Geo Thermal Energy – Life Under the Crust

The center of the earth is HOT, very hot! In fact so hot that the center of the earth is molten lava. The heat of the molten lava dissipates as it gets nearer the earth’s surface, which is why ground under our feet feels cool. In the sixteenth century as mining became more common, man realized that the further down you went, the more heat there was in the earth around them. As scientists studied the reason steam rose from water in cold weather and what created this phenomenon, the science of geo thermal energy was born.

Visible evidence of this heat under the surface is found in geysers, volcanoes and hot springs, but what happens is simple. The difference in temperature between deep hotter zones and shallow colder zones generates a conductive flow of heat from the deep hots towards the shallow cooler zones, with a tendency to create uniform conditions. This means that you can create energy with this heat transfer and generate electricity from it. After all, in 33,000 sq ft of the earth’s crust there is more power than 50,000 times the generating capacity of all the fossil fuel in the world combined.

The most common current way of capturing the energy from geothermal sources is to tap into naturally occurring “hydrothermal convection” systems where cooler water seeps into Earth’s crust, is heated up, and then rises to the surface. When heated water is forced to the surface, it is a relatively simple matter to capture that steam and use it to drive electric generators. Geothermal power plants drill their own holes into the rock to more effectively capture the steam.

There are three designs for geothermal power plants, all of which pull hot water and steam from the ground, use it, and then return it as warm water to prolong the life of the heat source. In the simplest design, the steam goes directly through the turbine, then into a condenser where the steam is condensed into water. In a second approach, very hot water is depressurized or “flashed” into steam which can then be used to drive the turbine.

In the third approach, called a binary system, the hot water is passed through a heat exchanger, where it heats a second liquid—such as isobutane—in a closed loop. The isobutane boils at a lower temperature than water, so it is more easily converted into steam to run the turbine.

Geothermal springs can also be used directly for heating purposes. Hot spring water is used to heat greenhouses, to dry out fish and de-ice roads, for improving oil recovery, and to heat fish farms and spas. In Klamath Falls, Oregon, and Boise, Idaho, geothermal water has been used to heat homes and buildings for more than a century. On the east coast, the town of Warm Springs, Virginia obtains heat directly from spring water as well, using springs to heat one of the local resorts.

In Iceland, virtually every building in the country is heated with hot spring water. In fact, Iceland gets more than 50 percent of its energy from geothermal sources.  In Reykjavik, for example, hot water is piped in from 25 kilometers away, and residents use it for heating and for hot tap water.

This principle is so reliable it can be practised on a small scale at home. A Geo thermal heat exchange systems capitalize on the temperature under the earth’s crust and turn it into cheap heat for your home over winter, and as a bonus, because of the constant temperature underground, it keeps cools your home in summer too.

Geo thermal is an excellent source of renewable energy and one that will grow as more people invest in it. Like many other green practices, the investment may be larger than standard energy sources, but once that investment is made, the returns soon pay for the outlay and continue to make savings. Renewable energy doesn’t come much easier than this! Vote with your heater! Go geothermal.


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