Clean Heat with Geothermal Energy
Because of the world's dependence on oil and coal, many governments have been looking to alternative forms of energy to supply us with electricity into the twenty-first century and beyond, which is still said to become the start of a golden age of prosperity for all. Accounting for a little less than one percent of total electrical generation right now, geothermal energy could soon become a major player in the world of energy, accounting for possibly ten percent or more of generated electricity globally. However, it does carry with it some concerns about possible global side effects.
Potential Use
Geothermal energy is estimated to be able to provide enough electricity for all of the world's needs for several millenia at least. As with solar and wind technologies, geothermal technology is vastly improving in terms of efficiency and cost, and eventually it's expected to provide at least fifteen percent of total energy needs worldwide as it's weighed against other alternatives in terms of efficiency and cost in a given location. Iceland, for example, generates upwards of two hundred megawatts of electricity using geothermal energy at the moment. Sunnier areas might opt for solar or nuclear energy for their energy needs. In total, geothermal energy is best used to complement other forms of electrical output to achieve the most stable and efficient network of power generation possible.
Environmental Risks
Geothermal energy plants can adversely affect the environment. The plants themselves don't generate pollution (although some emit trace amounts of sulfur and other chemicals, although nothing alarming by any account), but by injecting hot water into the ground, they can destabilize the land. Also, by overusing heat reserves in the ground, plants can deplete the Earth's large heat reserves, but proper use would prevent this from becoming a problem.
Geothermal energy plants use heat stored beneath the ground to generate electricity in several ways, generally including steam to turn turbines to generate electricity. With proper use, they can use the Earth's heat reserves theoretically indefinitely as long as they don't use too much in too short a time, which would require the Earth's mantle to replenish the heat over the course of years or decades. However, they can destabilize the ground by injecting water into ground that was previously dry, weakening the ground's potential much like overdrawing from a well can limit a ground's water capacity. If used properly, geothermal energy will provide us with all the energy we will ever need.
