Renewable Resources vs. Nonrenewable Resources
How Geothermal Energy is Produced
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 (dry rock conversion). 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 in a closed loop. The liquid can boil at a lower temperature than water, so it is more easily converted into steam to run the turbine.
Environmental Advantages and Disadvantages of Geothermal Energy
- Geothermal energy is not subject to weather fluctuations or climate changes: it's always on.
- Geothermal plants emit little to no CO2, smoke or steam.
- Geothermal plants are quiet, limiting noise pollution as well as environmental pollution.
- Geothermal energy plants efficiently use natural heat resources as the source of their power and can re-use the small amount of water they pump throughout the system.
- Geothermal energy plants can readily blend into their surroundings, and sit comfortably alongside agricultural environments.
- Is quite cost effective due to its lack of use of fossil fuels.
- Geothermal energy can deplete geothermal resources (such as water, gas and steam) faster than it can replenish them.
- Geothermal energy can cause damage to natural geothermal features.
- Extracting geothermal fluids can reduce the pressure in underground reservoirs and cause the land to sink.
- Geothermal fluids contain heavy metals due to underground exposure, and can affect drinking water and aquatic life if exposed.
- Geothermal fluids contain dissolved gases which are released into the atmosphere, potentially causing pockets of toxic gas.
- Geothermal locations are hard to locate and harness.
- Geothermal energy is not easy to transport, so is only truly effective in surrounding areas.