How long has geothermal technology been around?

Archaeological evidence shows that over 10,000 years ago the North American Paleo-Indians settled near hot springs and were the first humans to use geothermal energy. Since many people live in areas without those hot springs, another way of harnessing the earth’s renewable energy was needed. So, in 1948 Professor Carl Nielsen of Ohio State University developed the first groundwater heat pump, for use at his residence. While modern advances in technology have increased the efficiency of these machines, the concept remains the same. Today, 85,000 geothermal heat pumps are installed annually across the United States and geothermal energy is considered an important step toward energy efficiency and the reduction of global warming.