Geothermal energy is literally the heat of the earth. This energy source uses the heat that is present below the surface of the earth for heating or for power applications.
Globally, about 16 GW of geothermal power generation capacity was available at the end of 2020, present mainly in about ten countries that have significant geothermal activities required for geothermal power plants - USA, Indonesia, Philippines, Turkey and New Zealand make up the top 5 in installed capacity. Geothermal heating through geothermal heat pumps is being used by many more countries worldwide.
First geothermal power generation and geothermal heating are fairly well-established technologies. The second and subsequent generations of geothermal power generation - using concepts such as enhanced geothermal and submarine geothermal - are still not fully commercialized.
Geothermal power generation requires the presence of hot springs or regions that have significant geothermal activity. As a result, large-scale geothermal power generation is likely to be restricted to a few countries for the 2020-2030 period. Geothermal heating however can become far more widespread, and for the following reason. The layer below the earth’s surface is at a constant temperature throughout the year - thus it is hotter than the surface during winter and colder during summer. Geothermal heating (and cooling) is thus feasible for most regions in the world.
Geothermal heating systems have few disadvantages except for the digging up work needed in the vicinity of implementation. In addition to the lack of exploitable sites, geothermal power plants have however faced other challenges in the form of the environmental hazards such as gaseous emissions, and contamination of aquifers in the vicinity. The next gen geothermal plants use processes for fracturing rocks (similar to processes used for shale oil or gas) and thus carry environmental and geological hazards some of which have not been fully understood yet.
Innovations in geothermal (both power and heat) for the 2020-2030 period will likely be in the domains of heat well design, innovations in various geothermal drilling and power generation equipment, ground water source geothermal heating, and use of digital and data driven systems for geothermal power generation optimization. During this period, the development of binary cycle power plants and improvements in drilling and extraction technology may enable enhanced geothermal systems over a much greater geographical range. Enhanced geothermal demonstration projects are operational in countries like Germany, France, Australia and the US.
Geothermal power currently has a relatively low installed capacity compared to those of solar power and wind power - about 15 GW at the end of 2020. Given that geothermal power plants can only be installed at selective locations, the total potential for geothermal power generation with the conventional technologies is estimated to be only about 80 GW. This potential could increase significantly if developers are able to tap into high geothermal heat at many other locations worldwide using next generation technologies. Estimates however suggest that geothermal has the potential to reach about 1400 TWh of electricity by 2050, from about 120 TWh they currently provide.
Of equal interest - or perhaps is geothermal heating, using heat pumps. From the current energy generation of about 280 TWh per year, it is expected to increase to 1600 TWh per year by 2050 under growth conditions.
With the above 2050 estimates as benchmarks, geothermal heat and power can save a total of 1.2 billion CO2 emissions per annum.
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