Geothermal Energy Making a Hot But Quiet Comeback

Geothermal energy is nothing new, no more so than many of the so-called renewable energies.  Iceland has been powering their nation and heating homes for almost four decades with geothermal energy and heat.  The perception may be that geothermal fields exist only in famously volcanic areas such as Iceland.  But, that is far from true.  The truth is there is significant volcanic activity on almost every continent and within every nation.  And, there are geothermal power plants all over the world producing clean energy to millions of people including in including Africa, Australia, New Zealand, Chile, Russia, the UK and the US, just to name a few.  But, it seems to me that geothermal, as an energy source, suffers from poor branding, that is, it is not as well known as other green energy sources.  But that seems to be changing.

This is due to many factors but the primary reason is the obvious one and the elephant in living room – global warming.  Scientists have been warning people and policy makers for quite some time now but many weren’t listening.  It seems that people are finally listening and, the search for alternative energy sources is in full swing.

There are advantages and disadvantages for almost all energy sources and geothermal is not alone in this.  Hydropower, solar, wind power, bio fuels, tidal and nuclear all have their up sides and down sides, some more than others.  The advantages of geothermal are many: they deliver low cost electricity, produce very low emissions, are unaffected by changing weather, provide a continuous power supply (base load). And, geothermal power plants are scalable, meaning they can produce power for a small town or a large city depending on the size of the geothermal field and generating capacity of the plant.

There are disadvantages of course.  Geothermal power plants deal in very corrosive fluids which require special handling, these power plants do emit low levels of carbon dioxide, sulfur, nitric oxide and geothermal hot water can contain trace amounts of heavy metals such as mercury.  But there are techniques and technologies that exist today that can mitigate most of these issues down to a negligible figure.  There are also concerns that geothermal fields can be depleted, i.e. that the heat is sapped out to a level that makes it very inefficient from a power generating standpoint.  But, the counter-argument is that very careful consideration must be given as to the potential of a field and that the size of the generating plant must not be too large as to sap the reserve.

Furthermore, new technologies exist today that are making it more possible to extract energy efficiently from low temperature fields. I am not an engineer so please excuse my rough description of these technologies.  This new technology is called Kalina and it is an advancement to the binary cycle geothermal plants in that it uses an ammonia and water mixture to produce steam to drive the turbines.  Ammonia is used because it has a much lower boiling point than water.  The Binary cycle type plants, in general produce much less emissions by use of a heat exchanger wherein the hot water from the ground heats a secondary fluid like isobutane, or in the case of Kalina, an ammonia mixture, which is vaporized to drive the turbine.