mandag 7. februar 2011
When snow gets a function
The snowdeposit on Åsland was established in autumn 2006, with paving and drainage, and is the only landfill Samferdselsetaten have in Oslo. When the landfill is full, its been dumped about 250,000 cubic meters of snow here, which is estimated to be about 12 000 truck loads full of snow.
Snow removed from the roads is significantly contaminated by road salt, metals and organic pollutants, but if the landfills are designed appropriately it can reduce the spread of pollutants. The main sources of the contamination is wear of the road, tires, brakes and exhaust. Previously, large amounts of the snow was dumped into the harbor every winter, but because of unwanted litter and growth in the sediments, this was stopped, and the landfill was established instead. The snow that’s been cleared from the streets of the iner city includes both garbage, particles such as sand and gravel, various salts, oil, and not least significant amounts of pollutants. Norwegian Institute for Water Research (NIVA) has estimated that winter 93/94 the snow dumped in the sea added Bispevika (the sea) in Oslo about 1000 tonnes of particulates, 60 kg zinc, 29 kg lead, 20 kg copper, 20 kg chromium, 8 kg PAH and 7.5 tonnes of oil. The snow also contained in the order of 50-190g of the highly hazardous environmental exposure to PCBs.
The massive amount of snow doesn’t melt untill september and may be looked upon as a man made glacier. The transportation of this large amount of snow contributes to a lot of polution from the trucks and also an extra pressure on the road system. In an interlocked local system are there any other ways to solve this?
The content of pollutants in the melted water means it must pass through a treatment plant before it can be released. In the current energy debate it is an important step in making energy use more environmentally friendly. It is important not to forget the cooling demand in this debate. Many commercial buildings and office space has a great need for cooling in summer. At Grønland, a lot of the buildings are solely commercial buildings that’s dependent on heatreducing airconditioning systems, whats the possibillity for the establishment of local snowdeposits which can be connected with the established building mass. A project in Sweden, the hospital of Sundsvall have established such a system; The hospital has a large need for cooling in summer. The air outside are often of 25 degrees, so it is necessary to lower the temperature. This requires a lot of energy in such a large building. This unique project aims to reduce energy consumption, save money and stop all use of freon in the cooling system.
The snow collected from clearing the areas around the hospital, app. 30,000 m3 of snow will be stored on a 7,000 m2 large area. In late April, when theres enough snow, it is covered by wood chips or sawdust. The snow will then be placed under the insulating layer, and slowly begin to melt in May.
The melted water then has a temperature of approx. 1 plus degree and this is pumped through a heat exchanger. Air pumped into the heat exchanger will be reduced to around 20 degrees. After the melted water has passed through the heat exchanger it is sent back to the snowdeposit with a temperature of approx. 15 ° C. The water helps to melt the new snow, which is then pumped back to the hospital again. This cycle continues until all snow has melted.