The natural heat below Earth’s surface has huge potential to become one of the greatest uses of renewable energy. Unlike solar power, this type of energy is always available. It isn’t dependent on the time of day and can be used in a more predictable way. 

Geothermal power plants are fairly easy to use and don’t require too much effort to install, wind turbines take up great fields whereas these power plants don’t require the same amount of space. Geothermal energy creates more indirect employment than any other type of renewable energy. In terms of numbers, that translates to 34 jobs per installed megawatt, much higher than the 19 created by wind power and the 12 by photovoltaic energy. In Italy alone, 2,000 gigawatts of installed power would guarantee permanent employment for 4,000 people and 30,000 other jobs.

Many of the plants also have components that can be reused and recycled. Along with this, these plants have a lifespan of about 80 to 100 years. Geothermal power systems are also known to heat and cool, and this means that they can be installed almost anywhere. In any building or location such as shopping malls.

What are the Benefits?

What are the limitations?

There are a couple of limitations that accompany geothermal energy. Among them is land instability. There were two cases, one in Germany and New Zealand where the construction of the power plants led to the sinking of the Earth’s surface. 

There is an abundance of greenhouse gasses below the surface of the earth. When geothermal energy is used, some of these gasses escape towards the surface and into the atmosphere. These emissions tend to be higher near geothermal power plants.Geothermal power plants generate small amounts of sulfur dioxide and silica emissions. The reservoirs can also contain traces of toxic heavy metals including mercury, arsenic, and boron.

The upfront costs of geothermal heating and cooling systems for homes and commercial buildings are also steep. That said, these systems are likely to save you money years down the line, and should therefore be regarded as long-term investments. Ground source heat pumps typically cost $15,000–$40,000 installed, and generally have a payback time of 10–20 years.

How does it work?

Geothermal energy can be harnessed from either geothermal power plants or geothermal heat pumps. Geothermal power plants use the heat found a few miles deep into the earth to produce steam for electricity. The power plants are found near reservoirs or surrounding volcanic activity. Wells are drilled 1 or 2 miles deep which will help pump the water under high pressure. When the water reaches the surface, the pressure will stop and that will turn the water into steam.The steam activates a turbine which sets off a generator that fabricates energy. After the steam finishes cooling off in a cooling tower it will condense back into water. The water is brought back into the earth in order for the cycle to begin again.

Geothermal heat pumps are used for heating or cooling homes and can also heat swimming pools. The system is able to transfer heat by transporting refrigerant (a liquid that is constantly going through the phase of being a liquid and then a gas and back again) through pipes right below the earth's surface where the temperature is a constant 50-60 degrees. In the winter or during cold weather, the water will heat up as it travels through the pipe that is underground. When it gets back up to the ground, the warmed water powers heat into the building. When the refrigerant returns to normal temperature, it is transferred back under the ground. During the summer or especially warm weather, the system will run in reverse where the water cools down the building and then is pumped underground where the heat extracted from the building is released to the ground around the pipes.

How is it currently being used?

As of right now, geothermal energy is not used in transit. However there are different ways it’s incorporated into daily life. As mentioned before, geothermal energy is used to provide heat into buildings and homes. Recently, geothermal energy has been used to produce electricity. There are also many people who believe in the healing properties of hot mineral springs, which is a direct use of the energy. 

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How could it be integrated into transit?

To harvest geothermal energy, steam wells are drilled into known geothermal reservoirs where hot geothermal fluid flows to the power plant. The pressure and heat allows it to expand creating rotational or mechanical energy to turn blades. This is then used to turn magnets to create an electric current inside a coil. This electrical energy is then sent outside the plant where the voltage is increased and it can be sent over power lines for multiple uses.

There are many known ways that this energy source can be used including power lines (electricity) or heating buildings. Other ways that we could use this energy in transit would be using the heat generated to de-ice bridges, train tracks or runways. This would save time and money for the people that spend time making these modes of transportation available quicker during the winter months.

In theory, you could use geothermal energy for most things in life. In Iceland, where 25% of their energy production comes from geo-thermal energy, they are planning on using geothermal energy to fuel cars. Since geothermal plants emit a lot of carbon dioxide that isn’t mixed with other chemicals like at coal plants, they can use that recycled carbon dioxide to make methanol. Burning this gas doesn’t emit carbon monoxide or other chemicals like regular gas does. Methanol can be harvested from other sources as well and is becoming a very versatile green source of energy.

Sources

https://www.enelgreenpower.com/learning-hub/renewable-energies/geothermal-energy/advantages 

https://www.solarreviews.com/blog/geothermal-energy-pros-and-cons

https://archive.epa.gov/climatechange/kids/solutions/technologies/geothermal.html

https://www.energy.gov/eere/geothermal/how-geothermal-power-plant-works-simple-text-version

https://www.fastcompany.com/3023455/the-cars-in-iceland-will-be-powered-by-volcano