Geothermal energy does not produce any CO2, or any chemical left over's. From this point of view it is environmental friendly.

Though it has some environmental impact:
The pumping of water in geothermal plants may affect the environment:

- Hot springs in the area may dry up

- Geysers, which is a very rare natural phenomenon, may alter (e.g. the frequency it appears, or the height in which it goes) or even vanished.  

- The water used in geothermal factories contains dissolved gases and solids, which discharged into the atmosphere. Which substances are contained in the water, and in which quantity varies from one hot spring to another. Hydrogen sulfur H2S is the biggest problem due to its toxicity and odor. Different ways are used in order to remove it from the water. Other dissolved substances such as carbon dioxide C2O and methane CH4 are also considered a problem because they contribute to global warming. Gases such ammonia, radon (radioactive) and the boron should also be treated properly.

- The noise at the plant is a serious problem for the workers. Installations of filters that reduce it, is a necessity.

- The gases are released into the atmosphere at high temperature. This may affect the climate at the local level e.g. fog, or a small rise in the temperature. The warm water that is not used is discharged into rivers or lakes. This leads to a raise in the temperature of the water and therefore to changes in the ecosystem.

    geyser (Iceland)