Category Archives: Solar Energy

Solar Energy

Manual heliostat

The first steps towards the manual heliostat. A couple of square meters for test purposes must be doable by hand. East west the mirrors can simple pivot around their base and up and down is accomplished by a screw-thread.

backreflector
The back reflector
backside manual heliostats
backside manual heliostats
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Little 30 x 30 cm tile mirrors
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near the focus

With 6 mirrors the open test cell reached already 80 degrees Celsius. With the back reflector the temperature went over the 100 degrees Celsius.

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Heat Storage

When sunshine is intermittent through clouds it’s still possible to use solar heat by forming a buffer. Heat storage in molten salts have been studied since the early 1900s. Molten salts have a great heat capacity, act like a fluid and can get very hot. Most of the studies in the past have been concentrated on energy generation with concentrated solar power-plants and nuclear reactors. The pumping and heat exchangers made it very complicated and expensive. For pyrolysis we only need a well insulated pool where the pyrolysis chamber in can be submerged. For the pyrolysis process we need a temperature between the 400 °C and 650 °C. Higher temperatures can speed up the process, it take a while before the whole pyrolysis chamber is heated up. Higher then 800 °C makes it difficult to work with, stresses, wear etcetera become to great.

801 °C    Sodium Chloride
993 °C    Sodium Fluoride
910 °C    Zirconium Fluoride
271 °C    Sodium Nitrite
308 °C    Sodium Nitrate
714 °C    Magnesium Chloride
661 °C    Sodium Iodide
747 °C    Sodium Bromide
772 °C    Calcium Chloride
790 °C    Potassium Chloride
851 °C    Sodium Carbonate
723 °C    Lithium Carbonate
891 °C    Potassium Carbonate

Even molten metals can be used to store solar energy.

630 °C   Antimoon
639 °C   Magnesium
660 °C   Aluminium

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