Page 7 - Environmental_Green Technologies

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- Geothermal – Geothermal energy takes its origin within the sub-surface of the earth carried by water
and/or steam to the Earth’s surface, usually located to nearby tectonically active regions. Regarding the
usage of this type of energy, it depends on it characteristics. It can be used for cooling and heating
purposes or be harnessed to generate clean electricity. One of the main advantages is that the geothermal
power sources do not depend on weather conditions with very high capacity factors. There are different
geothermal technologies for different applications with distinct levels of maturity. Geothermal technologies
for direct uses are the mature ones applied widely like for district heating, greenhouses and other
applications. Another mature technology is the one for electricity generation from hydrothermal reservoirs
with naturally high permeability, operating from 1913. Furthermore, many of the geothermal power plants
are flash or dry steam plants. The medium temperature fields are used more for electricity generation
and new technologies, still at demonstration stages, like the Enhanced Geothermal Systems (EGS) (IRENA,
2019).

In order to enhance and promote dialogue and knowledge about geothermal energy and heat generation,
the coalition Global Geothermal Alliance (GGA) was created in 1988, claiming and promoting this source of
energy among governments and other stakeholders (IRENA, 2019).

- Hydropower – Hydropower or hydroelectricity, one of the first sources in the generation of electricity,
defines the energy derived from flowing water into electricity. It is a renewable energy source because it is
a type of energy depending on the cycle of the water that constantly renewed by the sun. For the produc-
tion of hydropower, the amount of precipitations determines the amount of water available for producing
hydropower (Eia, 2019).

The hydropower generated by the flowing water is using this power to drive turbines. The hydropow-
er plans are with dams and reservoirs, or without. The first, the dams store water in order to meet peal
demands or for concrete electricity generation purposes; and the second one, without dams, it is more
environmentally friendly option in which it operated without interfering the flows of a river. For instance,
Norway’s 99% electricity comes from hydropower (IRENA, 2019).