The chemicals we put on our roads and sidewalks to melt ice and snow all work in the same way; they depress the freezing point of water by adding dissolved particles. Salt for example adds one sodium and one chloride ion for every molecule of salt added to the water. The more salt added to the water the lower the freezing point will be, until no more salt will dissolve in the water. In the lab the freezing point of salted water can be lowered to -9°F; on the sidewalk under less than ideal conditions it can be lowered to 15°F. This is why that salt becomes ineffective on the roads in really cold conditions.
Salt is a highly corrosive substance; it damages concrete and is toxic to vegetation. The runoff from the roads gets into streams and wells and can cause problems for wildlife and homeowner alike. Are there organic alternatives that might work without the problems caused by salt and other chemicals? At the February meeting Ether introduced us to urea. She says she put it down before a snow storm and the ice “floated” off the part of the sidewalk where the Urea was spread.
Urea is excreted by the kidneys as a waste product in urine or it can be synthesized. Most of it is used in fertilizer. This makes it ideal around plants as it isn’t toxic and provides a source of nitrogen. Urea is essentially environmentally safe. It is still somewhat corrosive to metals as most of the urea sold is an agricultural grade. For this reason it is not used around aircraft for deicing and runways. Pure urea however is not corrosive.
There are a number of problems with using urea to melt snow and ice. One is that it is very slow acting. A second consideration is the form of the product. Most urea is manufactured in a prilled form which is a sphere created from a melted liquid. This shape makes it easier for the urea to roll on the ice or to be blown away before it does its job. The rounded form shape allows for less surface contact greatly reducing its effectiveness. Urea is also prone to refreezing and is only effective down to 15°F.
These drawbacks probably apply more to commercial and road use than they do to the average gardener, who may just be looking for something that will melt the ice without contaminating the soil. Urea is readily available for home use, although according to Esther, more expensive than salt.
Another method of melting ice was brought to our attention by Sharon. It is even more intriguing. This method mixes salt with the juice that is left after the sugar has been removed from processed sugar beets. This mixture, called Geo Melt (80 percent saltwater, 5 percent calcium chloride and 15 percent beet juice), is more effective in melting snow and ice than plain salt when temperatures fall below 0º F. It also reduces the corrosive qualities of the salt and allows much less of the environment damaging salt to be used while achieve the same results It reportedly melts ice at temperatures of -20º .
The beet by-product is also sticky, which helps the GeoMelt stay on the roads. Beloit, a city in Wisconsin, sprays the beet juice on the streets before the storm and then uses salt. The adhering quality of the beet juice keeps the salt from being flung to the side of the road by traffic or wind.
On the con side, under some weather conditions, the mixture does not seem to be effective. It is also expensive; with the beet juice priced at $1.80 a gallon vs. 4cents a gallon for brine. The 80/20 ratio may have to be raised to a 50/50 ratio under certain road conditions according to the Beloit testing. Jim O’Reilly, the eastern Michigan region sales consultant for Road Solutions Inc., however says that mixing 6 gallons of beet juice with a ton of road salt is effective to -25º. He says that plow truck drivers have told him that plowing on roads treated with this product is like plowing on Teflon. Obviously all of the data is not yet in.
GeoMelt is not yet available to the retail market for home use. It is only being used in a few communities, and on hospital and university grounds. The product is produced in Michigan and is being tested primarily in that area.