Our central heating system allows us to efficiently heat most of our campus all at once from renewable sources. The system consists of a 20,000-gallon insulated water tank with copper heat exchange coils that allow us to move large amounts of heat in and out of the water. This tank acts as a giant thermal energy storage battery, and we use that thermal energy to provide heat and hot water for the Hilltop Cabins, Cedar Lodge, the Activity Center, the gym, and the maintenance garage. We put heat into the tank from the following three sources.
Gasification Boilers
During the winter, our primary sources of heat are three large wood gasification boilers, which accept one-meter long logs. By coupling wood boilers with a thermal storage tank, we are able to keep the boilers burning hot and clean, with no damping, and fewer particulate emissions. We source the wood locally from our own land. In one year, we burn 40-50 cords of firewood to heat all of these buildings. Although burning wood does emit CO2, it is CO2 that is part of the modern carbon cycle, not ancient fossil carbon. We are also confident that our local harvesting techniques allow us to burn less carbon than our forest is absorbing each year. We feel that on this scale, biomass can be a better alternative than fossil fuels.
Waste Heat
The second heat source is waste heat from our snowmaking system. Unfortunately, our snowmaking system requires a diesel generator to create 3-phase power which is otherwise unavailable to us. This generator isn’t the most efficient system for creating 3-phase power, with only one third of the total power produced able to be used for snowmaking. Traditionally, the other two-thirds are lost as waste heat but we use a heat recovery system to capture most of this waste heat and pump it into our hot water storage tank, which means that making snow also heats our buildings. Since we usually make snow when it’v very cold out, those are also times when we need lots of heat.
Solar
Finally, heat is added to the storage tank from an array of solar hot water collectors on the roof of Cedar Lodge. Our solar system is a simple drain-back system that provides enough heat in the summer months to largely eliminate the need for burning wood during that time. During the summer when we're not space-heating, the tank is maintained at a lower temperature, and water-to-water heat pumps are used as needed to produce hotter tap water.