Q&A.; Battling the Ice
Q. Hey there — been really enjoying Treehugger over the last few months. I ended up finding a number of great holiday gifts based on recommendations you've made. Sustainability is in effect, son!
Anyway, I'm writing because I was wondering what the most eco-friendly (yet effective) alternative to store-bought salt or kitty litter is for use on icy sidewalks. The Magic Salt you mentioned sounds great, but I'm thinking more on a consumer level. Any suggestions? Hurry up, before the first big snowstorm hits! (Though at this rate, in VA, I doubt we'll get any snow this year.) Ryan.A. Thanks for the question, Ryan. We'd love to give you a simple answer, so we will: shoveling. Clearing away snow before ice has the chance to form is the only method that doesn't add anything potentially dodgy to the environment, and on top of that it's good exercise. Just steer clear of the gas-powered snowblower!
Of course, it's a bit trickier than that. You can shovel your little heart out, but it will make no difference when freezing rain comes. Try breaking up ice that's formed with a flat hoe. Though depending on the size of your sidewalk and driveway, you could be hacking up ice forever. So on to the not-so-simple answer....
Home remedies like sand, ash, and kitty litter are an affordable option, but they're not terribly enviro-friendly. Both do nothing to melt ice and instead only add traction on top of it. Depending on your needs, that might be enough. Conscious Choice says that sand is the best for traction, but what's the greenest? They warn that ash and cat litter (a clay-based product) can adversely affect vegetation and get into water systems. Sand seems like the better choice since it's already found in nature, but it can clog up sewers and lower air quality in areas that use a lot of it. Most of the pollution, though, comes from airborne microparticles created when cars pulverize the grains of sand—if you're just covering a low-traffic sidewalk, that's not so much of a concern.
Rock salt (sodium chloride) does have melting properties. It's cheap and effective (though not at temperatures much lower than 15 or 20 degrees Fahrenheit), but it's also corrosive to concrete and cars. And it can increase salinity in local bodies of water, causing long-term damage. If run-off from the sidewalk in question goes into a pond, lake, or river, bad news.
Fertilizers like potassium chloride and urea are best avoided for melting ice near vegetation, since the high concentration needed can burn plants rather than fertilize them. Some experts think calcium chloride is the best choice among chemical deicers, since it needs on average only 3 oz. per square yard while rock salt and urea need 8 oz. Magnesium chloride is similar, but only half of the substance actively deices so you'll need more of it. Bare Ground Systems sells a magnesium chloride deicer made from agricultural by-products that it claims is environmentally safe and biodegradable (the shaker jug mixes it with salt, though). Various blends are also available from Scotwood Industries, who say that calcium chloride "is as safe [for the environment] as every other ice melter on the market." As we've seen, the other deicers aren't very green either, so beware of misleading marketing (even though calcium chloride may actually be a better option).
A University of Maryland chart compares just how safe the various ice melters are, listing whether each damages concrete, metal, or plants. The clear winner, with a "no" in both the harm columns, is calcium magnesium acetate. Why haven't we mentioned it? It's expensive and, like the Magic Salt that prompted this question, not readily available for home use. Nor is it a huge help for your sidewalk: instead of melting, it turns ice the consistency of oatmeal—a bit messy for foot traffic. There was a lot of talk around the turn of the century (20th to 21st, that is) about CMA that was even more eco-friendly. Though it's normally made from petroleum, corn can be used instead. The US DOT thought production costs could be cut by 30% if whey from commercial cheese-making was used. Tons of otherwise useless industrial waste would have found a purpose, too. But the buzz seems to drop off the radar circa 2000, so fill us in if you know anything.
Bottom line: back to the simple answer. Do it manually when possible. If you've got to use deicer, keep the amounts minimal—follow the manufacturer's instructions, or use a bit less. Make sure any product you choose is compatible with the temperatures you're facing. Best of luck for the winter, Ryan! [by KK]
The great article at Conscious Choice that we mentioned above has loads of information if you want to know more.