Hanson’s first castle started in 2007 and grew to about 16 feet with two levels. In the 2008-2009 season, it transformed into a crazy monolith with sharp ice points jutting out from it. The 2009-2010 version included spires and turrets and finally this year the giant ice castle is a tall, long wall measuring 65 feet at its height and 85 feet long with multiple tiers of ice layers. This year’s project began in November when Hanson set the poles and started growing the initial layers the first week of December. Now that it’s February, the ice castle will start to melt and eventually disintegrate around the end of April.
These amazing sculptures are made possible because of Hanson’s geothermal heating system used to heat his home. As you will recall, a geothermal heat pump works like a reverse refrigerator taking heat from one source and rejecting cold into another. In Hanson’s case, his system takes ground water at 47 degrees to preheat his home and then rejects the water at 37 degrees into the pond near his home. During the winter, he takes this super cold, but not frozen, water and uses it to form his ice castles.
Cold water is constantly dripped through lines (so it doesn’t freeze) and sprayed through special nozzles onto the frames Hanson has built. The sprayed water freezes in place and over a couple of months, the ice castle has grown to its ultimate height of 65 feet. Hanson also created a specialized computer program to control the sprayers, which takes input from a weather station on his roof to adjust for temperature and air direction. Once the water is sprayed, it takes on a life of its own in the ice crystals and shapes it forms.