February 2007
Concentrated Solar Power: The Answer To The World’s Energy Supply Problems?
Considering its potential implications, it is surprising that there is not a greater knowledge of Concentrated Solar Power (CSP). CSP utilises simple technology to efficiently harness one of the Earth’s most abundant renewable sources, the sun’s heat, to generate electricity.
Two German scientists, Dr Gerhard Knies and Dr Franz Trieb, both of the Trans-Mediterranean Renewable Energy Cooperation (TREC), calculate that covering just 0.5% of the world's hot deserts with CSP would provide for the world's entire electricity needs, with the technology also providing desalinated water to desert regions as a valuable by-product, as well as air conditioning for nearby cities.
What really sets CSP apart from other more well known forms of renewable energy generation is the geopolitical location in which it can best be sourced. CSP works best in hot deserts, an abundance of which can be found in some less economically developed countries such as those found in Africa and the Middle East. What is more, there are hot deserts within 3,000 miles of 90% of the world’s population.
As CSP harnesses the sun’s heat directly, it is a carbon-free electricity generating process. It is cleaner (with no waste streams) and safer than other forms of electricity production and far less likely to be affected by geopolitical concerns (such as the stock-piling of supply as can be seen with fossil fuels, or the potential terrorist threats associated with nuclear power generation).
In addition to environmental benefits, the cost of CSP generated electricity is low. Nuclear power costs anywhere between 5p and 8p per kWh, with new power station under construction in the United States expected to deliver at half that price. However in 2003 The National Academy of Sciences, through research from the engineering and analyst firms Sargent and Lundy, showed CSP, with a free, renewal and infinite supply to be viable with costs of 4-6 cents (US) per kWh for solar troughs.
CSP is not new; a plant in the Mojave desert in California has been successfully, cleanly and cheaply generating electricity for the past 15 years with others being built in Nevada, southern Spain and Australia.
Such is the potential for CSP, the Trans Mediterranean Renewable Energy Cooperation (TREC) have put forward a cooperative plan for powering Saharan countries and the EU using a network of low loss grid lines linked to very large CSP schemes in the Sahara. They have suggested that an area of 250 sq miles in the Moroccan-Algerian Sahara could generate all of Europe's electricity needs. An area of 450 sq miles could generate our global energy requirements as projected for 2030. With the installation of DC power lines to deliver electricity across such a network, less than 10% wastage through transportation could be expected, potentially making such a scheme viable. This is not the case using the current AC network currently found across most of Europe.
Despite such potential, on being elected in 2000 the Bush Administration requested the termination of CSP. Even if the Trec network turns out to be a pipedream, CSP is surely worth further investigation as even if only some of the suggestions made by Trec are found to be viable, CSP could go a long way to helping combat the growing climate change problem that we are all increasingly aware of.
THE SCIENCE BEHIND CSP
There are different forms of CSP but have in common the use of mirrors to concentrate the sun's rays on a pipe or vessel containing some sort of gas or liquid that heats up to around 400C (752F) and is used to power conventional steam turbines.
The mirrors are very large and create shaded areas underneath which can be used for horticulture irrigated by desalinated water generated by the power plants. The cold water that can also be produced for air conditioning means there are three benefits. Combining this triple use of the energy has lead to some estimates of CSP being 80% to 90% energy efficient.
This form of solar power is also attractive because the hot liquid can be stored in large vessels which can keep the turbines running for hours after the sun has gone down, avoiding the problems associated with other forms of solar power.
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