We need the energy to light up our homes and offices, cook our food, and power our appliances and vehicles. There are many energy sources in the world –nuclear, fossil, and renewable sources like wind, solar, hydropower, and geothermal. The energy is converted to electricity, a secondary energy source, to your home and business.
Geothermal energy is a sustainable source of energy as it is contained within the Earth. The sources of this energy can be the shallow underground reservoir of steam and hot water, magmas, and other rocks in the Earth’s depths. In many parts of the world, it has been used for thousands of years already.
Geothermal heat pump systems can tap anywhere into the shallow ground or upper 10 feet of the Earth’s surface that maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). The system consists of a heat pump, a heat exchanger, and an air delivery system (ductwork). During winter, heat from the heat exchanger is removed by the heat pump and pump into the indoor air delivery. Reversely, during summer, the heat pump moves heat from the indoor air into the heat exchanger.
Meanwhile, at depths of 3 to 5 miles everywhere beneath the Earth’s surface and lesser depths in certain areas, you can get the energy from hot, dry rock resources. To tap from these resources, injecting cold water down the well. Thus, allowing circulation through the hot fractured rock, and would draw off the heated water from another well. Commercial application is not possible as of this time because the existing technology does not allow recovery of heat directly from magma, which is the bottomless and most powerful geothermal energy resource.
Advantages of geothermal energy
Extraction of geothermal energy does not require burning fossil fuels like oil, gas, or coal. Thus, it becomes a “carbon-free, renewable, sustainable form of energy that provides a continuous, uninterrupted supply of heat that can be used to heat homes and office buildings and generate electricity” as described by the British Geological Survey.
There is only one-sixth of the carbon dioxide produced from geothermal energy by a natural gas plant, not an intermittent source of energy like wind or solar. Its potential production could reach at least 35GW and as high as 2TW.
Binary cycle power plants release essentially no emissions (except water vapor) in the atmosphere because it is a closed-loop system. A substantial proportion of geothermal electricity in the future could come from binary-cycle plants as resources below 300°F represent the most common geothermal resource.
Geothermal energy is available 365 days a year, unlike solar and wind power. It’s also relatively inexpensive, and savings from direct use can be as much as 80 percent over fossil fuels.
However, there are some environmental issues concerning the utilization of this energy.
The release of hydrogen sulfide is a primary concern. It irritates the mucous membrane and respiratory tract. Inhalation of high levels of hydrogen sulfide can produce extremely rapid unconsciousness and death. Exposure to liquefied gas can cause frostbite injury.
The disposal of some geothermal fluids is another issue. These wastes from plants may contain low levels of toxic materials. Despite geothermal sites capable of providing heat for many decades, specific locations may cool down eventually.
A geothermal power plant is also associated with tremors where the plant is located. Construction can cause instability in the surface and can trigger earthquakes. The drilling itself may not trigger earthquakes, but the rupturing of steam and the subsequent return of the used water to the hot water reservoir could. The cycle leads to instabilities along fracture lines that might result in an earthquake.
The conventional way involves drilling hot rock that contains trapped water or steam in its pores spaces and natural fractures. When a drilled hole intersects these fractures, the trapped water erupts as steam due to an instant drop in pressure.
Geothermal sites may experience dryness. The many years of continuous activities, the geothermal heat coming from the reservoir below, may die down or run out of steam. The dry period may last decades, that is why it is recommended to use the heat prudently and not abuse it. Improper use can also result in a poor distribution of heat.
In 2020, the top geothermal energy producing countries includes US, Indonesia, Philippines, Turkey, New Zealand, Mexico, Italy, and Iceland. These countries lead the way in the implementation of geothermal facilities.