As the world undergoes a tremendous transition in terms of achieving net-zero emissions by 2070, according to the UN COP26 plan in November 2021, renewable energy sources for electricity generation are rapidly surfacing, and geothermal energy is one of them. Geothermal energy uses the Earth’s natural heat to its advantage.
Geothermal energy is stored within the Earth's core, and the temperature stays around 9000 degrees Fahrenheit. This heat can be tapped to generate power by using a heat exchanger. The number of people using geothermal energy for power has increased in the last decade.
For generating power from geothermal energy, the Earth’s surface has to be dug deep as geothermal energy lies in the rocks and fluids beneath the Earth’s surface.
As steam trapped in the Earth’s crust is used to generate power, the wells are dug miles deep to access those hot steams. Then, the rising hot steam from the underground reservoirs is used to drive turbines to generate electricity.
There are three types of geothermal power plants, namely, dry steam, flash, and binary. These have varied ways of driving the turbines depending upon the intended usage.
Dry steam power plants taper into the underground resources of steam. The steam is carried out to power plants from underground wells through pipes. In power plants, piped steam is used to drive turbines/generators.
Flash steam power plants utilize geothermal water reservoirs with temperatures greater than 360 degree Fahrenheit. Due to its high pressure, the extremely hot water flows upward through wells. The pressure decreases, and the boiling water turns into steam as it surfaces. Then, water and steam are separated so that the steam can be used to drive the turbine engines.
The leftover water and condensed steam are sent back to the geothermal reservoirs.
Binay steam power plants draw steam from geothermal reservoirs with lower temperatures (225-360 degree Fahrenheit). The steam piped from the reservoirs is mainly used to boil organic compound liquids. The vapors of the organic compound liquids are then used for driving turbines.
The water is sent back into the reservoirs for reheating.
Geothermal pumps transfer the captured heat to transfer the energy generated from hot steam to our water supplies for warming and cooling homes and buildings.
Presently, there are two types of heat pumps used that obtain energy from the water in magma and molten rocks:
- Closed-Loop Geothermal Heat Pumps
- Open-Loop Geothermal Heat Pumps
A geothermal energy resource needs three things to generate electricity:
1. Fluid: Enough fluid must exist naturally or would need to be pumped into the reservoir.
2. Heat: The Earth’s temperature increases with depth and is different for different geographical locations.
3. Permeability: To access heat from the earth, the fluid has to get in contact with heated rock either through natural fractures or by simulating the rock
The conventional geothermal resources have the above resources naturally. However, in places where these natural geothermal resources do not exist, the heat of rocks is used by creating artificial permeability of fluids extracting that heat. Such geothermal systems are called enhanced geothermal systems (EGS).
The global enhanced geothermal system market was valued at $1,841.4 million in 2020. It is projected to reach a value of $3,673.1 million by 2030, at a CAGR of 7.1% during the forecast period 2022-2030.
Geothermal energy, like every other renewable source of energy, will never deplete because the core of the Earth will never run out of heat. It is considered one of the most feasible renewable sources and incredibly viable to be utilized in industries on a massive scale.
- Geothermal energy promises carbon-free emissions.
- Even the small amount of greenhouse gasses produced during geothermal energy generation is merely one-sixth of what natural gas emits.
- It is always available for access.
- It is a silent source of energy that does not require large spaces for extraction.
- Geothermal energy is renewable, ever-lasting, reliable, and eco-friendly.
The U.S., Indonesia, and the Philippines are the global leaders in producing geothermal energy, and these three countries have plenty of geothermal energy-associated projects under development.
New technological developments keep making appearances to mark the onset of safer, more effective, and efficient geothermal energy. Numerous oil-based industries are joining hands to lead innovative, ground-breaking projects to uplift the future of geothermal energy.
- The Geysers Geothermal Complex
- Larderello Geothermal Complex
- Cerro Prieto Geothermal Power Station
- Makban Geothermal Complex
Even though geothermal energy turns out to be a useful resource, it is limited in its activities of generating electricity, heating, and cooling to certain pockets.
However, the future of geothermal energy is brighter. The advancing technology has solved the problem of geothermal energy being limited to certain pockets where underground hot water reservoirs are present.
The advanced drilling and rock-fracturing technologies promise to dig 2.5 miles deeper for fracturing the rocks, so that water is injected in one well and can be carried on through these fractured passages of rocks. It also propels the energy, reduces cost, and has a longer field lifetime.
North America is the largest market for enhanced geothermal systems. The U.S. is the primary area driving expansion in the North America enhanced geothermal energy market.
With the rapid development in technology, advancements in green energy seek to remove the cons of geothermal energy and raise awareness among consumers.