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Geothermal energy

Introduction

Geothermal energy should play much bigger role in supplying global energy demand in years to come. Geothermal energy is non-carbon based energy source that is environmentally friendly, and doesn't release harmful greenhouse gases into the atmosphere. Almost all energy experts agree that geothermal energy is very abundant renewable energy resource that has more than enough potential to satisfy energy needs of large part in the world.

Geothermal power plants info

Geothermal power plants use geothermal energy of our planet to generate power, and most geothermal energy is found along major plate boundaries where earthquakes and volcanoes are concentrated.

There are three basic types of geothermal power plants: 1.dry steam plants that use steam piped directly from a geothermal reservoir to turn the generator turbines. 2.flash steam plants that operate by taking high-pressure hot water from deep inside the Earth and convert it to steam to drive the generator turbines. 3.binary cycle power plants that operate by transferring the heat from geothermal hot water to another liquid, and afterward this second liquid is turned into the steam that drives turbines.

The first geothermal power plant was built in Landarello, Italy in 1904. This plant became commercial in 1911.

In 2007, all world's geothermal power plants supplied only 0.3% of global electricity demand.

Geothermal power plants are predominantly built on the edges of tectonic plates but with the recent improvements in drilling and extraction techniques they should be able to cover much larger geographical range.

Geothermal power plants require high investments but once built have very low maintenance and operational costs.

The largest group of geothermal power plants in the world is located at The Geysers, a geothermal field in California, United States.

Currently operating geothermal power plants emit an average of 122 kg of CO2 per megawatt-hour of electricity, which is very small amount compared to the emissions of coal power plants.

The construction of geothermal power plants can have negative environmental impact, it can affect the stability of the land, and even trigger earthquakes which of course can have negative effect on nearby ecosystems.

Unlike other power plants geothermal power plants require minimal land, and not a lot of water. Geothermal plants use 3.5 square kilometres per gigawatt of electrical production compared to 32 square kilometres for coal power plants. Also, geothermal power plants use only around 20 litres of freshwater per MWh compared to more than 1000 litres per MWh for coal power plants.

Geothermal energy costs info

With the recent development in technology geothermal energy is becoming more cost-competitive with fossil fuels. Geothermal energy uses heat stored within the Earth to generate electricity, and therefore requires no fuel, meaning that is not affected with fluctuations in fuel prices.

According to the data from the U.S. Department of energy a geothermal power plant built today would probably require about $0.05 per kWh. Operational and maintenance costs of geothermal power plants ($0.01 - $0.03 per kWh) are even lower than of coal power plants ($0.02 - $0.03 per kWh).

Geothermal energy has high startup costs, with average geothermal power plant costing around $2500 per installed kW, which is almost twice as much compared to average natural gas power plant. However, geothermal plants do not need to worry about fuel costs, and over a typical 30-year plant life the fuel costs for a natural gas plant is likely to represent twice their initial capital cost so long-term speaking geothermal power plants can be a very reasonable investment, especially if there are some tax incentives involved.

There are dozens of factors that influence the final cost of certain geothermal power plant. The most important factors are: * Costs of equipment and labor force * Terrain * Size of the plant * Power plant technology * Knowledge of the resource * Temperature of the resource * Chemistry of the geothermal water * Resource depth and permeability * Environmental policies * Tax incentives.

Geothermal power plants are characterized by high investments (exploration, drilling, and installation) but once geothermal power plant is built operational and maintenance costs are fairly low ($0.02 - $0.03 per kWh).

Recent studies have calculated that the geothermal power plant construction (with drilling costs included) will cost about 2-5 million € per MW of electrical capacity, with the levelized energy cost of 0.04-0.10 € per kW·h.

Enhanced geothermal systems have capital costs above $4 million per MW and levelized costs above $0.054 per kWh, according to the 2007 data.

The geothermal heat pump system for average home should cost around $7,500 without the drilling. The cost of drilling is usually the biggest factor affecting the final price as the cost of drilling can vary from $10,000 to $30,000, or even more, mostly depending on the terrain.

Is geothermal energy economically viable?

Cost-competitiveness is one of the factors that will play very important role in determining the future of each renewable energy source, and geothermal energy is no exception. Currently in terms of production cost, geothermal energy is very respectable energy source with 6.5 cents per kilowatt-hour, which is very similar to production costs of wind energy. Coal and nuclear power are still economically most acceptable energy sources with their 4-5 cent/kWh generation costs but if we look at natural gas production costs at 7 cents and petroleum around 10 cents, geothermal energy certainly looks to be economically viable alternative energy source.

Relatively low production costs are not the only reason why geothermal energy is economically viable renewable energy source. The fact that geothermal energy doesn't depend on weather is probably her main economic advantage since this gives geothermal energy excellent base load electricity. Solar energy and wind energy do not have this advantage since sun doesn’t shine every day, nor does the wind blow all the time. Geothermal energy doesn't have this problems, heat from Earth's core is available all the time, meaning that with geothermal energy it is fairly easy to predict the amount of generated electricity. This may not seem that big deal to some of you but companies that signed long-term projects definitely want to have a certain data, without have to worry about factors like underproduction or "wasted" production which is often the case with solar and wind energy.

Now, lets talk little about capital costs. Geothermal capital costs are relatively low. This is because geothermal energy projects usually require less land compares to wind or solar energy projects. Compared to nuclear and even coal power plants geothermal power plants also have one big advantage in form of fewer permits because they are less harmful to environment than nuclear and coal power plants. And since there are no emissions like this is the case with fossil fuels there is also no need to capture or sequester carbon emissions, a requirement that can add 40-60% to capital cost of fossil fuel projects.

Another big factor that makes geothermal energy economically viable is also very high load factor. Load factor is the difference between how much the generator is designed to produce and how much it actually produces. The smaller the difference, the higher the load factor. The load factor of conventional power stations is on average around 50%, wind farms have the load factor around 30-40%, while geothermal energy has load factor close to 90% due to the fact that geothermal energy is impervious to weather conditions.

As you can see geothermal energy is not only energy source recommended from the environmental point of view but also from economic point of view, since it can easily compete with most fossil fuels, and provide reliable source of energy to many parts of the world.

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