Deicing
De-icing can be accomplished by mechanical methods (scraping, pushing); through the application of heat; by use of dry or liquid chemicals designed to lower the freezing point of water (various salts or brines, alcohols, glycols); or by a combination of these different techniques.
These compounds are often generated as byproducts of agricultural operations such as sugar beet refining or the distillation process that produces ethanol.
[3][4] Other organic compounds are wood ash and a de-icing salt called calcium magnesium acetate made from roadside grass or even kitchen waste.
[5] Additionally, mixing common rock salt with some of the organic compounds and magnesium chloride results in spreadable materials that are both effective to much colder temperatures (−34 °C (−29 °F)) as well as at lower overall rates of spreading per unit area.
[6] Several of these new compounds release very small amounts of gases into the air, which are known to be able to cause irritation of the throat and the respiratory tract in humans and animals.
[7] This automated form of renewable energy collection, storage and delivery avoids the environmental issues of using chemical contaminants.
It was suggested in 2012 that superhydrophobic surfaces capable of repelling water can also be used to prevent ice accumulation leading to icephobicity.
[9] Trains and rail switches in Arctic regions can have significant problems with snow and ice build up.
Ice protection systems typically use one or more of the following approaches: De-icing operations for airport pavement (runways, taxiways, aprons, taxiway bridges) may involve several types of liquid and solid chemical products, including propylene glycol, ethylene glycol and other organic compounds.
However, urea is a significant pollutant in waterways and wildlife, as it degrades to ammonia after application, and it has largely been phased out at U.S. airports.
Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol.
