A new way to remove dangerous build-ups of ice without using electrical power or chemicals has been developed by scientists.
Researchers say the new method – inspired by the sun – could prevent freezing on aeroplane wings, wind turbines, power lines, and other surfaces damaged by ice.
The new material, which can be used in the construction or applied at a later date using an aerosol spray, collects solar radiation.
It converts the radiation into heat and spreads it evenly around the surface, so the melting is not simply confined to areas in direct sunlight.
Scientists say the new method is a completely passive, solar-powered way of combating ice build-up.
According to experts, the material could be used to construct panels to prevent icing on roofs of homes, schools, and other buildings.
Preventing potentially dangerous build-ups of ice usually requires energy-intensive heating systems, or chemical sprays that are environmentally harmful.
The new system, created by researchers from Massachusetts Institute of Technology (MIT), is based on a three-layered material that can be applied to frozen surfaces.
Once applied, it requires no further action or power source, according to the research, which is published in the journal Science Advances.
Since the material can be powered by artificial lighting as well as sunlight, it can be used to de-ice surfaces at night, as well as during the day.
‘Icing is a major problem for aircraft, for wind turbines, powerlines, offshore oil platforms, and many other places,’ said MIT associate professor of mechanical engineering Kripa Varanasi, who authored the new study.
‘The conventional ways of getting around it are de-icing sprays or by heating, but those have issues.’
The usual de-icing sprays for aircraft and other applications use ethylene glycol — a chemical that is extremely environmentally unfriendly.
Airlines don’t like to use active heating, both for cost and safety reasons.
Dr Varanasi and his team found it is not necessary to produce enough heat to melt the bulk of the ice that forms on a given surface.
Instead, all that is needed is for the boundary layer – right where the ice meets the surface – to melt enough to create a thin layer of water.
This then makes the surface slippery enough so any remaining ice will slide off.
The top layer of the three-ply material absorbs sunlight and converts it to heat.
The material the team used is able to absorb 95 per cent of the incident sunlight and loses only 3 per cent to re-radiation.
In principle, the layer could help to prevent frost formation but with two limitations.
The new method is a completely passive, solar-powered way of combating ice build-up and can be used on power lines, researchers say (stock image)
Firstly, it would only work in the areas in direct light — sunlight, or artificial.
Secondly, much of the heat would be lost back into the substrate material – the aeroplane wing or powerline, for example – and would not help with the de-icing.
In order to compensate for this, the team added a thin layer of aluminium — just 400 micrometres thick.
This is heated by the absorber layer above it, which spreads heat out laterally to cover the entire surface.
The material was selected to have ‘thermal response that is fast enough so that the heating takes place faster than the freezing,’ Dr Varanasi added.
Finally, the bottom layer is simply foam insulation. This keeps any heat from being wasted downward and keeps it where it’s needed at the surface.
‘In addition to passive de-icing, the photothermal trap stays at an elevated temperature, thus preventing ice build-up altogether,’ said postdoctoral student Susmita Dash.
The three layers, all made of inexpensive commercially available material, are then bonded together, and can be bonded to the surface that needs to be protected.