Geothermal energy

Geothermal energy harnesses the heat energy present underneath the surface of the ground in two ways. In areas of past or present volcanic activity, pockets of hot magma exist close to the surface. In these areas underground reservoirs of hot water form. When holes are drilled in to a reservoir, steam or hot water is collected, purified and is used to drive turbines, which power electric generators. Additionally, in areas where no volcanic activity is present, ground source heat pumps can remove the heat that is present below the frost line by using heat gathering loops buried in the ground. This heat is exchanged in a form of reverse air conditioning to be used for space heating. Ground source heat pumps can be efficiently used in all but the most severe cold climates.

Areas where high levels of geothermal energy exist such as Iceland, California and Hawaii, can be exploited to generate electricity for other area instead of burning fossil fuels. Once a geothermal electrical generation plant is on line, that facility produces no emissions. Geothermal plants are most often placed in areas of little development and their construction have little environmental impact.

Geothermal of ground source heat pumps can be used in areas of medium or low geothermal energy. A ground source heat pump uses the ground below the frost line to either heat or cool a water loop. This water loop is then introduced into a refrigeration cycle. Because the ground stays at a uniform temperature, between 45 to 70 degrees F depending on the latitude, systems run much more efficiently than air source heat pumps or conventional HVAC equipment. Most estimates range between 40-50 percent savings on heating and cooling costs.

This translates to reduced use of electricity and or fossil fuels to heat or cool a building. For more information read Geothermal article at the Alternative Energy Wiki

Many nations, states and private entities are scrambling to secure their respective energy futures in the face of growing oil prices, coupled with growing demand. A long overdue paradigm shift is emerging, a significant move towards renewable energy development. Many are taking a fresh look at geothermal energy.

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, 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.

The bottom line is I believe we are going to be hearing a lot more renewable energy development in the coming years and that geothermal energy and geothermal power plants will be the hot technology. The potential is vast, the technology exists and the time is now.