A team of scientists has transformed coffee waste into a material that is as effective at insulating as materials currently used in construction. The advantage of this material, produced from renewable sources rather than fossil fuels, is that when it needs to be disposed of, it is biodegradable.
Scientists are discovering more ways to use used coffee beans. Recently, its addition to concrete and other paving materials, its use to remove herbicides from the environment and even the extraction of new pharmaceutical compounds had already been analyzed.
A new one, published last month in the magazine Biocharinvestigated the extent to which coffee beans could function as a thermal insulation.
According to , the coffee beans used were initially dried in an oven at 80ºC for a week. They were then cooked at higher temperatures to produce a carbon-rich material known as biochar.
The biochar was then treated with environmentally friendly solvents and mixed with a natural polymer called ethylcellulose.
The polymer stabilizes the biochar, while solvents are added to prevent the polymer from clogging the material’s pores — which trap air, an effective insulator against heat.
It is known that materials with conductivity to 0.07 watts per meter per kelvin are considered insulators. The best summer of the coffee-based composite showed thermal conductivity of just 0,04 W/(m⋅K).
In laboratory tests, researchers placed a variety of insulating materials, including coffee-based ones, under a solar cell and measured the air temperature in a chamber below the cell.
This model reproduced the way insulation blocks excess heat radiated by solar panels, preventing it from penetrating roofs and heating homes.
Sung Jin Kim, Seong Yun Kim
In a laboratory experiment, the researchers placed their new material (EC/SB700/PG-25) under a solar cell and measured the temperature
Thus, the performance of the new material was comparable to that of expanded polystyreneone of the best insulating materials currently sold.
The difference, however, is that polystyrene is a synthetic polymer made from fossil fuels, so its production and eventual disposal are much more harmful to the environment.
The researchers suggest that this material could be better used to insulation in buildings, keeping the interior cool even when the sun’s rays are intense.
