What is Geothermal Energy?
The term ‘Geothermal’ is a derivative of two Greek words, ‘geo’ meaning earth and ‘thermos’ meaning heat. This implies that geothermal energy is a form of heat energy generated within the Earth.
This ‘heat energy’ is transmitted from the source of heat (the earth’s core) to a reservoir housing a meteoric fluid capable of storing this energy until it escapes or is tapped for use.
Geothermal or Hydrothermal energy and its capacities has been discovered for quite a while now and is not a new development but it is taking a while for some countries to implement for power generation and the likes.
Brief History of Geothermal Energy
Geothermal Energy had previously been used as early as 10,000 years ago by locals in North America for spiritual activities, bathing, washing etcetera, but it was first used for the purpose of electricity generation and industrial use in the year 1904 in Italy by an Italian Scientist, Prince Ginori Conti who was able to power a small generator supplying power to a few light bulbs. Commercial use of this form of energy begun in 1913 in Laderello, Italy where a plant was able to harness geothermal energy to produce 250 kilowatts (kW).
Soon after, developments in Geothermal Energy in a handful of countries and states followed. For example, In New Zealand, 1958, a geothermal plant sprung up. In Mexico, 1959, researchers were made and a geothermal energy plant was set up. The United States of America even followed suit in the year 1960 and dived into exploration of geothermal energy sources and generation and by 2015 a lot more than 80 countries were already exploiting geothermal energy.
But Just How Does It (Geothermal Energy) Work?
Geothermal Energy is generated from the natural heat contained within the Earth, and when you hear heat, you think magma; when you hear magma, you think high temperature, pressure and high depth levels.
Most geothermal systems are found at high depths underground and can most often not be detected on the surface unless the geothermal fluid manages to find its way to the surface through permeable rocks and fractures.
What is a Geothermal System?
A geothermal system consists of a heat source, a reservoir and fluid.
- The heat source is usually a magmatic intrusion at a shallow depth. It conducts heat from the earth core and even sometimes from the earth’s natural radioactivity.
- The reservoir is simply the housing for the high-temperature fluid. It is permeable and overlain by an impermeable rock system which keeps fluid trapped in.
- The geothermal fluid is meteoric water in either liquid or vapor state and it conducts geothermal energy from the magmatic intrusion. This fluid may escape to the surface through fractures or perforations formed as a result of tectonic movements which may surface in the form on geysers, hot springs, warm springs, etc.
Although high temperature fluid may escape and may even be produced to the surface, these geothermal fluid can be replaced naturally by meteoric water and artificially, pumps can also be used to fill vacuum in the reservoir with water.
Geological methods of exploration, geophysical surveys, hydrogeological exploration, geochemical surveys and even thermal techniques are employed to detect the presence of a geological system and even create a realistic model of the underground reservoir and its potentials. After which exploratory wells are drilled to intercept the geothermal system and rightly confirm previously gotten data from surveys and analysis.
After gathering as much information and the system is deemed to be commercially viable, a production well is drilled for the process of producing hydrothermal fluids. If the fluid is hot enough, steam bubbles form within the hot liquid and hence produces the fluid naturally to the surface. On the other hand, if the fluid is not as hot, artificial downhole pumps are introduced for production.
What exactly can hydrothermal energy be used for?
Uses of Geothermal / Hydrothermal Energy
Fluids on reaching the surface can be used as is, that is, direct use for bathing, heating, cooling etcetera. It can also be introduced into turbines/generator units (with or without the use of heat exchangers) to produce electricity.
Which is the world’s largest geothermal station?
Producing with a capacity of 900 Megawatts, the largest geothermal plant, Geysers Geothermal Complex, can be located North of San Franscico, United States. The station utilizes about 22 power plants to generate this much of geothermal energy.
Geothermal Energy In Nigeria
Although research in Nigeria has found out of the many geological evidences of geothermal systems, this form of energy is yet to be harnessed in the country Nigeria. Now let us examine the geothermal energy resources we have in Nigeria.
- Ikogosi Warm Spring: Ikogosi warm springs is a southwestern tourist center found in Ikogosi, Ekiti State, Nigeria. Researches and surveys have come to discover that the warm spring has a temperature of 70°C at the source and 30°C at the confluence where the warm spring meets with a cold spring.
- Rafin Reewa Warm Spring: Found in the North Central part of the country Nigeria, Rafin Reewa warm spring in Plateau State has fluids reaching a temperature of 42°C.
- Wikki Warm Spring: Conducting a temperature of about 39°C, this warm spring is located in Bauchi, north eastern of Nigeria.
- Lamurde Anticline Warm Spring: This warm spring associated with the Lamurde anticline located in the North of the Benue trough has a temperature of 54°C.
- Bida Basin: Subsurface temperature data gotten from the Bida basin shows a temperature gradient of 2 – 2.5 °C/100m and it houses one of the hottest springs reaching approximately 54°C.
- Niger Delta Basin: Within the Niger Delta Basin, temperature gradients collected during research showed 3.3 – 4.7°C/100m.
- Anambra Basin: During the collection of data from the Anambra Basin for geothermal analysis, samples were collected from 17 different points and these samples were analyzed to show a temperature gradient of 2.5 – 4.9°C/100m and the estimated heat flow was 48-76 MW/M2.
Lots of geothermal energy resources literally laying at our feet but are not being exploited as yet.
Pros and Cons of Geothermal Energy
Pros / Merits
- Geothermal energy is renewable.
- Geothermal energy is environmentally friendly and sustainable.
- Geothermal energy is cost effective.
- Geothermal energy can help achieve the net-zero goal.
- Geothermal energy is natural.
- Geothermal energy can supply power constantly without seasonal variations.
Cons / Demerits
- Geothermal energy is limited to areas where tectonic plate boundaries and activities, volcanic activities can be found.
- Geothermal energy releases H2S and CO2 if fluid is exposed to the atmosphere during the exploration phase.
- Some geothermal systems are located deep underground and may not be readily accessible as some would be.
With the distribution of geothermal systems within Nigeria, warm springs and geysers, there are chances that geothermal energy can be utilized to solve our energy needs domestically and even for industrial applications if the right technology and infrastructure is provided.
What do you think? Do you vote geothermal energy or Not? Voice out your opinions in the comment section.