Disadvantages of Geothermal power
As one kind of alternative energy, geothermal power has many advantages such as requires no fuel, and is therefore virtually emissions free and insusceptible to fluctuations in fuel cost. Read this articles for more advantages and details of geothermal power. There are a few disadvantages of geothermal power.
From the perspective of engineering, the geothermal fluid is corrosive and, worse, is at a low temperature, compared to steam from boilers. And by the laws of thermodynamics this low temperature of the geothermal fluid limits the efficiency of heat engines in extracting useful energy during the generation of electricity. Much of the heat energy is lost, unless there is also a local use for low-temperature heat, such as greenhouses, timber mills, and district heating.
However, since this geothermal energy is almost free once the plant is established, the efficiency of geothermal energy of the system is not as significant as for a coal or other powered plant.
Although geothermal power is a clean energy compared to coal and oil, there are several environmental concerns behind geothermal energy.
Construction of the power plants for geothermal power can adversely affect land stability in the surrounding region. This is mainly a concern with Enhanced Geothermal Systems, where water is injected into hot dry rock where no water was before. Dry steam and flash steam power plants also emit low levels of carbon dioxide, nitric oxide, and sulphur, although at roughly 5% of the levels emitted by fossil fuel power plants.
However, geothermal energy plants can be built with emissions-controlling systems that can inject these substances back into the earth, thereby reducing carbon emissions to less than 0.1% of those from fossil fuel power plants. Hot water from geothermal sources will contain trace amounts of dangerous elements such as mercury, arsenic, and antimony which, if disposed of into rivers, can render their water unsafe to drink.
Although geothermal power sites are capable of providing heat for many decades, locations may eventually cool down.
For instance, the world's second-oldest geothermal generator at Wairakei has reduced production. It is likely that locations like these were designed too large for the site, since there is only so much energy that can be stored and replenished in a given volume of earth. If left alone, but, these places should recover their lost heat, as the Earth's mantle and core have vast heat reserves.
Geothermal and biomass are the only two renewable resources which must be carefully managed in order to avoid local depletion. An assessment of the total potential for electricity production from the high-temperature geothermal fields in Iceland gives a value of about 1500 TWh (total) or 15 TWh per year over a 100 year period. And the electricity production capacity from geothermal fields is now only 1.3 TWh per year.