Coffee time challenge: A cold problem

For stuff that is so light and fluffy, snow is remarkably heavy to move in bulk. While weight of snow is nowhere near as big a problem in the UK as it is in Scandinavia or Russia, the high rainfall for which Britain is famous means that when it does snow, there is lots of it. Many parts of the World have long winter seasons, eight months in Northern parts of the USA and Canada, which has allowed much thought to be devoted to the best methods of clearing snow both on a large scale and on a smaller domestic scale. The Challenge Our challenge this month, therefore, is come up with the best possible aid to removing snow from one's drive and the pavement in front of one's house. One solution favoured in the US is to use snow blowers, but this is hardly an eco-friendly concept, and in a country with relatively small gardens, would be likely to succeed in blowing snow from one drive into somebody else's. Melting snow away wastes even more energy and is even less eco-friendly. Salt forms a eutectic with water ice so that the resulting mixture is liquid, but an awful lot of salt would have been required to deal with the snow that fell in late November and early December 2010, leading to possible pollution problems. When the Romans sought to destroy the economy of Carthage, they ploughed the fields with salt, and salt from evaporated irrigation water is a major cause of desertification in the Middle East. The solution offered in our February edition solves the problem elegantly and at low cost in a most elegant way. Our pre-industrial age ancestors could have invented it except they didn't and the idea is sufficiently novel to be protected by patents. Once you see it, you may consider it obvious. See if you can come up with anything better.