Geo-Thermal Energy

While there is a great deal of energy coming from outside of the earth, such as solar energy, there is still a great deal of energy beneath us, buried deep in the Earth's crust. There are several ways to harness these underground heat sources, let's explore them.

Tapping Into the Crust: Geothermal Heat Pumps

The upper 10 feet of the Earth's surface does not change temperature very often. The average temperature hovers around 50°F-60°F. By inserting heat-transfer elements into
the ground, and using a pump to bring that heat energy up, homes in the winter time can be heated. During the summer, the system goes in reverse, transferring the hot air in the house, into the cool ground. Many users of these systems say they are quiet, and provide satisfaction rates of over 90%. While these system do require electricity themselves to run the pumps, this pales in comparison to the electricity used in conventional heaters.

Electricity Strait from the spring: Geothermal Power Plants

One of the oldest forms of electricity generation, ground steam used to turn turbines
(hydrothermal energy) has been used as far back as 1904 in Italy. Naturally occurring steam from springs is tapped and driven through a turbine. This turbine creates the electricity used for homes. This is called Dry Steam Power.

Another form of hydrothermal energy is called Flash Steam. Geysers that contain fluids above 360°F can be tapped just like Dry Steam Power Plants, but the high-pressure vapors are injected into a "flash tank" which is kept at a much lower pressure. The unequal pressures cause the heated fluid to "flash" which will turn a turbine. These "Flash Steam Power Turbines" are more efficient than Dry Steam Power Turbines because any unused fluid can be held in another tank and flashed again.

A third form of geo-thermal energy is called Binary-Cycle. This system employs two closed-circuit systems. The first pumps the hydrothermal fluids up from the ground and into a heat exchanger. The second system pumps another fluid around a closed loop. This fluid in the second system has a much lower boiling point than the geothermal fluid. When the second fluid gets to the heat exchanger, it flashes into vapor and is used to turn a turbine. This system is highly efficient because there are no lost liquids because they are closed circuits. This will eventually be the standard geothermal power plant.