What is Geothermal Energy?
Believe it or not the deeper you go into the Earth the hotter it gets. Part of the heat is left over from the creation of the Earth, which started off as a hot cloud of gas and dust and has been cooling over time. As we have learned in class the outer layers of the Earth have cooled most quickly, forming the crust; heat from the core continues to radiate outwards along what is known as a Geothermal gradient Heat flows from hot to cold – the inner core of the Earth is hotter than 5,000°C, while the surface is generally less than 30°C and outer space is close to absolute zero.
Geothermal energy has an even more important source: radioactive decay. Radioactive elements break down into more stable atoms by emitting radiation and nuclear particles. Naturally occurring uranium, thorium and potassium decay over very long periods of time. Radiation is emitted as they decay and heats the rocks in which they sit, adding to the geothermal resource. This creation of new heat by radioactive decay and the continuous flow of heat towards the Earth’s surface are reasons geothermal energy is considered a renewable resource.
Benefits of Geothermal Energy
Abundant and renewable: It is abundant and it is renewable. While the heat of a hot rock reservoir tapped for its energy can be depleted, it will eventually be replaced.
Environmentally friendly: In almost every aspect of its development, geothermal energy is environmentally benign. Once the plant is established, geothermal energy production generates few greenhouse gas emissions or other forms of pollution.
Price: Other renewable energy solutions are only available when the sun shines or the wind blows. Geothermal energy, in contrast, is available 24 hours a day and can therefore provide continuous power.
Technical challenges: One determent to Geothermal power is that the techniques for tapping hot rock resources are only now being developed. There has been recent test sites showing encouraging results, but how the properties of hot rock reservoirs might change over time is unknown.
Start-up Costs: Given the lack of existing technologies and the costs of drilling, the start-up costs of hot rock geothermal operations are very high. Geothermal ventures still require investors willing to risk their money in technology that is developing.
Infrastructure: Some of the best-known geothermal resources are a long way from cities or even decent roads. This means very long power transmission lines might need to be built, which would decrease efficiencies and increase costs.
Contaminants: In some systems, the hot geothermal fluids contain dissolved minerals and gases. Some of these might have commercial value, but there might also be a risk of groundwater contamination and the release of greenhouse gases to the atmosphere. However the very small amounts of radioactive substances that occur naturally in rocks are believed to be too low to be of concern.
There are several drawbacks to go with the pros of Geothermal energy however if used along side other forms of renewable energy in the future the Earth will be a healthier place to live, and carbon emissions will eventually be a concern of the past.