Underground Energy - Geothermal

Happy Valentine Day~

So are the couples out there ready for that special day? Surely there will be a lot of chocolates and flowers booking from those shops. Valentine's Day is a quite a special day for couples to celebrate their loves towards each other. Of course I am also one of them and I have actually booked a romantic place for my girlfriend.

As I was travelling to Philippine for a renewable energy project, I was overwhelmed by the hot weather. The heat wave was really reaching up to 37 Degrees Celcius. If you think that is hot, imagine how it feels like at below ground. It will be tremendously hot, but do you know that with this limitless source of energy, we can actually harness it and use it for our daily usage?

This energy source is what we called Geothermal. It's basically is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

How Does Geothermal Energy Work?

Scientists are running a race against time to find cleaner, more efficient, renewable sources of energy. One potential source that we've barely tapped is right underneath our feet. Deep inside the Earth lies hot water and steam that can be used to heat our homes and businesses and generate electricity cleanly and efficiently. It's called geothermal energy -- from the Greek words geo, or "earth," and therme, meaning "heat."

The hot lava from a volcano and the hot steam from a geyser both come from underground heat and we can use that same type of heat in our homes. There is plenty of heat in the center of the Earth. The deeper you dig, the hotter it gets. The core, about 4,000 miles (6,437 kilometers) beneath the surface, can reach temperatures of 7,600 degrees Fahrenheit (4,204 degrees Celsius). Part of that heat is left over from the Earth's formation, about 4 billion years ago. The rest comes from the constant decay of radioactive isotopes inside the Earth.

How Can It Sustain Our Daily Life?

Geothermal energy can be used in three ways:

Direct geothermal energy. In areas where hot springs or geothermal reservoirs are near the Earth's surface, hot water can be piped in directly to heat homes or office buildings. Geothermal water is pumped through a heat exchanger, which transfers the heat from the water into the building's heating system. The used water is injected back down a well into the reservoir to be reheated and used again.

Geothermal heat pump. A few feet under the ground, the soil or water remain a constant 50 to 60 degrees Fahrenheit (10-15 degrees Celsius) year-round. Just that little bit of warmth can be used to heat or cool homes and offices. Fluid circulates through a series of pipes (called a loop) under the ground or beneath the water of a pond or lake and into a building. An electric compressor and heat exchanger pull the heat from the pipes and send it via a duct system throughout the building. In the summer the process is reversed. The pipes draw heat away from the house and carry it to the ground or water outside, where it is absorbed.

Geothermal power plant. Hot water and steam from deep underground can be piped up through underground wells and used to generate electricity in a power plant. Three different types of geothermal power plants exist:

• Dry steam plants. Hot steam is piped directly from geothermal reservoirs into generators in the power plant. The steam spins turbines, which generate electricity.
• Flash steam plants. Water that's between 300 and 700 degrees Fahrenheit (148 and 371 degrees Celsius) is brought up through a well. Some of the water turns to steam, which drives the turbines. When the steam cools it condenses back into water and is returned to the ground.
• Binary cycle plants. Moderately hot geothermal water is passed through a heat exchanger, where its heat is transferred to a liquid (such as isobutene) that boils at a lower temperature than water. When that fluid is heated it turns to steam, which spins the turbines.

How To Harness Its Energy?

Basically, geothermal generation takes advantage of hot temperatures below ground, in areas where volcanic activity is high because the earth’s crust is relatively thin. Water is injected below ground; if the ground is made of a permeable rock such as sandstone, the water may already be naturally present. The water comes into contact with hot rock heated by the earth’s magma, and boils into superheated dry steam.

This steam is pushed by its natural expansion (from liquid to gas) up through the earth and into pipes, and captured to power a steam turbine, which produces electricity. The dry steam is then partially released into the atmosphere, and partially condensed and pumped back underground, along with other gases released during the process.

Pros & Cons

Experts say that geothermal energy is cleaner, more efficient and more cost-effective than burning fossil fuels, and it can reduce our dependence on foreign oil. Geothermal energy is clean because it can be generated without burning fossil fuels. Geothermal power plants release a fraction of the carbon dioxide, produced by fossil fuel plants, and they create very little nitrous oxide or sulfur gases. Reykjavik, Iceland, which heats 95% of its buildings using geothermal energy, is considered as one of the cleanest cities in the world.

PROS

• Geothermal energy does not produce any pollution.
• The power stations do not take up much room, so there is not much impact on the environment.
• No fuel is needed.
• Once a geothermal power plant is built, the energy is almost free.

CONS

• The big problem is that there are not many places where you can build a geothermal power plant (you need hot rocks of a suitable type, at a depth where we can drill down to them, and the type of rocks above is also important as it must be able to easily drill through).
• Sometimes a geothermal site may "run out of steam", perhaps for decades.
• Hazardous gases and minerals may come out from underground, can be difficult to safely dispose of.

But going through all these pros and cons of a geothermal renewable energy, in my humble opinion, the benefits of using it is still much more greater and sustainable than using the old conventional fossil fuels. The question is, will those countries which have volcanic areas (eg. Philippine, Indonesia, Hawaii, etc.), take advantage of this free renewable energy? How about those that do not have any volcanic areas at all (eg. Malaysia, Singapore, Brunei, etc.)