For example, Ormat Technologies has delivered a more than 150% gain, between January and September of 2006. As stated on their official website, http://www.ormat.com/, Ormat Technologies, Inc, (NYSE: "ORA") is a leading vertically integrated company dedicated to providing solutions for geothermal power, recovered energy generation (REG) and remote power. The Company designs, develops, builds, owns and operates geothermal and recovered energy-based power plants. Additionally, the Company designs, manufactures and sells geothermal and recovered energy power units and other power generating equipment, and provides related services. Ormat products and systems are covered by more than 70 patents. Ormat's geothermal power plants are a field-proven, mature commercial product operating worldwide, designed for outdoor installation and remote control unattended operation. Ormat has successfully supplied more than 800 MW of geothermal power plants, based on its proprietary technology, logging millions of hours of operating experience.

Magma Power Company is one of the largest geothermal companies in California. Magma Power Company searches for, develops, and sells or leases geothermal resources used to generate electric power. Magma Power is not the other California geothermal companies, because it's a pioneer in its field and almost solely responsible for creating the geothermal industry in USA. It was the first of all geothermal energy companies to start drilling for naturally produced steam way back in the mid-1950s. It's not only developing geothermal resources, but it also constructs and operates geothermal electric power plants.

Vulcan is also amongst the top geothermal power companies. It's privately owned, headquartered in Bend, Oregon and founded in 1991. The main focus of Vulcan is the development and operation of clean, renewable, non-stop baseload geothermal power plants. A 2007 third-party report estimated that Vulcan properties can supply electricity for up to 2 million Americans. The official company website is http://www.vulcanpower.com/.

Enel is one of the Italian geothermal electric companies and as you probably know, Italy is the country where geothermal energy was first utilized. Enel's substantial geothermal expertise in Italy is now being exported to North America where Enel North America is combining it with local knowledge to build a strong geothermal program. In early 2007, Enel NA acquired the rights to develop and operate four geothermal projects totaling approximately 150 MW, located in Utah, California, and Nevada. The official website of Enel is http://www.enel.it/.

Econar and Borel Geothermal are one of the most popular geothermal heat pump manufactures. Delaware is one of the China lake geothermal companies.

Here is the basic principle of operation of a geothermal power plant. People have geothermal water from the earliest times as they used to cook using the hot water that flowed from the earth's surface. The Romans were actually using to treat eye and skin diseases, while the Pompeii were using to heat buildings. Native Americans were also using geothermal energy for cooking and medicine. In present days, geothermal power plants are taking it to the next step and use geothermal energy to generate electricity. The first geothermal power plant went into operation at The Geysers in 1921. It produced 250KW of electricity.

Geothermal power plants use heat, steam, or hot water from geothermal reservoirs as they provide the force that spins the turbine generators to produce electricity. There has got to be an external force that has to make the turbine generators spin and that's exactly the purpsoe of hot water in this case, or heat, or steam. Geothermal energy is a renewable type of energy because once the geothermal water is used, it's returned down by re-injection that puts it well into the reservoir to be reheated, to maintain pressure, and to sustain the reservoir.

There are three types of geothermal power plants. These power plants are differentiated depending on the temperatures and pressures of a reservoir, so here is the list:

-Dry steam reservoir - the largest Dry steam reservoir type of geothermal power plant is The Geysers (http://www.geysers.com/). It's in the Mayacamas Mountains, located 72 miles north of San Francisco, where naturally occurring steam field reservoirs below the earth's surface are being harnessed by Calpine to make clean, green, renewable energy for homes and businesses across Northern California. The Geysers, comprising 30 square miles along the Sonoma and Lake County border, is the largest complex of geothermal power plants in the world.

-hot water reservoir - geothermal reservoir that produces mostly hot water. The power plant that utilizes it is called a "flash" power plant.

-reservoir with temperatures between 250 and 360 degrees F - Such a reservoir doesn't have water hot enough to flash enough steam, but a binary power plant can still use it to produce electricity.

Pictures of geothermal power plants can be easily found on the Internet using the Image feature of the Google search engine.

The performance of the entire system will noticeable deteriorate if airflow is much less than 350 cfm per ton. But there is a fix to that problem, so you shouldn't worry too much about it. A good technician can increase the airflow in no time by cleaning the evaporator coil and increasing the speed of the fan. If that doesn't help, then some modifications on the ductwork might be required.

In case there are dirty coils and filters, these parts should be changed. To avoid having such problem in the first place, clean the coils and filters on a regular basis.

Another problem could be the heat pump making too much noise. Although the entire system is designed to run very smoothly, there cases where the pump generates extreme levels of noise. A properly-working heat pump model has an outdoor sound rating of 7.6 bels or lower. If the problem isn't in the model, a possible source of the problem is the location. You should install the heat pump outdoor unit away from any windows and adjacent buildings. You should also mount the unit on a noise-absorbing base.

There could be potential winds and frosting problems related to your heat pump. But that could be avoided by choosing a good location in the first place. The location of the heat pump outdoor has a great impact on its efficiency. Rule is that all outdoor units shouldn't be facing high winds, as they can cause frosting problems. Therefore, try to strategically place a bush or a fence.

As much as you don't to have any geothermal heat pump problems, no system is perfect so you might need some sort of a fix from time to time. Good news is that heat pumps have a guarantee, so if you are within that period, the company that sold the equipment to you will be responsible for fixing it. As you know, such guarantees vary from manufacturer to another. Some manufacturers offer plans that have like 10 years of total coverage, protecting you against rising repair costs, and with no limit on the number of repairs. That's what you should be looking for. But the more common type of warranties actually cover the different parts of the heat pump system, so for example the underground loop used in the geothermal system can be guaranteed to last 25 to 50 years, while the compressors and outdoor coil typically have coverage for a ten-year period.

The great thing about geothermal exchange is that you don't have to go anywhere to find it, it's beneath your feet. Fact is that the surface of our planet absorbs nearly 50% of the sun's energy that reaches it and stores it in the form of heat. And with a geothermal exchanger you can make use of this energy without polluting the environment. Air temperature varies depending on the season, climate and weather, but the underground temperature remains constant throughout the entire year. Of course, here we are talking about going several hundred feet deep. Experts said that just 200 feet down, the Earth's temperature stays about 55 degrees year around and that is what you pull into your home. The initial cost of geothermal heat exchange is high, but it's well worth it because of all the saves you will get in the long run as energy bills will be 50 to 70 percent less.

Direct-exchange geothermal heating and cooling systems have been around for more than a decade. Of course, there are certain things that influence the efficiency of the whole system. First of all, soil type is very important. It's all about the heat transfer here so if the soil's density is too high, it will deteriorate the efficiency. Air and moisture content as well as soil composition also play a major part. The worst type of soils are the dry ones, like dry sand. The heat transfer rate is highest when there is a minimum amount of air and the greatest amount of compaction of soil molecules around the ground loop.

But if the soil under your home is not perfect, that doesn't mean you should give up. To solve that problem, some owners actually go about bringing soil from a different location. Of course, this will seriously increase the costs. Another workaround is surrounding the loop with a dense fill material.

Geothermal exchange systems are ideal for every location and every type of building. Commercial and residential properties can make a full use out of it.

The most expensive component of the entire geothermal heat pump system is the ground loop. The main things on which this price depends are labor rates in the given area and characteristics of the location where the digging and drilling will be made. Installing the ground loop will cost you anywhere between $1,000 and $3,000 per installed ton. Bottom line is that you should be prepared to pay between $2,500 and $10,000 more for a 3-ton GHP system compared to an air source heat pump system.

The reason why geothermal heat pumps are a really efficient way of condition a home is that they combine high efficiency with low operating cost. According to the EPA, geothermal heat pumps can save homeowners 30 to 70 percent on heating and 20 to 50 percent on cooling costs over conventional systems. As a result of that, heating and cooling savings can range between $358 and $1,475, annually.

Here is a real-life example. After running a system like that for just a month, a customer received his electric bill and the results were quit astonishing. For the course of an entire month, the bill was only $60 higher compared to the previous month (without the system), so the actual heating bill of this family was just $60, which is a great result for a 4 tons system in a rather large home. This family being mentioned in our non-fictional example paid around $10,000 for the geothermal equipment and another $9,000 for the ground loop. So the entire cost was about $19,000 which of course is a lot of money, but if you think about all the savings you will make in the future and the fact that you are not polluting the environment by burning fuels or propane, you will see that it's totally worth it. Competing HVAC systems are even more expensive in other countries and the same family in this example was quoted $16,000 for an oil-fired furnace and electric central air conditioning system.

ECONAR, http://www.econar.com/

ECONAR has been producing GeoSource geothermal heat pumps in Minnesota for a quarter of a century. Minnesota's cold winter climate has driven the design of ECONAR's heating and cooling equipment to what is known as a "ColdClimate" geothermal heat pump. This cold climate technology maximizes the energy savings available in heating dominated regions without sacrificing comfort, thus making ECONAR the leader in cold climate heat pump technology. Extremely efficient cooling, dehumidification and optional domestic hot water heating are also provided in one neatly packaged system. GeoSource Heat Pumps can be used in residential or commercial applications. Common geothermal applications include: homes, churches, banks, schools, car washes, fish farms, ice rinks, swimming pools, restaurants, and anywhere heating, cooling and hot water is required. Safety and comfort are both inherent to, and designed into ECONAR's geothermal heat pumps. Since the system runs completely on electrical energy, your entire home will have the safety of being gas free. ECONAR, through installation of its heat pumps, has contributed significantly to the reduction of global warming through the elimination of fossil fuels in many homes and businesses. All of ECONAR's products are safety certified and its heat pumps are performance certified by internationally recognized third party testing laboratories.

Boreal Geothermal, http://www.boreal-geothermal.com/

Boreal Geothermal Inc. was created to offer a broad range of uncomplicated, economical, durable space conditioning systems based on 21st century renewable energy technology. Conscious of the serious environmental issues of our times, Boreal Geothermal Inc desires to actively contribute to the reduction of energy consumption, greenhouse gas emissions, lower the impact of the human activities on the environment while preserving the comfort and quality of life for all made possible by innovative technologies. Boreal ® Forced Air Geothermal Heating and Mechanical (Active) Cooling (AC) series and Boreal ® Forced Air Geothermal Heating and Passive (Direct) Cooling (DC) series geothermal heat pumps are available in a variety (both horizontal and a vertical) of configurations with outputs from 35,000 to 75,000 Btu's. Boreal ® Forced Air geothermal heat pumps absorbs heat from the ground via one of the three collector systems (horizontal or vertical ground loops or two well system), used with forced air and provide heating and cooling and domestic hot water.

Gas geothermal heat pumps provide a real solution to home heating problems. No more high heating bills, humidification problems, cold drafts or hot blasts, and environmental side effects of burning fuels. Forget about the traditional age old technology that goes all the way back to black-and-white television, VCRs, and bias-ply tires. Thousands of homeowners across the country have already discovered the power of geothermal heating and cooling, what about you?

Geothermal systems have proven themselves over the past few decades of operation in all parts of USA. There are several manufacturers and many contractors in every area so there is stiff competition which ensures quality installation and service at a fair price.

Some people are concerned that a gas geothermal heat pump might be difficult to install, but there is no such thing. Most units are easy to install, especially when they are replacing another forced air system. They can be installed in areas unsuitable for fossil fuel furnaces because there is no combustion, thus, no need to vent exhaust gases. Ductwork must be installed in homes that don't have an existing air distribution system. The difficulty of installing ductwork will vary and should be assessed by a contractor.

The average life span of a gas geothermal heat pump is 22 years, estimated by the U.S. Department of Energy. so the initial investment will definitely pay itself back. Gas geothermal heat pumps save money, reduce emissions, and are cost effective compared to conventional heating and cooling technologies. Other heating systems might be less expensive initially, but their level of efficiency is much lower. On top of all that cost effectiveness, geothermal heat pump systems offer aesthetic advantages, there really quiet during operation, free or reduced-cost hot water, improved comfort, and a host of other benefits.

The open loop geothermal heating system has been used with great success for several decades now. Open loop systems work by drawning an aquifer through one well, which is then discharged to the same aquifer but through a second well that is distanced from the first one. Such Geo-Thermal Heating systems are very popular in areas where they are allowed because they the temperature of ground water is almost constant throughout the year.

Closed loop system on the other side seem to be enjoying more success as they are more commonly used. When installed correctly, the closed loop system provides an efficient, economical and at the same timer reliable way of heating a given home. Such systems work by circulating water through a continuous buried pipe. Closed loops can be vertical or horizontal. The horizontal type is the most cost-effective for small installations that have sufficient land area. Up to six pipes, usually in parallel connections, are buried in trenches with minimum separations of a foot between pipes and ten to fifteen feet between trenches. Vertical geothermal heating systems are used when the soil is too shallow for trenching and the property owner doesn't want to change the current landscape. A U-tube is used in such cases, burried between 100 to 400 feet deep.

Here is the principle of operation of geothermal heating systems. The system takes advantage of the fact that the temperature below ground remains the same throughout the entire year, regardless of climate or season. The ground is able to keep a higher rate of temperature consistency because it absorbs almost half of the suns heat as it hits the surface of the earth. A Ground source heat pumps is used to move heat that already exists in the earth to provide your home with central heating.

WaterFurnace is a company manufacturing geothermal heating systems. WaterFurnace geothermal systems use the free, renewable energy found in your own back yard to save up to 70% on heating, cooling, and hot water costs. WaterFurnace manufactures and sells more geothermal systems for homes than anyone else in the business. During the heating cycle, a WaterFurnace geothermal system uses the earth loop to extract heat from the ground. As the system pulls heat from the loop it distributes it through a conventional duct system as warm air. It's interesting to note that WaterFurnace systems can do both heating and cooling. You can find out more information on WaterFurnace at http://www.waterfurnace.com/.

Another serious advantage of geothermal energy is that it's available 24 hours a day, 7 days a week. The US Department of Energy has estimated that geothermal power plants have average availabilities of 90% or higher, compared to about 75% for coal plants. On top of all that, this power is homegrown, which means the United States of America is less dependent on foreign oil.

But the list of advantages of geothermal energy doesn't end here. It's a renewable energy source, because it uses the almost unlimited amount of heat generated by the Earth's core. As humanity is facing serious environmental problems like pollution and global warming, it's of vital importance that we switch to renewable energy sources, as soon as these become sufficiently sophisticated and cheaper. New technologies are to be introduced, reducing energy and raw material consumption (cellular phones, information storage and transfer on/through electronic media), rejection of heavy infrastructure, transport avoiding fossil fuels (bicycles, electric and other non-polluting cars, airships replacing airplanes, etc).

Geothermal technologies offer many environmental advantages compared to traditional power generation. As mentioned, the biggest one is that emissions are low, with the only excess being steam which is emitted by geothermal flash plants. No air emissions or liquids are discharged by binary geothermal plants, which the US Department of Energy plans to make the dominant technology in the near future. Salts and dissolved minerals contained in geothermal fluids are usually re-injected with excess water back into the reservoir at a depth well below groundwater aquifers. This recycles the geothermal water and replenishes the reservoir.

Of course there are advantages and disadvantages of geothermal energy. As a disadvantage can be taken the fact that it requires a substantial initial investment to build a geothermal power plant. Another disadvantage is that it can only be build on certain places with special characteristics. Search the web for more advantages disadvantages of geothermal energy.

Geothermal comes from the Greek words "Geo" (earth) and "Therme" (heat). So in that sense, you have probably already figured out that geothermal energy is heat from within the earth. We can actually use the steam and hot water inside the earth's core to heat buildings and produce electricity. A very important eco fact is that geothermal energy is a renewable energy source, since the water is recovered by rainfall, while the heat itself is produced all the time within the earth.

One of the most interesting geothermal energy facts is that geothermal energy is produced 4,000 miles below the surface in the earth's core. You will probably be amazed to hear that the temperatures in there are hotter than the sun's surface. The reason for this phenomenon is a radioactive process that takes place in all rocks. People from all parts of the world have started using geothermal energy to heat their homes and generate electricity by digging deep holes and pumping the heated underground water. But that's just one the uses and it's called direct use. Geothermal power plants are built around geothermal reservoirs, because they require water or steam at very high temperature (like 300 to 700 degrees Fahrenheit). Hot water near the surface of the earth is piped directly into buildings and used for heating. In Reykjavik, Iceland, 95% of the buildings use geothermal energy for heating, but that's due to the uniqueness of this country since that's the country with the largest number of geysers in the world.

Geothermal energy is one of the best types of energy when it comes to how safe it is for the environment. We have other sources which are far more dangerous and cause much more pollution, whereas geothermal energy has almost zero negative impact on the environment. The biggest advantage is that it doesn't require the burning of fuel to generate electricity, so there is practically no emission. A geothermal power plant releases only about 1 to 3 percent of the carbon dioxide emissions of a fossil fuel plant and emit 97 percent less acid rain. The best thing is that after the water and how steam have been used, they are reinjected back into the earth.