The UN has estimated that the global population will grow by two billion people to nine billion by 2050 and as more and more disadvantaged people leave their rural homes to try to find work in their countries' cities the urban populations will double.
Already China and India have several megacities, several of which have among the highest pollution rates in the world.
Global warming and climate change have focused attention on what is called sustainable development, generally defined as a balance between economic growth, human development and environmental protection.
Two of the booming economies of the last twenty years have been India and China and the two have several megacities, with some of the highest pollution rates in the world. None of them could realistically be called models of sustainable development. Much of the urban pollution is because of the concentration and increase in traffic and the emissions that come from petrol and diesel powered engines.
It is understandable that the Chinese and Indian governments resist pressure to contain their rates of growth given that they both still have huge populations of economically disadvantaged citizens and both argue that they should not be made to pay the price for a problem created by the developed world.
Nevertheless both have expressed their concern about the environment and their willingness to play their part in combating climate change wherever possible consistent with their economic aims.
This is where the connection between sustainable development, clean energy technology and rare earth metals is made.
One REM in particular, germanium, is an essential component of lithium batteries, used in many electronic gadgets and particularly for electric vehicles.
One of the biggest problems for electric vehicles (EV) batteries is that they don't hold a charge long enough and the technology needs to improve dramatically so that batteries can store more energy before electric vehicles can provide a viable transport alternative.
One research team has been experimenting with a germanium sub-oxide and initial signs are that it may be possible to improve battery charging by up to three times by using electrodes made from germanium sub-oxide instead of the current graphite electrodes.
If the battery life of electric vehicles can be improved it could be argued that the megacities of Asia as well as those in the rest of the world could then consider switching transport to such vehicles with a benefit to the air quality in their cities and more widely to the planet without sacrificing their efforts to improve the living standards of their populations.
Wafers for solar cells, the production of optical fibre, night vision devices, thermal imaging cameras and in solar panels also use germanium. As is the case with all rare earth metals it has to be extracted from other ores.
It is becoming increasingly clear that progress on sustainable development and clean technologies is going to depend on developing the technology of extraction and increasing the supply.
Although rare earth metals can be found in many places in the world, the bulk of the supply and processing, up to 98%, is currently in China, which has recently been reported to the World Trade Organisation by the USA, Japan and the EU for limiting its exports of them.
In this context a urrent meeting between the US, EU and Japan in Tokyo to discuss developing alternatives to and re-use of rare earths is particularly significant.
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As the global population grows and becomes increasingly urbanised rare earth metals will play an important role in switching to energy saving technology such as solar power. By Ali Withers. http://www.denver-trading.com
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