Geothermal+Energy


 * ​Geothermal Energy**

Basic Information and Source of Energy
= = The term geothermal derives from the Greek //geo// (meaning earth) and //therine// (meaning heat), which is logical, since geothermal energy harnesses the heat of the Earth. Geothermal energy finds its energy from the decay of radioactive particles deep in the Earth's core. Temperatures in the core reach 5000ºC and cause the rock in the mantle region of the core to melt, producing magma (the molten form of the lava that erupts from volcanoes) that becomes superheated and heats the surrounding rock and water. This heat energy is then harnessed by people digging deep wells and bringing the heated water or steam to the surface. Geothermal reservoirs, which are naturally-occuring "hotspots", are found deep beneath the earth, and usually show no visible sign of their presence on the surface. Therefore, the heat energy must arrive at the surface somehow, which it does through volcanoes, fumaroles (site of volcanic gas release), hot springs and geysers. Most of the world's geothermal reservoirs are concentrated around the Pacific Ocean, in an area called the "Ring of Fire". Although it is difficult to determine where geothermal reservoirs exist without actual exploration, research has allowed certain technologies to be developed which significantly aid in the finding and characterizing of hotspots.

Classes of Geothermal Energy
== Geothermal energy sources can be grouped into three classes. Direct usage involves heated water from below the Earth's surface being pumped up directly into buildings for use in heat exchange systems (systems that allow for the efficient transmission of heat energy from one medium to another ). The second involves the steam produced by the heating of water to turn a turbine when sufficient pressure builds. The final grouping of geothermal energy is called dry steam. This is when water not normally found near the geothermal reservoir is exposed to the superheated rocks and evaporates into steam, which can them be used similarly to turn a turbine. ==

** Geothermal Power Plants **
media type="youtube" key="rfUQy86ZMpQ" height="303" width="383" align="right" The video shows how electricity is generated at geothermal power plants. Geothermal energy is obtained by harnessing the heat and steam of the Earth in a useful way. In particular, water and steam with a temperature higher than 180°C is commonly used by the power plants for electricity generation. There are three types of geothermal power plants that currently exist. The same basic principle applies to all types. That is that steam has high kinetic energy, as heat is given to liquid particles to increase their kinetic energy and change state. Also the gases used in the process have high pressure as the particles in this state are moving freely and are very spread out, constantly hitting the sides of the container, building pressure. This kinetic energy can be transfered into a type that can do work with the help of a turbine and a generator. The pressure exerted by the highly energy particles of steam, pushes a blade of a turbine. These blades are connected to a shaft that powers an electrical generator. In this way electrical charge is produced from the transformation of the kinetic energy of the particles, into mechanical energy and finally electrical energy. This charge is then directed into a transformer where the voltage is increased.

**1. Dry Steam Plants:**
These plants use steam piped directly from the Earth to turn a generator and create power.

**2. Flash Steam Plants:**
In some places where drilling occurs, hot water (at temperatures of at least 200°C ), is trapped below the Earth in small spaces in porous rocks. This hot water also has very high pressure, until it is channeled into a low pressure chamber above ground. As a result of this dramatic change in pressure, the water "flashes" into steam and the pressure produced from this process also drives the turbine used to create power.

**3. Binary cycle Plants:**
In these power plants, hot water (usually at less than 200ºC) from below the Earth's surface is extracted and used to heat another liquid through a transfer of thermal energy between the two substances. This other fluid, called the "working fluid" has a lower boiling point then water to it can vaporize more readily with less heat. The pressure produced by the change of state is used to drive a turbine and create energy. This system is entitled a binary system as it contains two closed loops (the water and the working fluid). These loops are continous; as soon as the liquid is used, it is cooled and returned to the Earth where it can be harnessed again. As a result, this system produces no emissions or substantial byproducts.

Geothermal Heat Pumps
Geothermal heat pumps represent another way to harness the heat found deep in the Earth's core. This energy from just ten feet beneath the Earth's surface is somedia type="youtube" key="-ajqiPe_9Ko" height="385" width="480" align="right" useful because it does not fluctuate very much, staying at around 10°C to 15°C year round, unlike the temperatures in most of the world, which vary considerably with the seasons. Geothermal heat pumps are a type of direct usage (the first class of geothermal energy) that regulate temperatures in buildings using the relatively constant heat under the surface. They do this by transferring the heat from the ground in summer and performing the reverse in winter. This principle of heat exchange has been applied locally to downtown business buildings in Toronto. Deep lake water cooling involves the taking up of cold water (4°C) from the bottom of Lake Ontario and exchanging heat with a specialized water supply loop. The video at right summarizes clearly how geothermal heating works (as a direct usage process, not in the generation of electricity) and some of its advantages.

History of Geothermal Energy
Archaeology has shown that geothermal energy was first used 10 000 years ago by Paleo-Indians who settled near hot springs. The very first electric plant powered by geothermal energy was built in 1904 in Larderello, Italy. It's initial demonstration had steam emerging from the ground power a small turbine, which in turn lit up 5 lightbulbs. In 1913, the simple demonstration of power morphed into a fully-constructed power plant, outputting 250kW to power the Italian electric railroad system. The success of this plant showed, and the trend of building geothermal power plants spread to other countries, including Canada, the United States of America, Iceland, and other countries, including New Zealand, Japan, Mexico, and Hungary.

Canada
In Canada, there are no official geothermal power plants. There are several locations throughout Canada that have the potential to produce huge amounts of electricity from geothermal power, including in British Columbia, PEI, the Prairies, and in the Arctic. Between 1974 and 1982, significant research was done to investigate the viability of Mt. Meager as a site for geothermal energy production which led to BC HYDRO drilling a test station there in 1981. BC HYDRO encountered temperatures up to 250°C, but they discarded their plan to build a 50MW power plant. However, in the 1990s, other companies began working to revive the lost plan. . Today, Western GeoPower Corporation is exploring the options of building a geothermal power plant at Mt Meager, estimating that it could possibly generate 100-250 MW of electricity for the country if it gets built. There are, however, geothermal heat systems available to power individual buildings available in Canada. Several homes and individual buildings have installed one of these systems, which heats or cools the house while heating the water in the hot water tank(s) as well. The Canadian government is offering incentives to Canadians to use renewable energy sources as power, and geothermal energy is slowly becoming more and more popular.

USA
The United States of America is far more advanced in the field of geothermal technology than Canada, with 22 power plants in California, Hawaii, Nevada, and Utah. The very first geothermal power plant was built in 1960 in The Geysers, California. It produced 11MW of power, and still exists successfully today. Up until 2000, the US developed new power plants in each of the 4 states. Research has been done in Raft River, Idaho, where the US Department of Energy (DOE) set up a demonstration power plant between 1974 and 1982. It closed in 1983 because the DOE is legally prohibited from competing with private industries, sparking many questions by nearby residents about why it was not selling electricity, since it was the first commercial-sized power plant in the world. In the 1970s, a private coal-powered electrical plant was operating nearby and therefore could not sell goethermal power as electricity. However, in 2002, US Geothermal Inc. took over the project and now outputs 10MW of power each year to sell to the public, part of a 20-year contract that was signed in 2008. Hopefully, geothermal energy will power the surrounding area after the 20-year contract is up, making the US a more sustainably-powered country than today. In the west, 9 states have the estimated potential resources to produce more than 20% of the entire country's energy demand.

Iceland
From 1928-1930, "wells" were "sunk" near the hot springs in Thovattalaugar, near Reykjavik, in order to find hot water for space heating. In November of 1930, a school in Reykjavik was the first building to be heated by geothermal hot water. Within the year, other public buildings and some private homes were incorporated into the geothermal pipeline grid. Today, geothermal is a primary source of power on the island country of Iceland, powering over 95% of its buildings and hot water.

Other Countries
In 2007, the top 10 countries for geothermal power output were the USA, Iceland, Japan, New Zealand, the Philippines, Mexico, Indonesia, Italy, El Salvador, and Costa Rica. These 10 countries are all members of the International Geothermal Association (IGA), along with 55 other countries across the world. The IGA's mission states that they aim to "encourage research, development and utilization of geothermal resources worldwide through the compilation, publication and dissemination of scientific and technical data and information, both within the community of geothermal specialists and between geothermal specialists and the general public." Basically, the IGA compiles data from each member country or organization to share with other countries to expedite the building of efficient power plants using up-to-date technology. By being a member of this organization, hopefully Canada can build its own geothermal power plants within the next several years, much like the plants in Iceland, or its closer neighbour, the USA.

Advantages
The main advantage of geothermal power plants is an environmental one. The United States Government states that the plants: “release less than 1% of the carbon dioxide emissions of a fossil fuel plant”. Although hydrogen sulfide (the main component of acid rain) is usually found in steam and hot water, an essential component of this source of energy, plants use “scrubber systems” to remove this substance from the air. As a result, geothermal plants emit 97% less hydrogen then traditional fossil fuel burning plants. Emissions for geothermal power plants are also lower as the fuel does not need to be transported to the plant, as is the case for most traditional power plants.

As well, the land needed for the production of geothermal energy is significantly less than is required for oil, gas or nuclear power plants. Therefore, the cost in terms of land is greatly reduced when using geothermal energy. As well, sometimes other methods of energy production involve fuel, which has associated costs such as transportation and storage. Geothermal energy does not require any fuel in its production process. On a more individual basis, geothermal heat pump systems are less costly to maintain because most of the system is inside or under the building, and so not susceptible to weather-caused damage.

Another advantage of geothermal energy lies in its reliability. The United States department of energy states its average system availability to be above 90%, which is much greater than that of coal (averaging 75%). This means that geothermal energy is considered to be a "base-load power" (any source, such as fossil fuels, where energy can be produced at a steady rate at any given time). Geothermal energy is therefore one of few base-load power sources that is also renewable, given that wind and solar energy can only be generated when the wind is blowing or the sun is shining, respectively.

Geothermal energy is also less expensive for consumers than many other alternatives, averaging at three to five cents per kilowatt hour currently in the United States. In comparison, the total rate for electricity (which is mostly derived from fossil fuels such as coal) averaged 10.72 cents per kilowatt hour in 2010 to date.

Thermal pollution created from other forms of energy production, such as the burning of fossil fuels or nuclear power, is the disposal of unnecessary heat into lakes, rivers, and other bodies of water. This can be avoided in the production of geothermal energy because sometimes harmless greywater (wastewater that contains environmentally-harmless materials) is injected back into the wells after energy is produced to avoid heat escaping into bodies of water, raising the water temperature and changing the habitat plants and animals live in.

Disadvantages
A major disadvantage of geothermal energy are the geographic limitations of this source. Geothermal energy can only be harnessed at specific geographic locations where geothermal properties are present (active regions on Earth). This results in the resource being inaccessible to many inactive regions of the world. Implicit in this is another disadvantage - the most suitable places for geothermal plants are at plate boundaries, where many volcanoes form. Most companies, however, are reluctant to build geothermal plants in the potentially unstable area near a volcano. As well, some of the these specific geographic locations are high up in the mountains or near the poles, rendering them nearly inaccessible to the rest of the world.

Problems can also be found once a plant has been established. Some sources may stop emitting steam suddenly for any length of time, sometimes lasting more than ten years. This is highly unlikely however, and is so rare that the energy source is still considered to be base-load (see above). In relation, no one knows the lifespan of a geothermal s ource. Some sources have continued emitting dry-steam at the same rate for years, such as the plant in Larderello, Italy, however other plants have known to show a decline in the steam available, such as at the plant in Wairakei, New Zealand. With this information, we can assume the possibility that wells may run dry eventually.

The depth of geothermal wells also dictates the area that can use the power provided at the plant. Deep wells can transmit power to turbogenerators, which can therefore transfer the electricity produced over a long distance efficiently. However, shallower wells can only produce electricity for the immediate local area for heating purposes only, and heat cannot be transported efficiently over a long distance. Shallower wells are effective in Iceland since cities like Reykjavik, Iceland, are built near the hot springs that provide geothermal heat.

More Information
The video below is of a lecture offered at Stanford University by Cornell University professor Jefferson Tester. In it, he discusses the current application of geothermal energy and the ensuing advantages and disadvantages. He goes on to highlight the results of a research project that looked at data on geothermal energy for the last 30 years and analyzed it to provide predictions and suggestions for the future. media type="youtube" key="_BmPMl8H4pU" height="385" width="480"