The Powers of the Elements: Earth and Fire


Dependant as we are on it, it is literally impossible to unplug electricity from human life. The imminent depletion of non-renewable energy sources has pushed humans to invest more on research and implementation of projects that aim to generate electricity from renewable energy sources. The powers of the four elements of nature, compared to the dominating fossil fuels, neither pollute nor damage our environment; they cannot be controlled by any one nation or industry, and are readily available for free for each human being on the surface of the Earth.

Geothermal Power

Geothermal power, as suggested by the name, is a sustainable energy generated from the heat produced in the Earth’s core. The ongoing process of decaying radioactive particles that occurs in rocks produces extremely hot temperatures exceeding that of the Sun’s surface.

Generally speaking, geothermal energy reservoirs are deep underground with no visible signs on the surface, but it could find its way up in the form of volcanoes, fumaroles or hot springs. Most of the Earth’s geothermal activity occurs in the “Ring of Fire”, an area encircling the Pacific Ocean representing the core of earthquakes and volcanic activities.

Generating electricity from geothermal power relies on steam or water geothermal resources at very high temperatures; 150°C to 370°C. Consequently, electricity generation power plants are generally built where geothermal reservoirs coming from either dry steam wells or hot water wells are located within a mile or two of the surface. The pouring steam spins a turbine that activates a generator to produce electricity.

There are three types of geothermal power plants: dry steam, flash steam, and binary cycle. Dry steam plants directly use the steam piped from geothermal reservoirs to turn the electricity generating turbines. The most common, flash steam plants, on the other hand, convert water from hydrothermal resources into steam to rotate the generator’s turbines. Remaining water and condensed steam are injected back into the ground to be used again, making it a sustainable energy resource.

As for binary cycle plants, they use the heat of geothermal water to boil another organic liquid with a low boiling point; the resulting vapor is used to drive the generator turbine. The water is then injected back into the hydrothermal reservoir to be reheated, and eventually reused.

Geothermal power is a clean source for electricity generation as it does not burn fuel in the generation process; it has very low emission levels. Power plants incorporate scrubber systems to purify air from hydrogen sulfide existing in steam and hot water. Most importantly, used water and steam are injected back into the Earth to be reused over and over again.

Solar Power

Solar energy is the primary source of renewable energy on Earth; it is from within the inner core of the Sun through a process known as nuclear fusion. Though it is 150 million kilometers away, the Sun is amazingly powerful; scientists claim that the amount of solar energy arriving to Earth in one minute is sufficient to meet our demands for a whole year, if only we could harness it in a proper way.

Among the incalculable benefits and roles it plays in sustaining life on Earth, solar energy can also be used to produce electricity. There are two different approaches to generate electricity from the Sun: Photovoltaic (PV) or solar cells, and solar-thermal technologies.

Photovoltaic devices or solar cells directly convert sunlight into electricity. The term “photovoltaic” comes from the Greek word “photos”, meaning light; and “volt”, a measurement of electricity. Solar cells are made up of silicon, one of the most common substances on Earth; the one that makes up sand.

When sunrays strike a photovoltaic cell, they may be reflected or absorbed. Only absorbed rays provide the energy needed to generate electricity as they become capable of initiating a chemical reaction. When rays strike solar cells, they move the electrons around, starting an electric current. Unfortunately, photovoltaic systems are not economical compared to other electricity generation technologies, as a single cell only produces one or two watts.

Solar-thermal systems, also known as Concentrated Solar Power (CSP), use the Sun’s heat, rather than light, to generate electricity. Most solar-thermal systems use a mirrored-surface collector to concentrate sunlight onto a receiver that heats a liquid to boiling degrees, and uses the resulting steam to power electric generators. However, solar-thermal plants require significant amounts of water for regular cleaning and cooling. Also, birds and insects can perish if they fly into the concentrated beam of sunlight.

Solar energy has great potential for the future; it is for free and presents unlimited clean energy supplies. However, the cost of building solar power plants nowadays is still relatively high compared to the amount of electricity they produce. They can also harm desert ecosystems due to the significant land they require. It is also important to remember that solar energy, evidently, will not work at night, and that its production is subjected to climate conditions, such as clouds or fog.


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SCIplanet is a bilingual edutainment science magazine published by the Bibliotheca Alexandrina Planetarium Science Center and developed by the Cultural Outreach Publications Unit ...
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