Geothermal Energy Facts: Geothermal Energy Pros and Cons

There is much talk about climate change, and the search for viable renewable energy sources. Everyone knows about the likes of solar, wind and wave power. But fewer have heard of geothermal, or know how does geothermal energy work. So here are some geothermal energy facts, which may help you understand the benefits and restrictions of geothermal energy.

How Does Geothermal Energy Work

The principle of this form of energy is quite simple. The ground beneath our feet gets heated by the sun on a daily basis. However, it is also a great insulator, and so retains a vast amount of this heat as stored energy. The idea is that pipes are run through a fairly large area of ground several feet down, where the temperature is more constant. Then, water is passed through the pipes, heating it.

The primary use for this type of energy is heating, as a regulated temperature can be achieved constantly with little variation dependent on time of year. It can also be used over larger areas to provide hot water, but this needs more time in the ground so more pipework and a greater area.

Geothermal Energy Pros and Cons

The advantages of geothermal energy are that once the initial investment is paid for, and energy is relatively free. And it's clean. There is little or no reliance on power from gas or electricity to provide heat, which is one of the main uses of energy in the home. The main need for electricity to run this system is for pumps to pump the water through the system. The advantages of geothermal energy are that it is cheap, once the ground works are done, and incredibly green energy. There are no emissions from the provision of heat for the home and water.

The disadvantages of geothermal energy are the initial expense and the amount of land required. It can cost thousands to dig out the land and lay the pipes. This is one of the geothermal energy problems and why it is not widely used. Another of the disadvantages about geothermal energy is that it requires a fair sized piece of land to implement. People with a fair-sized garden will be ok, but it is not possible to install in the yard of a Victorian terrace.

One possibility that some people use is a new system where pilings are drilled into the ground, with the pipe work in the foundations. Because pilings go much deeper into the ground, they gain the distance that is required underground to heat the water. This is great for new build homes, but obviously cannot be achieved in older homes.

How Many People Use Geothermal Energy

Because of the initial costs and need for space, geothermal energy is not widely used. It is becoming more popular in single builds however, and could provide an efficient method for providing heat for buildings such as apartments and new build housing estates through district heating systems or individual heating through pipes in the pilings. Because it is so expensive, it is unlikely that house building companies will install the systems in homes in the near future. But hopefully it could become the way we provide all our heat energy needs in the future.  (ArticlesBase SC #397739)

Introduction to Geothermal Energy

Our earth's interior - like the sun - provides heat energy from nature. This heat - geothermal energy - yields warmth and power that we can use without polluting the environment.

Geothermal heat originates from Earth's fiery consolidation of dust and gas over 4 billion years ago. At earth's core - 4,000 miles deep - temperatures may reach over 9,000 degrees F.

The heat from the earth's core continuously flows outward. It transfers (conducts) to the surrounding layer of rock, the mantle. When temperatures and pressures become high enough, some mantle rock melts, becoming magma. Then, because it is lighter (less dense) than the surrounding rock, the magma rises (convects), moving slowly up toward the earth's crust, carrying the heat from below.

Sometimes the hot magma reaches all the way to the surface, where we know it as lava. But most often the magma remains below earth's crust, heating nearby rock and water (rainwater that has seeped deep into the earth) - sometimes as hot as 700 degrees F. Some of this hot geothermal water travels back up through faults and cracks and reaches the earth's surface as hot springs or geysers, but most of it stays deep underground, trapped in cracks and porous rock. This natural collection of hot water is called a geothermal reservoir.

In the United States there are enough geothermal power plants to generate electricity and power for three and a half million homes (two thousand seven hundred megawatts).

How We Use Geothermal Energy Today:
 

Today we drill wells into the geothermal reservoirs to bring the hot water to the surface. Geologists, geochemists, drillers and engineers do a lot of exploring and testing to locate underground areas that contain this geothermal water, so we'll know where to drill geothermal production wells. Then, once the hot water and/or steam travels up the wells to the surface, they can be used to generate electricity in geothermal power plants or for energy saving non-electrical purposes.

In geothermal power plants steam, heat or hot water from geothermal reservoirs provides the force that spins the turbine generators and produces electricity. The used geothermal water is then returned down an injection well into the reservoir to be reheated, to maintain pressure, and to sustain the reservoir.

There are two types of power plants: a Flash Steam Power Plant and a Binary Cycle Power Plant.

Flash Steam Power Plant:

Flash steam plants are the most common type of geothermal power generation plants in operation today. They use water at temperatures greater than 360° F (182° C) that is pumped under high pressure to the generation equipment at the surface. Upon reaching the generation equipment the pressure is suddenly reduced, allowing some of the hot water to convert or "flash" into steam. This steam is then used to power the turbine/generator units to produce electricity. The remaining hot water not flashed into steam, and the water condensed from the steam is generally pumped back into the reservoir.

Binary System:

In the Binary system, the water from the geothermal reservoir is used to heat another "working fluid" which is vaporized and used to turn the turbine/generator units. The geothermal water, and the "working fluid" are each confined in separate circulating systems or "closed loops" and never come in contact with each other. The advantage of the Binary Cycle plant is that they can operate with lower temperature waters (225° F - 360° F), by using working fluids that have an even lower boiling point than water. They also produce no air emissions.

Is It A Viable, Long-Term Solution For The Future?

Environmental Issues:

There are little to no emissions

Geothermal power plants, like wind and solar power plants, do not have to burn fuels to manufacture steam to turn the turbines. Generating electricity with geothermal energy helps to conserve nonrenewable fossil fuels, and by decreasing the use of these fuels, we reduce emissions that harm our atmosphere.

It is environmentally friendly

Geothermal installations don't require damming of rivers or harvesting of forests -- and there are no mine shafts, tunnels, open pits, waste heaps or oil spills.

Technological Issues:

The power plants are reliable

Geothermal power plants are designed to run 24 hours a day, all year. A geothermal power plant sits right on top of its fuel source. It is resistant to interruptions of power generation due to weather, natural disasters or political rifts that can interrupt transportation of fuels.

The power plants have flexibility

Geothermal power plants can have modular designs, with additional units installed in increments when needed to fit growing demand for electricity.

Geothermal energy can be extracted from anywhere there are hot spots, U.S. to Third-World

Geothermal projects can offer all of the above benefits to help developing countries grow without pollution. And installations in remote locations can raise the standard of living and quality of life by bringing electricity to people far from "electrified" population centers.

Thousands more megawatts of power than are currently being produced could be developed from already-identified hydrothermal resources. With improvements in technology, much more power will become available.

Usable geothermal resources will not be limited to the "shallow" hydrothermal reservoirs at the crustal plate boundaries. Much of the world is underlain (3-6 miles down), by hot dry rock - no water, but lots of heat. Scientists in the U.S.A., Japan, England, France, Germany and Belgium have experimented with piping water into this deep hot rock to create more hydrothermal resources for use in geothermal power plants.

As drilling technology improves, allowing us to drill much deeper, geothermal energy from hot dry rock could be available anywhere. At such time, we will be able to tap the true potential of the enormous heat resources of the earth's crust.    (ArticlesBase SC #171771)