A solar-powered device has achieved temperatures of over 1,000 degrees Celsius in a potentially groundbreaking proof-of-concept for use in heavy manufacturing industries.
Using synthetic quartz crystals to trap solar energy, Swiss scientists harnessed green energy to generate high-intensity heat that could replace fossil fuels in manufacturing altogether.
Temperatures greater than 1,400 degrees Celsius are required for heavy manufacturing like iron ore smelting, and heating kilns for cement and similar products, applications typically serviced by high-quality metallurgical coal and similar fossil fuels.
A new path toward decarbonisation
The cement and steel industries have been making efforts to reduce their carbon impacts through the use of higher quality materials such as magnetite ore, and graphite and other engineered materials to replace traditional and more carbon-intensive options.
This latest breakthrough in solar-generated heat may offer a new pathway toward even greater reductions in carbon emissions, should the technology be refined to meet the higher requirements of those industries.
The researchers used quartz crystal to trap sunlight, attaching a synthetic quartz rod to an opaque silicon disk. The absorber plate was then exposed to the equivalent solar energy of 136 suns, and reached temperatures of about 1,050 degrees Celsius.
Using a heat transfer models, the researchers were able to simulate the experiment under several different conditions, achieving a 70% efficiency of 1,200 degrees Celsius with a quartz-shielded receiver under a concentration of 500 suns of solar power.
“Previous research has only managed to demonstrate the thermal-trap effect up to 170 degrees Celsius,” says experiment author Emiliano Casati of ETH Zurich, Switzerland.
“Our research showed that solar thermal trapping works not just at low temperatures, but well above 1,000 degrees Celsius. This is crucial to show its potential for real-world industrial applications.”
More work to be done
The team is now working to optimise the technology, experimenting with various materials, fluids and gases as well as other forms of heat radiation not limited to sunlight.
“Energy issue is a cornerstone to the survival of our society,” Casati emphasises.
“This study contributes to the development of more efficient solar receivers to decarbonise key industrial processes requiring high heat, such as the manufacturing of cement and metals and the thermochemical production of solar fuels.
“Solar energy is readily available, and the technology is already here. To really motivate industry adoption, we need to demonstrate the economic viability and advantages of this technology at scale.”
The steel and cement manufacturing together account for about 12% of the world’s carbon emissions and are considered two of the industries most difficult to decarbonise due to their requirements for extremely high manufacturing temperatures.