Geothermal energy is renewable energy source that is practically inexhaustible source of energy. We are talking here about the thermal energy of our planet that is being constantly replenished by the radioactive decay of the minerals and as such it cannot be exhausted.
So what we have here is an environmentally friendly energy source with enormous potential and yet only a tiny fraction of it is being used. Worldwide, 12,635 megawatts (MW) of geothermal power is online in 2015, with current estimates predicting around 21,500 MW in 2020. Given total geothermal potential these are really small numbers, and not something global geothermal industry can be proud of. For example, U.S. geothermal power plants currently provide only around 0.4% of total U.S. electricity generation.
The Earth's geothermal resources are more than enough to supply entire humanity's energy needs but sadly not today, and definitely not with today's technologies.
What is the main problem with currently available geothermal technologies? The first thing is the reach of these technologies which is very limited as only areas near the tectonic boundaries offer economic viability of new geothermal projects.
High capital costs are usually main stumbling block for new geothermal power projects. According to 2010 data the estimated costs of geothermal power plant construction and well drilling are at €2-5 million per generated MW of electricity.
Geothermal drilling is also one of the main reasons why world doesn't use more geothermal energy. Geothermal drilling is significantly more complicated than oil drilling because geothermal drilling has to go through igneous and metamorphic rocks, which are harder and lot more fractured compared to sedimentary rocks through which most oil wells are drilled. Also, lot higher temperatures are involved compared to those associated with oil wells.
What global geothermal energy industry needs is a major technological development. This, however, will be difficult to achieve given the fact that geothermal drillers create only a small number of new geothermal wells each year so there's not a lot to build and learn from.
Some technologies, like for instance Enhanced Geothermal System (EGS) technology offer hope that harnessing geothermal energy could spread to much wider area in years to come. The working principle of this technology is to create a subsurface fracture system in which water is added through injection wells and then is heated by contact with the rock and returns to the surface through production wells, as in naturally occurring hydrothermal systems.
To conclude, the technologies to harness geothermal energy will have to significantly improve in order for geothermal energy to become more used on global scale. Less expensive drilling, wider area to harness the resource from and reduced capital costs – these are all the solutions on which global geothermal energy industry should build its future progress.
As already stated above geothermal energy has practically unlimited potential, and could theoretically power our entire planet. Finding the adequate technology to exploit this potential is essential for geothermal energy to become one of the most important energy sources in years to come.