In this video segment from Las Vegas PBS, visit a construction site where a geothermal heat pump system is being installed to provide a new building with an energy-efficient way to meet its heating and cooling needs. Geothermal energy systems like this one circulate water through two pipes -- one a supply line to the building, and the other a return line from the building. Depending on the season, the water delivers heat to the building to warm it or removes heat from the building to cool it. Geothermal systems replace traditional heating and air conditioning systems that require considerably more fossil fuel to run.