After talking in a previous post about the very promising future of geothermal energy, let's look in more detail how an ORC plant designed by Turboden can make this renewable energy much more efficient, when used to generate electric power.
The process starts with the extraction of geothermal water, at a temperature of about 140°C. Water is then filtered, further heated, and sent to a heat exchanger. The thermal energy is then transferred to the thermal fluid, which evaporates and moves a turbine to produce electric power.
So far, it's the ORC process as we know it, but what happens to water once it gets to the end of the ORC loop?
If we compare it to eolic energy, geothermal power has a quality that cannot be ignored: in order to be truly renewable and with no impact on the environment, water extracted from the underground has to come back to its original place.
The reason is indeed very simple: without this step, water from underground wells would become part of its normal cycle between the earth and the sky, contributing, marginally but significantly, to raising the level of the oceans.