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Advanced Solar Applications

First published June-2010
last update 25-September-2015

Advanced applications are defined here as requiring above 1000 °C, as existing local methods cannot reach this temperature, examples being steel working or refining silica from sand to make photo-voltaic panel. Since existing local methods do not yet reach significantly over 1000 °C, the principle of local construction may not hold.

Where the line is drawn between what is more effective to build on location and at a specialized workshop is difficult to say; only time and experience will tell. And of course, as techniques are developed more and more, what is feasible with local concentration augments all the time, pushing further the definition of an advanced applications.

However, it should be noted that no advanced application is likely to be necessary for life, so even if these sorts of applications were transported long distance, a given community would not be dependent on the applications to survive, and so not vulnerable to a collapse in the supply line. The danger of monopolies would thus be avoided, and the advantage of specialization where effective reaped.

It should also be understood that the transportation of such applications, to transform a resource on location, would represent a nearly insignificant volume compared to the transportation of those resources themselves, as is the current practice in the global economy.

However, applications are usually, if not always, relatively small compared to the concentrators that provide the energy, and the sun energy available per square meter is the same for all solar technologies (a complicated solar concentrator can’t generate more sunlight). So, even for an advanced application it is probably still far more effective to build the concentrator close to location. Also, it can quickly becomes more effective to add 10% more surface area than proportional increase the efficiency of the design, as even for advanced applications a relatively simple solar concentrator would likely remain effective.

Existing advanced concentrators can melt steel and even rock, but they expensive experimental units. For the foreseeable future extreme temperatures will likely continue to be achieved with fossil fuels, but this may not be environmentally devastating if everything that can be easily powered with solar concentration is powered with solar concentration. Domestic energy is far from requiring temperatures of above 1000° C and it is estimated that 80% of energy consumed in industry is to run processes below 200 °C. Though there is probably no solution to maintain the global transportation system as we know it today, which is powered by over 97 % fossil fuels, we humans can easily live without such a transportation system as we have for the hundreds of thousands of years before the internal combustion engine.

However, that all domestic heating and the large majority of industrial energy is way below 1000 °C means that most every type of object produced today can be produced locally with solar concentration, from roasting produce to making paper, traditional mortar and steam forming wood. And if this is achieved, we will find that what is currently difficult to produce with solar concentration is manageable with the remaining fossil fuels that exist as well as with solar-charcoal, which can reach well above 1000 °C.

However, even if steel and glass working continue to be powered by fossil fuels for the time being, it is still far better to first power then as much with solar concentration as possible, and start designing and experimenting to reach 100% solar powered. Especially with ceramics, which in many places in the world is currently produced with inefficient charcoal and oven methods, often in desertifying regions, a solar-charcoal hybrid oven can have a significant impact.

Ceramics
Pottery and other ceramics require temperatures of at least 1000 °C to harden. Where charcoal is used to fire the ovens there is a huge consumption of wood: first because half the wood is burned to turn the other half into charcoal, and second, the ovens are fairly inefficient and so consume vast amounts of charcoal, and third, ceramics is an energy intensive task regardless of the methods used.

Though a 1000 % solar economically feasible ceramic oven may take a few years of serious development, it is simple with existing methods to first make the charcoal with solar energy, reducing wood consumption by half, and second heat the oven as much as is possible with solar energy, the difference being attained by burning charcoal.

Steel and Glass Smelting
Though iron melts at only slightly more than what is necessary to make ceramics, to make steel requires a mastery of the heating and cooling processes (unlike aluminium which has no complicating factors to melt and reform), and so we must consider steel smelting a more advanced application than even ceramics, regardless of a proximity in temperature.

Whether a hybrid system with charcoal can be practical would require some experimentation. For now, we can discuss what it would take to adapt existing local solar concentration techniques to achieve temperatures approaching 2000 °C. More precision is required than previously discussed.

The most precise concentrators of the world are double reflection, where a parabolic concentrator is stationary on the ground and a (or multiple) heliostats (flat mirrors that can track the sun) reflect light into the concentrator. As there are two reflections, not only does this increase material and cost, but it requires even greater precision of both reflectors, as any error becomes amplified. Though for extremely advanced applications, such as refining silicon, this sort of concentrator may be necessary, we should first push existing methods as far as possible.

Written by Eerik Wissenz.
Contact:
decent@nym.hush.com

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