Regular readers know how intrigued I am with innovative technology and what it can do for us. But, what I like the most is when new twists are found for old ideas.
Regular readers know how intrigued I am with innovative technology and what it can do for us.
Researchers all over the world are constantly coming up with new technological gizmos that are fun to play with and might even be useful.
But, what I like the most is when new twists are found for old ideas.
Consider the Fresnel lens, something that has been around more than 180 years.
Now, we learn, it might be at the core of a solar heating system meant for installation in roof or curtain-wall assemblies.
Some folks carry a credit-card sized Fresnel lens in their wallet for occasional help with the fine print in a document or with a menu in a dimly lit restaurant.
These are mass produced things, stamped or moulded out of transparent plastic. They are also often used in overhead projectors of projection televisions, although they degrade the image somewhat.
They were first invented by French physicist Augustin-Jean Fresnel, who designed them to replace the heavy, expensive lenses used as beacons in lighthouses.
The first ones, made of glass of course, went into service in 1823, and Fresnel lenses are still mounted in lighthouses around the world.
The need to design products that help us reduce carbon emissions has got scientists all over the world busy and one small group at Spain’s University of Lleida hit upon a way to use Fresnel lenses in solar power modules that can be integrated into a building’s roof or curtain walls.
Like so many good ideas, this one is, at heart, really simple.
Concentrating solar power (CSP) devices usually use parabolic mirrors to focus the sun’s light on collectors and use the energy to create steam to drive a turbine.
Such units, because of their size, tend to be found on places like the desert areas of the American southwest, or the high, sunny central plains of Spain.
But Daniel Chemisana, Manel Ibáñez and Joan Ignasi Rosell, wanted a device that collected the energy right where it was needed.
They hit upon the idea of using a lens instead of a mirror to concentrate the light.
But, they needed a curved lens with a fairly short focal length that didn’t cost an arm and a leg to manufacture.
They hit upon the idea of using a Fresnel, cheaply made from easily moulded acrylic material, tough, but easy to replace should it be damaged.
The short focal length of the lens means it can be placed close to the linear photovoltaic array that collects the energy, which can then be used to generate electricity, or to heat a building.
The modules have a solar concentration of 10 suns, which means that it needs only a tenth part of a standard system’s active surface to produce the same energy.
The reduction in the surface area implies a considerable reduction in cost when compared with conventional solar arrays.
Having accomplished the scientific aspects of their work, the researchers then set about making it practical to install in a building.
They hit upon the idea of making the modules small enough that they can be installed in roofs and in openings in curtain walls or as part of the railings in terraces.
Since the system is made up of small modules, it can be scaled down for a private home, up to a small commercial building or way up to a large building.
The researchers believe they can achieve over-all efficiency exceeding 60 per cent — that is, of the total solar energy that is gathered by the system, 60 per cent or more is converted to usable energy.
The figure looks high, but if they succeed, they’ll have a winner.
The system is patented in Spain, and applications have been made for international patents.
Korky Koroluk is a regular freelance contributor to the Journal of Commerce. Send comments or questions to editor@journalofcommerce.com
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