Solar power generated enough heat to power a steel furnace

Scientists have used solar power to heat an object to 1,800 degrees Fahrenheit (1,000 degrees Celsius) — hot enough to power a steel furnace. The proof-of-concept study, published May 15 in the journal Device, demonstrates how solar energy could replace fossil fuels in high-temperature manufacturing processes, such as smelting steel.

To manufacture materials like glass, cement and ceramics, raw materials are heated to above 1,800 F (1,000 C). Currently, using solar energy to reach these scorching temperatures is costly and inefficient, so carbon-based energy like oil or coal are typically used to power the furnaces in which these materials are made.

These industries are responsible for around 25% of global energy consumption, researchers wrote in the study.

"To tackle climate change, we need to decarbonize energy in general," corresponding author Emiliano Casati, a scientist in the department of mechanical and process engineering at ETH Zurich in Switzerland, said in a statement. "People tend to only think about electricity as energy, but in fact, about half of the energy is used in the form of heat." 

Scientists have previously explored solar receivers, or heating systems that convert solar radiation into heat via sun-tracking mirrors, but that Technology struggles to break the 1,800 F barrier. 

In the new study, Casati and his team drew upon a property called the thermal-trap effect. Essentially, semi-transparent materials strongly absorb sunlight, re-emitting it as heat. 

So the researchers shined incoming solar radiation onto a synthetic quartz rod that trapped the heat. They then attached it to an opaque silicon dish, which absorbed the heat from the crystal.