Before a geothermal energy plant can be built, a land survey needs to be conducted to ascertain where sources of geothermal energy are located. This can be a slow process, sometimes taking several years to complete, making this a slow source of energy to harness.
Geothermal energy is obtained from hot rocks deep below the earth's surface. However, geothermal energy is present in only a limited number of places in the world. In these places, it is often hard to access, because the rock above is difficult to drill through or it is in an inaccessible site, such as below a settlement or in a protected area of natural beauty.
Geothermal energy sources are often close to volcanoes. This makes building a geothermal energy plant a risky undertaking, as volcanic eruptions and earthquakes can destroy years of hard work. It can be difficult to find a company willing to fund a plant in these areas.
As the earth's core will always produce heat, geothermal energy is a renewable (non-exhaustible) resource, However, despite its sustainability, using it as an energy source has some potential negative environmental side effects. Among them is the potential for harmful gases, such as hydrogen sulfide, and hazardous materials, including mercury, ammonia and arsenic, to rise to the surface during the extraction stage. Arsenic is harmful to human health and can ultimately cause death. Disposing of these materials is challenging and can lead to environmental degradation.
Once the well is drilled, there is no guarantee as to the life span or usability of energy that can be secured, either due the remoteness of the location or deficiencies in the source or the conversion system. For example, a source that has been extracting steam and converting it into power for years can, without warning, stop production. Typically, this occurs after a 10-year period.