Getting to Know Geothermal Based Power Plants

 Indonesia has a very large geothermal potential, which is mostly underdeveloped due to several obstacles.  This has not deterred the government’s attempt in maximizing  available potentials by addressing these obstacles.

With the large amount of available potentials, Indonesia will not only able to fill its electricity demand, but also has the capability to export geothermal-sourced electricity.  Indonesia’s current geothermal potential equals to 28 GW, of which only 1189 MW (4%) has been harnessed.

Geothermal energy is centralized below the earth’s outer shell, where each 100m in depth, the temperature of molten rocks increases 30ºC.  If we calculate a surface temperature of 270ºC, at a depth of 100, this will increase to 300º.  Going deeper, at a depth of 1 km, the rock and mud temperature will be 600ºC, reaching 1200ºC at a depth of 2 km.

The are some cases where water is located near these heated rocks, in temperatures of 1480ºC.  This water will not turn into steam because of a lack of air, but due to the large pressure involved. will exit the surface through cracks in the earth’s surface, resulting in what we call a hot spring.

Whenever this heated water mixes with air due to fractures, it will form a steam, which exits along with the water itself.  This heated water and steam is what powers the geothermal power plant to produce electricity.

Geothermal reservoir is commonly classified into two categories, those with low temperature (< 1500ºC) and high temperature (>1500ºC).  For power generation, it is best to use the high temperature reservoir, but with advancing technologies, it is now possible to use low temperature reservoirs, given that it is above 500ºC.

Geothermal power plants is able to operate at a relatively low temperature of 50-2500ºC, compared with nuclear power plants which operates at 5500ºC, giving it one major advantage.  One other benefit of geothermal power plants is that it is the cleanest of all power plant types, not to mention the safest.