They sound like superheroes from a Hollywood science-fiction movie: neodymium, promethium, dysprosium and europium. And the comparison isn't actually all that far fetched, for these elements belong to a group of metals that many scientists--and even more prospectors--believe holds the key to a carbon-free world.
Referred to as rare earth elements, these metals are little known outside the industries that are devouring them, or those who can still remember the periodic table they learned by rote at school. Yet the unique magnetic, conductive and luminescent properties of these 17 metals- 15 lanthanides, along with scandium and yttrium--are underpinning the world's switch to green technology.
Magnets based on rare earth elements are used to make electric motors and generators that are smaller and lighter but as powerful--or more so than those based on iron, and have powered the shift towards hybrid cars. Neodymium is the key component of an alloy used to make the high-power, lightweight magnets for electric motors in the Toyota Prius, Honda Insight and Ford Focus. These magnets preserve their magnetic properties even at high temperatures--something they can also do for the generators incorporated into wind turbines.
Tiny quantities of dysprosium can make magnets in electric motors lighter by 90 per cent, while terbium--which is soft enough to cut with a knife--is a key component of low-energy light bulbs, which use 80 per cent less electricity than traditional incandescent globes. Another rare earth metal, lanthanum, is employed to make the energy-efficient petroleum-cracking catalysts used in modern vehicle engines.
'Rare earths are indispensable,' says Mark Smith, chief executive of Molycorp Minerals, which is mining these elements at Mountain Pass in California. 'The technology is just starting to wake up to the potential for rare earths--their use is growing phenomenally. There are tremendous opportunities, and their application is really only just being understood.'
Green energy may be driving the interest in rare earths, but they are also found in a mind-boggling range of everyday items. Pick a modern device and you'll find rare earths inside, from superconductors, mobile phones and thin-film solar panels to catalytic converters. Virtually all polished-glass products, from ordinary mirrors and eyeglasses to precision lenses, are finished with an oxide of the rare earth cerium, while colour cathode-ray tubes and liquid-crystal displays used in computer monitors and flat-screen televisions employ europium. Lanthanum is key to modifying glass-crystal structure and refraction, stimulating advances in high-tech digital and video cameras.
Miniaturised multi-gigabyte portable disk drives and DVD drives wouldn't exist without magnets made from alloys of rare earths such as neodymium, samarium, praseodymium, dysprosium and gadolinium. Another metal, erbium, possesses optical properties that enable fibre-optic cables to transmit signals over long distances.
Rare earths are also deployed in medical equipment. Lanthanum phosphors in X-ray fihns and lasers reduce radiation doses by three quarters, and the element is also essential to MRI and CAT scans.
Arguably, the use of rare earths has been propelled as much by US Army research as by green technology, and military applications include precision-guided weapons, night-vision goggles and range finders. Yttrium is used in laser crystals specific to military communications, while the notorious 'smart bombs' use neodymium-iron-boron magnets to control direction when dropped from an aircraft.
'We've engineered rare earths into critical aspects of our modern technology,' says Jack Lifton, a consultant and expert on rare earth metals. 'Almost every small electrical motor in our culture--from the hard drive in your computer to the speakers in your Blackberry--contains rare earths. …