Friday, May 04, 2007

Thermal Solar Power.

An array of 600 mirrors has been installed in a field outside Seville, in southern Spain, in an adaptation of the solar-furnace. I am familiar with the latter from working at the Paul Scherrer Institute in Switzerland, with a power output of just 40 kW, but when the bank of mirrors is positioned almost at 90 degrees to the horizontal, the immense energy can be felt instantly by anyone walking past it. The Spanish installation generates 11 MW, and focuses the Sun's rays onto a boiler (a network of pipes) positioned on top of a concrete tower 40 storeys high. Set in the midst of the Andalusian countryside, the thermal solar-power station must be quite an impressive sight, basking in the reflected sunlight.

It is indeed the first of its kind to operate commercially in Europe - i.e. it is not merely a research installation - and its operator, Solucar, announces proudly that it produces no greenhouse gases. True, as is that frequently cited advantage of nuclear power, but there is obviously a "carbon debt" to be paid-off, incurred in crushing rock to make the concrete and in the fabrication of the mirrors; however, the plant should run for years and certainly produce a lot less CO2 than a conventional gas or coal-fired station. This comparison has a further note, in terms of the relative generating capacity of the different technologies, namely that a standard electricity-generating station has an output of around 1 GW, i.e. 1,000 MW. Hence, the thermal solar-powered plant produces just about 1% of that. Put differently, it would take one hundred such installations for each gas or coal-fuelled plant it might be desired to replace by this sustainable technology.

As I have stressed over the putative hydrogen economy, the scale of engineering required to implement thermal solar-power on a comparative level with that which we currently enjoy from fossil-fuelled plants (and nuclear, especially in France where it produces 80% of the nation's electricity) would be truly collosal. The Spanish plant is undergoing a phase of development, and more fields are being cleared into which to install further banks of mirrors with the ultimate intention of providing enough electricity to meet the requirements of 600,000 people, which coincidentally is the population of Seville. In my opinion, we will need all the renewable energy we can lay our hands on, in order for human civilization to survive in the post-oil era that is at hand, but I think this technology will contribute a fairly minor component to the final energy mix, that I wrote about in the very first of these postings back in December 2005.

Who occupies centre stage in the new world order must follow the kind and amount of resources that each country ultimately has. In saying this, normally it is gas, oil, coal and uranium that is meant, and yet it might prove that an especially valuable and unlimited resource is available to the sun-kissed lands of the Mediterranean and Africa. If sufficient of thermal or photovoltaic generating capacity could be installed in sunnier regions, the electricity thus generated could be wired-off to the cloudier European climes. However, for any serious quantity of solar-power to be inaugurated, it is necessary to begin the process now, while we still have sufficient of our existing resources of oil and gas to do the job. In 10 years it may be too late to introduce any of the alternatives that are currently being speculated upon.

Related Reading.
"Power station harnesses Sun's rays," by David Shukman.

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