feet of steam pipes, boilers, are covered with asbestos, which causes them to retain all heat, while the same material forms a frost-proof protection for gas and water pipes.”
In the 1970s, it became clear that prolonged inhalation of asbestos fibres can result in lung diseases like asbestosis or mesothelioma, a rapidly fatal form of lung cancer. Asbestos was banned at the end of the 1980s. Today, there are thousands of companies making a good profit on removing this once revolutionary material out of buildings, machinery and infrastructure. The cost of asbestos-related disease is expected to exceed 200 billion dollar in the US alone.
With this experience in mind, one would assume that today we would investigate the possible harmful effects of new “magical” materials before we implement them. However, this is not the case. At this very moment, there are already more than 600 (identified) consumer products on the market that contain nanomaterials (find a continually updated list here). None of them have been tested for possible negative effects on the environment or on our health, for the simple reason that there are no tests available yet.
Billions of dollars are pumped into nanotech research each year, yet there is hardly any money available for investigating the risks of it (in the US, less than 3 percent of the 1.4 billion dollar federal nanotechnology budget was spent on risk research). Nanoscale silver is the most cited nanomaterial used in the products already on the market (20 percent), followed by carbon (including carbon nanotubes and buckyballs).
As a solution to our energy and environmental woes, “nanostructured bismuth telluride bulk alloys” sounds way better than “say goodbye to cars, plane trips and mobile phones”
Advocates of nanotechnology say that nanomaterials are unlikely to be dangerous, because our world is already full of them, in the form of dust, smoke, sand or sea spray. That might sound reassuring, but it’s not. Firstly, inhaling dust or smoke can be harmful. Secondly, proponents of nanotechnology solely talk about the chemical properties of nanomaterials: carbon is harmless for people, they reason, and therefore carbon nanotubes are harmless, too. Yet, nanomaterials can not be treated as chemicals. The structure of nanomaterials is as important as their chemical properties in defining the health and environmental effects. Asbestos comes in different shapes and sizes, and some of them are much more harmful than others.
At the end of last year, in the journal Nature, 13 nanotoxicity experts called for more research into the potential toxicity of nanoparticles:
“Recent studies examining the toxicity of engineered nanomaterials in cell cultures and animals have shown that size, surface area, surface chemistry, solubility and possibly shape all play a role in determining the potential for engineered nanomaterials to cause harm.”
“This is not surprising: we have known for many years that inhaled dusts cause disease, and that their harmfulness depends on both what they are made of and their physical nature. For instance, small particles of inhaled quartz lead to lung damage and the potential development of progressive lung disease, yet the same particles with a thin coating of clay are less harmful.”
“Asbestos presents a far more dramatic example: thin, long fibres of the material can lead to lung disease if inhaled, but grind the fibres down to shorter particles with the same chemical make-up and the harmfulness is significantly reduced.”
Carbon nanotubes - the poster child of the nanotech revolution - look very much like asbestos fibres (it’s also interesting to note that one of the nanoproducts already on the market is fireproof glass - resistance to fire was the main use of asbestos).
A study that was released yesterday, and will be published in Nature Nanotechnology, showed that carbon nanotubes that look like asbestos fibres, also behave like asbestos fibres. In other words, the wonder material of the 21st century turns out to be carcinogenic. (see also news articles here, here and here).
Just as is the case with asbestos, the dangers of carbon nanotubes do not necessarily appear when the technology is in use. Insulation that contains asbestos does not harm people as long as it’s captured in or between other materials.
Only during manufacture and removal - when the fibres can be released in the air or in the water - asbestos can be deadly (there are exceptions, however, like the use of asbestos in brakes). That means that discarded nanoproducts have to be treated as toxic waste, and that workers producing nanoproducts have to be protected. Today, that is not the case. Andrew Maynard, the author of the study that appeared yesterday, said last year in an interview:
“The materials safety data sheet for carbon nanotubes - which provides workers and safety personel with information on proper handling procedures - treats these substances as graphite, the material used in pencils. But carbon nanotubes are as similar to pencil lead as the soot on my BBQ is to diamonds.”
The risks of nanotechnology are not limited to carbon nanotubes. In April, an American study showed that socks containing nanomaterials (to prevent foot-odour) pose a threat to marine organisms. The socks hold nanoparticle silver, which is the most used element in today’s commercially available nanoproducts for its antibacterial and odour-fighting properties. The researchers simply washed the socks and found that some of them released substantial amounts of nanosilver particles during laundry, which then travel through wastewater treatment systems and into natural waterways, where they can kill fish.
This also means, incidentally, that the socks lose their magical properties after one or several washes and that you will smell his feet again. In December 2007, it was also found that C60 nanoparticles (Buckyballs) are toxic for aquatic species. Conclusion: the three most promising nanomaterials have side effects that make them everything but sustainable. Of course, none of these worrying studies were published on ecotech websites (some even choose to publish another hurrah-article on nanotech today).
Look the other way
It is tempting to close our eyes for these risks, since the trouble will only appear in the far future, as was the case with asbestos: mesothelomia takes 30 to 40 years to appear following exposure. And nanotechnology is an attractive solution, since it would allow us to keep living our high energy consumption lifestyle. As a solution to our energy and environmental woes, “nanostructured bismuth telluride bulk alloys” sounds way better than “say goodbye to cars, plane trips and mobile phones”.
One could argue that the worrying results do not mean that nanotechnology (or ecotech) is dead: the research in Nature Nanotechnology also showed that shorter nanotubes don’t seem to be causing trouble. Yet, engineered nanomaterials come in such an enormous diversity of sizes, shapes, compositions and coatings, that there is an awful lot of testing to be done. That will surely slow down progress in nanotechnology, and make the products more expensive. Unless we decide not to do the testing, of course.