# Energy Engineering Questions and Answers – Geothermal Energy

This set of Energy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Geothermal Energy”.

1. The process of producing energy by utilizing heat trapped inside the earth surface is called _________
a) Hydrothermal energy
b) Geo-Thermal energy
c) Solar energy
d) Wave energy

Explanation: The process of producing energy by utilizing heat trapped inside the earth surface is called Geo thermal energy. Energy present as heat in the earth’s crust. The more readily accessible heat in the upper most (10 km) or so, of the crust constitutes a potentially useful and almost inexhaustible source of energy.

2. How much is the average temperature at depth of 10 km of earth surface?
a) 200oC
b) 900oC
c) 650oC
d) 20oC

Explanation: The heat is apparent from the increase in temperature of the earth with increasing depth below the surface. Although higher and lower temperature occurs, the average temperature at depth of 10 km is about 200oC.

3. What is hot molten rock called?
a) Lava
b) Magma
c) Igneous rocks
d) Volcano

Explanation: Magma is a mixture of molten or semi-molten rock, volatiles and solid that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles.

4. How many kinds of Geo thermal steams are there?
a) 2
b) 3
c) 4
d) 5

Explanation: There are two kinds of geo thermal steams, the one that originates from the magma is called magmatic steam and that from ground water heated by magma is called meteoritic steam. The latter is the largest source of geothermal steam.

5. What does EGS stand for in geothermal energy?
a) Engraved Geothermal systems
b) Enhanced geothermal system
c) Exhaust gas system
d) Engineered geo physical system

Explanation: The development of a geothermal system where hydraulic fracturing of the system can allow the production at a commercial level. EGS’s are engineered reservoirs created where there is geothermal energy but a lack of permeability. Fluid is injected into the earth‘s surface which causes pre-existing fractures to open again, creating permeability. Nationwide potential with engineered reservoirs 6-km to 8-km deep.

6. Who invented first geothermal plant?
b) Piero Ginori Conti
c) Enrico Fermi
d) Guglielmo Marconi

Explanation: In 1904, Italian scientist Piero Ginori Conti invented the first geothermal electric power plant in which steam was used to generate the power. On 4 July 1904, at Larderello, Piero Ginori Conti powered five bulbs from a dynamo driven by a reciprocating steam engine using geothermal energy.

7. A geothermal solution containing appreciable amounts of sodium chloride or other salts is called as __________
a) Fluids
b) Brine
c) Solvent
d) Magma

Explanation: Brine is a high-concentration solution of salt (usually sodium chloride) in water. In different contexts, brine may refer to salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of solutions used for brining foods) up to about 26% (a typical saturated solution, depending on temperature).

8. Earth’s outer layer rock is called as __________
a) Mantle
b) Crust
c) Outer core
d) Asthenosphere

Explanation: Earth’s crust is Earth’s hard outer layer. It is less than 1% of Earth’s volume. The crust is made up of different types of rocks: igneous, metamorphic, and sedimentary rocks. Crust is also called as lithosphere.

9. The hole on earth’s surface from where the steam from the earth comes out is called as ________
a) Gash
b) Mud pot
c) Void
d) Fumarole

Explanation: A fumarole is an opening in a planet’s crust, often in areas surrounding volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. The steam forms when superheated water condenses as its pressure drops when it emerges from the ground.

10. A spring that shoots jets of hot water and steam into the air is called as _______
a) Mine hole
b) Geyser
c) Hot spring
d) Mud pot

Explanation: Geysers are temporary geological features. Geysers are generally associated with volcanic areas. As the water boils, the resulting pressure forces a superheated column of steam and water to the surface through the geyser’s internal plumbing.

11. Which kind geothermal plant is most common type?
a) Dry steam
b) Flash
c) Binary
d) Wet steam

Explanation: Flash Steam Power Plants are the most common form of geothermal power plant. The hot water is pumped under great pressure to the surface. When it reaches the surface the pressure is reduced and as a result some of the water changes to steam. This produces a ‘blast’ of steam. The cooled water is returned to the reservoir to be heated by geothermal rocks again.

12. How much is the efficiency of geothermal plant?
a) 28%
b) 15%
c) 42%
d) 30%

Explanation: Geothermal power plants have lower efficiency relative to other thermal power plants, such as coal, natural gas, oil, and nuclear power stations. It is commonly assumed that only 15% of the energy from the produced geothermal fluid can be converted to electricity.

Sanfoundry Global Education & Learning Series – Energy Engineering.

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