we produce the Linear Mirror II
One year ago we published the first results on solar carbon. We showed, that one can use solar energy provided by the Linear Mirror II in order to transform cheap kinds of biomass (straw) to charcoal and gas. The tests were very simple, just to explore whether it is possible at all. This month we studied the problem of solar pyrolysis in more detail. The most important issue was the efficiency of the process: with solar radiation it is easy to transfer heat energy to the outer surface of a pyrolysis retort. But the transmission of the heat energy from the inner wall of the pyrolysis container into the material is less trivial, because straw for instance is an excellent thermal isolator. For our new studies, we have improved the pyrolysis device. It has a larger irradiated surface and more volume. The tests went very well: the pyrolysis process was much faster now, and much more homogeneous. We worked again at temperatures up to 300 degrees.
It is clear from those experiments, that solar pyrolysis will become a very simple and safe industrial process. That does not sound very exciting. But consider, that up to today there is little industrialization in the pyrolysis of simple biomasses. A pyrolysis device, which automatically and without constant supervision transforms straw (or other cheap kinds of biomass) to carbon, does not exist nowadays as an industrial product. The economics of solar pyrolysis looks good, too: we can transform 1 ton of straw to 300 kg of solar carbon. 1 ton of straw costs about 100 Euro, that is 0.3 Euro/kg of solar carbon. That corresponds about to the price of fossil carbon or gas. Prof. Barbieri and his team (Univ. Trieste) have analyzed the solar carbon. They f ound that it has a heating value of 27.2 MJ/kg. That is as much energy as you get from fossil carbon of good quality. That definitely means, that solar carbon can be used to substitute fossil coal. The only difference between solar carbon and conventional coal is, that solar carbon is CO2 neutral. You can consume as much of it as you want, without heating up the planet. And of course, you can not only use solar carbon for all applications, which use fossil coal, but you can also transform solar carbon to other materials, like liquid fuels, for instance, there are many old and well known processes for doing that, like Fischer-Tropsch, Haber-Bosch etc. In meanwhile, grass has grown around the mirror at Pordenone, it looks much nicer now: