Following a directive from the EU on how to tackle climate change, where, by 2020, 15% of all the energy the UK uses must come from renewable sources, there has been a profusion of wind-farms around the country, and wind-swept Cornwall is now beginning to look like a giant pin-cushion.
There is much debate on the effectiveness of wind turbines but I have been particularly interested in their construction, and life-cycle analysis, which quantifies to what extent they are a totally clean form of energy. In this sense we have to consider not only the emissions produced while they are in operation, but also the contamination and environmental impact resulting from their manufacture and the future dismantling of the turbines when they come to the end of their working life.
In this respect, a paper by Martinez et al, in the Elsevier peer-reviewed journal Renewable Energy (2009) analyses the real impact that this technology has if we consider the life cycle, quantifying the overall impact of a wind turbine and each of its components. The wind turbine is analysed during all the phases of its life cycle, from cradle to grave, with regard to the manufacture of its key components, transport to the wind farm, subsequent installation, start-up, maintenance and final dismantling and stripping down into waste materials and their treatment.
They conclude that there is an environmental benefit in starting up and running wind farms, and that the biggest environmental impact comes from the foundation, due mainly to the cement. The nacelle is the heart of the turbine and inside it carries the technology required for converting kinetic energy into electricity. Hence it is the most complex component, made up of a series of elements which are widely differing in nature. Each of these elements has its own associated technology and manufacturing processes, which certainly makes the study of the nacelle as a whole more complicated. The main environmental impact shown by the study is that of the cost in copper. This metal has an enormous value and environmental impact, although it has the advantage of being recyclable.
Although this is a very comprehensive report, they omit the life cycle analysis of a crucial component within the nacelle- the powerful direct-drive permanent magnet generator, which contains a critical rare earth element, neodymium. Neodymium is commonly used as part of a Neodymium-Iron-Boron alloy (Nd2Fe14B) which, thanks to its tetragonal crystal structure, is used to make the most powerful magnets in the world. It has been used in small quantities in common technologies for quite a long time – hi-fi speakers, hard drives and lasers, for example. But only with the rise of alternative energy solutions has it really come to prominence, for use in hybrid cars and wind turbines. A direct-drive permanent-magnet generator for a top capacity wind turbine would use around 2 tonnes of neodymium-based permanent magnet material.
Neodymium is found most often in monazite and bastnasite. Due to the fact that these minerals also contain lanthanides and other rare earth elements, it is difficult to isolate neodymium. The first isolation process involves extracting the lanthanides and metals out of the ores in their salt form. This step is carried out using sulphuric acid, hydrochloric acid, and sodium hydroxide. To further isolate the neodymium from other lanthanides and metals, procedures such as solvent extraction and ion exchange are used. Once neodymium has been reduced to its fluoride form using these processes, it can be reacted with pure calcium metal in a heated chamber to form pure neodymium and calcium fluoride. Some calcium contaminants remain in the neodymium, and vacuum processes are used to remove any of these contaminants. It is an expensive and potentially environmentally harmful process.
In a recent posting (February 1st), it was noted that China produces over 90% of the world’s rare earths, and that Beijing’s export reductions in recent years have forced high-tech firms to relocate to China. An article in a UK newspaper claims to have uncovered the distinctly dirty truth about the process used to extract neodymium: it has an appalling environmental impact that raises serious questions over the credibility of so-called green technology.
According to the report, hidden out of sight behind smoke-shrouded factory complexes lie vast, hissing cauldrons of chemicals in tailing lakes that are often very poorly constructed and maintained; throughout the extraction process large amounts of highly toxic acids, heavy metals and other chemicals are emitted into the air that people breathe, and leak into surface and ground water.
The report concludes that whenever we purchase products that contain rare earth metals, we are unknowingly taking part in massive environmental degradation and the destruction of communities. It is a real dilemma for environmentalists who want to see the growth of the renewables industry but we should recognise the environmental destruction that is being caused while making these wind turbines.
So, what are your opinions, on wind-turbines and the economic and human costs of extraction of neodymium?