This Gigantic Solar Furnace Can Melt Steel

The furnace concentrates the heat of the sun into a 3,000-degree Celsius beam that can fire ceramics without fuel.

(Image credit: Manuel Litran/Paris Match/Getty Images via IEEE)
(Image credit: Manuel Litran/Paris Match/Getty Images via IEEE)
(Image credit: galano via Wikimedia Commons)(Image credit: galano via Wikimedia Commons)

This giant solar furnace concentrates the heat of the sun into a 3,000-degree Celsius beam that can fire ceramics without fuel.

The IEEE profiled the double-mirror solar furnace at the Mont-Louis citadel in the French Pyrenees as part of a series on historical technology, with an emphasis on the weird and funny. The extraordinary power of this solar furnace was used by French engineer and professor Félix Trombe to conduct experiments on materials at high temperatures, as well as to demonstrate the ability to fire ceramics.

It can direct 50 kilowatts of solar energy into a single point in strong sunlight, heating a few square centimeters to a degree that can melt steel.

(Image credit: Manuel Litran/Paris Match/Getty Images via IEEE)(Image credit: Manuel Litran/Paris Match/Getty Images via IEEE)

The furnace was built in 1949 in the center of the citadel, and was then moved to a location near the Mont-Luis city walls in 1975. Now, it’s used for educational purposes and open to tours.

A successor to the Mont-Louis solar furnace, the Odeillo solar furnace, was opened in 1970 and has a 1,830-square-meter parabolic reflector. It is the largest solar furnace in the world and is used by the French National Center for Scientific Research to test materials that need to stand up to extreme heat, such as thermal shielding for spacecraft or cladding for nuclear reactors. It can also be used for testing how to make synthetic fuels, without creating carbon emissions. Trombe also oversaw construction of the Odeillo solar furnace.

Solar ovens are a zero-emissions way to cook food or heat materials for crafts and ceramics, although they are obviously dependent on the availability of direct sunlight and don't typically store heat efficiently over time.

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