Well the weather outside is frightful... and so is the transport situation. But roads, rail, runways, and even all manner of Nature's creatures would be far worse off were it not for antifreeze
“It’s snowing!” – The cry provokes a mixture of feelings in most of us who are over 16 years old. It can be beautiful, romantic and fun but once a year is quite fun enough, thank you very much, because work and the shopping still need to be done.
Children and dogs deal with it by running and rolling about until chilled to the bone before dripping all over the kitchen floor and eating like a horse for the rest of the day; cats just curl up in their favourite warm spot indoors.
The wildlife, on the other hand, has to migrate, hibernate or endure the freezing temperatures. Birds fluff up their feathers, insects surround themselves with dry leaf litter and worms burrow deeper underground. However, these defences are sufficient only for moderately cold weather. Cold though we think Britain is this winter, there are parts of Siberia and Alaska where the temperatures regularly reach minus 50 or 60 deg C.
In such places, cold-blooded animals have a much better chance of survival if they can avoid freezing – though the odd one or two have developed an ability to revive themselves after being frozen stiff. Others literally make their own antifreeze.
Antifreeze is anything that lowers (“depresses”) the freezing point of water. This is, in theory, almost anything; the freezing point of water is dependent on the amount of other molecules dissolved in it, and those molecules’ freezing points. Ice is a remarkable structure, made by strong hydrogen bonds between water molecules. Adding any antifreeze additive means fewer of these bonds can form, and ice crystals can’t form until the temperature gets even lower. This is how it works both in man-made products and in nature, too.
Proteins in the blood plasma of Antarctic fish have been known for some decades to act as antifreeze. More recently, scientists have discovered that the snow flea, found in many parts of the world including most of Britain, employs different types of protein to prevent ice crystals growing. Both the fire coloured beetle and spruce budworm caterpillar of North America have evolved to use other proteins as antifreeze. The list goes on. There’s more on natural antifreeze here.
As so many different types of antifreeze-making insects have been discovered in North America, I assume that there are many other species around the world with antifreeze mechanisms that have not yet been discovered.
Insects make human use of antifreeze appear crude and basic. But without the salt and grit combination on our roads and pavements, traffic would soon come to a standstill and footpaths would remain treacherous in the winter ice and snow. Salt lowers the freezing point of water but it takes so long to work when temperatures are very low that it is not really effective much below minus 10 deg C.
Calcium chloride is a better option in very cold conditions, but it needs to be kept particularly dry before use to stop it going all mushy. Various chemicals are used for different conditions, though like common salt they have drawbacks: corroding metal, attacking concrete or harming vegetation, for example.
In our bid to continue as normal and ‘overcome’ the forces of nature, we seem to forget that there is a price to pay for having ice free roads. I am glad that oil and food distribution networks are kept open but we really should stop whinging about ungritted side roads. Shovels work very well and provide free communal activity.
Airports have to maintain ice-free runways. Road grit cannot be used because it would enter engines and cause damage so a liquid de-icer is used instead. However, the actual aircraft have to be free of ice as well before takeoff. If the wings are not smooth, air flow over them is disrupted, they don’t generate as much lift and the aircraft can crash. Pieces of ice can also break off the aircraft once it is moving and be sucked into engines or hit propellers.
Airline workers spray onto the aircraft a deicing fluid based on propylene glycol, similar to antifreeze for car engines, to remove any ice. They then spray on a thick, gloopy version of antifreeze to reduce the formation of more ice before the aircraft can take off. This thick anti-icer becomes thin and runs off when the aeroplane accelerates and air moves over it quickly. The wings regain their smooth contours, enabling a safe takeoff for the passengers. Antifreeze is reclaimed and recycled by responsible airports. Chemical & Engineering News has more on deicing aircraft.
Snow and ice disrupt travel but without the deicing and anti-icing chemicals we would have a lot more trouble. Even so, nature can still teach us a trick or two. Antifreeze proteins could be used to preserve organs and tissues for transplant surgery, prevent frostbite and protect crops from frost damage. We could enjoy smooth ice cream for its entire shelf life – however many times we warm it enough to dig out chunks with a spoon before putting it back in the freezer. You might not think it now but come the summer, we’ll be glad for some frozen food as we swelter in a heat wave. That’s when ice is nice. blog comments powered by