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Wednesday, 9th December 2009

The potential of renewables

The World Meteorological Organization's Greenhouse Gas Bulletin 2008 released on 23 November reminds us once again the imminent carbon dioxide issue. The latest concentration is 385 parts per million (ppm), up 2 ppm from the previous year.

For the past 10 000 years, carbon dioxide levels stayed at about 280 ppm till the start of the industrial revolution in the late 18th century. The new figure represents an increase of 105 ppm, or 38%. The increase primarily arises from: combustion of fossil fuels such as gasoline and coal, deforestation and land use change. Burning of fossil fuels adds carbon dioxide to the atmosphere from sources hitherto buried underground, while deforestation and land use change cause a reduction in plant life which acts as a carbon sink through photosynthesis.

So what can we do? In his 2006 review on the economics of climate change, Sir Nicholas Stern pointed to a cost and risk on par with a 5% loss in global GDP each year if nothing is immediately done to slow down global warming. On the other hand, it only costs the world 1% of GDP if action is quickly taken.

In a New York Times article in September this year, Professor Paul Krugman, winner of the Nobel Prize in economics in 2008, also said that a significant reduction in greenhouse gas emissions would only add a small cost to household expense.

But where and how this 'cost' should go? An article in the November 2009 issue of Scientific American (the 'article') discusses the potential of renewable energies in meeting the world's energy needs. It points out that at any given moment the world requires a maximum of about 13 terawatts (TW, i.e. 12 zeros), and this is expected to increase to some 17 TW by 2030.

How much of this is renewable energy? Currently, wind and solar power are together producing a paltry 0.03 TW, or 0.2% of the current requirement. While visiting the Observatory last month, Prof. Kai-ming Ho of Iowa State University, USA, related that all the solar energy falling upon the Earth in an hour alone is sufficient to power the whole world for a year. There is thus tremendous room for development.

The article evaluates the potential of renewable energies, in particular wind and solar energy, and estimates that excluding places such as oceans, mountains and other inaccessible areas, the potential for wind and solar power is about 60 and 600 TW respectively, giving a total of 660 TW. Taking a conservative approach, if we can just extract 5% of it, i.e. 30 TW, the world would even end up with surplus energy. The world will become much better, with no additional greenhouse gases and thus no further warming.

The issue with manufacturing a large quantity of wind turbines and solar panels, however, is the attendant rise in demand for rare metals which are required for these green technologies. What scientists can do, and is doing, is to research alternative or better materials to ease the demand.

Another development involving solar energy is the increasing popularity of solar thermal collectors which convert sunshine into heat, as opposed to solar panels which turn solar energy into electricity. A consortium of German corporations is currently planning a large number of solar thermal collectors in the Sahara with a view to supporting 15% of Europe's electricity needs by 2050.


Figure 1     Solar thermal collectors (courtesy of Ho Fung School, Hong Kong)
Figure 1     Solar thermal collectors (courtesy of Ho Fung School, Hong Kong)


Mr Ban Ki-moon, the U.N. Secretary-General, proposed in an article on the Washington Post in 2007 that humankind is experiencing a major transition into a 'green' economy, where through concerted effort we can face up to the challenge of climate change in a relatively inexpensive but sustainable way.

Green technology is now coming to the fore. Its adoption boosts a company's image. More often than not, procurement in the near future may demand a green label or strict low-carbon or carbon-neutral standards. Green technology can therefore be, and probably is, a very good choice when it comes to combating climate change and seizing new business opportunities.


B.Y. Lee



Last revision date: <17 Jan 2013>