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Environmental Issues
Going Green

By Alan J Hartley

Solar Energy



Solar Energy, which of course comes from the Sun, falls on the Earth in abundance and it has been calculated that some 89 petawatts of sunlight reaches the Earth's surface, which is almost 6,000 times more than the whole World's 15 terawatts of average electrical power consumption. The problem is not in the quantity of power, but how to harness it. As far back as ancient Greece scientists realised that glass could be used to focus the suns rays to heat water in a bottle. Modern science has developed the idea further to create Solar Furnaces (See separate article) and Solar Heating Water Panels, (See separate article) but a different way of harnessing Solar power has caught the imagination of people the World over.

Photo voltaic power cells convert sun light directly into electricity, but the resulting power needs to be altered, from DC to AC by an inverter, for domestic use. Although systems have a high set up cost they have virtually no running costs and to overcome the installation costs many Governments are offering various financial incentives to manufacturers and the public to encourage take up of installations. This happened in Spain and Germany, who are the European leaders in the field, and created some 10,000 manufacturing jobs in Germany alone. Much of the electricity generated by Photo Voltaic Cells is created domestically, but there are several commercial power stations in both Germany and Spain as well as a 25 mega watt plant in Florida that has over 90,000 solar panels. The Worlds biggest Solar energy plant, that is currently being constructed is in California, will generate 550 MW at a cost of over 1 billion dollars.

Although solar energy is used to generate electricity in more than 100 countries, at the moment this represents a tiny 0.15 percent of global demand for power. It is hoped that increasing demand for Solar will drive down production costs as well as increase research and cell efficiency. Currently cells are made based on Silicon crystals and some toxic metals such as Cadmium. This has led to concerns over the hidden cost of their safe disposal in years to come, but with new reclamation techniques being developed all the time this may not be a problem.

A big problem with Photo Volataic Cells is that they are relatively inefficient and rarely operate at maximum efficiency due mainly to the angle of the sun and adverse weather conditions. Another drawback with the domestic use of AC (after the use of an inverter) energy created with Solar cells, is that the energy usage has to be matched with that created, or else, I believe, equipment may not be powered correctly and may be damaged.  Consequently, the AC energy created is normally fed into the National Grid and can't be used by the householder in the event of a general power cut. However, from a domestic users point of view, if enough of the population with a suitable South facing house roof, have systems installed they can make a valuable contribution to the nations green electricity generation. Prince Charles is a firm believer and has just been granted permission to install a large system on Clarence House in London.

Solar Cells are also proving their worth in remote locations such as on boats, traffic signs and for remote telephones where the DC current is usually fed into a battery to be drawn on later as required, or else used at a constant rate as for irrigation pumps. Developing countries are making more use of solar power generation in some ways than we are in the West. India has introduced a rural lighting program to provide solar powered LED lighting to replace kerosene lamps.

Other more exotic ways that Photo Volataic cells are being employed are to power cars. Indeed there has been a race across Australia for several years now and many more are springing up around the World. A Solar Powered plane has recently spent over 24 hours in the air in continuous flight with all of its power generated by photo cells that created enough surplus in daylight to charge batteries to power it at night. A 14.5 metre Solar Powered ferry runs on the Serpentine lake in London's Hyde Park. The pleasure boat, that carries 42 passengers at some 4 knots, utilises 27 solar panels to generate more than 2KW and has back up batteries that will enable it to travel in total darkness for 20 miles.

Perhaps belonging in the realms of fantasy is one idea to install Solar power cells in the surface of a roadway. The theory is that the road surface is generally free of obstruction to the Sun and if the idea works there is enough roadway throughout the World to generate the World’s electricity.



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Books By
Alan J Hartley