S.No. Description Marks
Q1 DescribevariousGeothermal EnergyResources. 2
A-1 Refer to class notes.
Q2 Whyisgeothermalconsideredarenewable energyresource? 2
Because its source is the almost unlimited amount of heat generated by the Earth's
A-2 core. Even in geothermal areas dependent on a reservoir of hot water, the volume
taken out can be reinjected, making it a sustainable energy source.
Q3 WritethechemicalreactiontakesplaceinAlkalineFuelCell. 2
Anode: 2H2 (g) + 4(OH)- (aq) → 4H2O (l) + 4e-
Cathode: O2 (g) + 2H2O (l)+ 4e- → 4(OH)-(aq)
A-3
Overall: 2H2 (g) + O2 (g) → 2H2O (l)
What are the practical problems / losses associated with MHD power
Q4 10
generation?
MHD generators have difficult problems regarding:
i. Materials, both for the walls and the electrodes. Materials must not melt
or corrode at very high temperatures. Exotic ceramics were developed
for this purpose and must be selected to be compatible with the fuel and
A-4 ionization seed.
ii. Suffers from reverse flow (short circuits) of electrons through the
conducting fluids around the ends of the magnetic field.
iii. Needs very large magnets and this is a major expense.
iv. High friction and heat transfer losses
v. High operating temperature
Describe the various operational and
Q5 environmentalproblemsencounteredin obtainingthegeothermal 10
energy.
A-5 Geothermal resources are either dry steam fields or wet steam fields.
Hydrothermal (dry steam) fields contain non-condensable gases CO2 and small
traces of hydrogen sulphide, ammonia, methane etc. These gases are released from
centrifugal separators and in turbine exhaust of geothermal power plants.
Though the amount of CO2 released is much less compared to conventional power
plants but it adds to the problem of global warming.
H2S in the geothermal fields in excess quantity causes harmful effects on the
bearings and electrical Equipment of the plant. Therefore, it is necessary to
trap H2S and burned with air to produce SO2which is controlled by scrubbing of
flue gases with lime or catalytic conversion technologies.
SO2 if not treated before released to atmosphere may have adverse effect on
agriculture production and aquatic life caused by acid rain.
The wet geothermal fields contain poisonous and toxic, material like mercury,
arsenic and salt content of brine.
These dissolved solids may be as high as 20% to 30%.
The liquid waste causes environment problems can be resolved by re – injecting
the use water waste deep into the ground. Thus, the pollutants in such geothermal
plants are almost eliminated.
The heat energy of turbine exhaust steam is rejected to atmosphere in cooling
towers. It causes increase in moisture in atmosphere.
Q1 DescribevariousGeothermal EnergyResources. 2
A-1 Refer to class notes.
Q2 Whyisgeothermalconsideredarenewable energyresource? 2
Because its source is the almost unlimited amount of heat generated by the Earth's
A-2 core. Even in geothermal areas dependent on a reservoir of hot water, the volume
taken out can be reinjected, making it a sustainable energy source.
Q3 WritethechemicalreactiontakesplaceinAlkalineFuelCell. 2
Anode: 2H2 (g) + 4(OH)- (aq) → 4H2O (l) + 4e-
Cathode: O2 (g) + 2H2O (l)+ 4e- → 4(OH)-(aq)
A-3
Overall: 2H2 (g) + O2 (g) → 2H2O (l)
What are the practical problems / losses associated with MHD power
Q4 10
generation?
MHD generators have difficult problems regarding:
i. Materials, both for the walls and the electrodes. Materials must not melt
or corrode at very high temperatures. Exotic ceramics were developed
for this purpose and must be selected to be compatible with the fuel and
A-4 ionization seed.
ii. Suffers from reverse flow (short circuits) of electrons through the
conducting fluids around the ends of the magnetic field.
iii. Needs very large magnets and this is a major expense.
iv. High friction and heat transfer losses
v. High operating temperature
Describe the various operational and
Q5 environmentalproblemsencounteredin obtainingthegeothermal 10
energy.
A-5 Geothermal resources are either dry steam fields or wet steam fields.
Hydrothermal (dry steam) fields contain non-condensable gases CO2 and small
traces of hydrogen sulphide, ammonia, methane etc. These gases are released from
centrifugal separators and in turbine exhaust of geothermal power plants.
Though the amount of CO2 released is much less compared to conventional power
plants but it adds to the problem of global warming.
H2S in the geothermal fields in excess quantity causes harmful effects on the
bearings and electrical Equipment of the plant. Therefore, it is necessary to
trap H2S and burned with air to produce SO2which is controlled by scrubbing of
flue gases with lime or catalytic conversion technologies.
SO2 if not treated before released to atmosphere may have adverse effect on
agriculture production and aquatic life caused by acid rain.
The wet geothermal fields contain poisonous and toxic, material like mercury,
arsenic and salt content of brine.
These dissolved solids may be as high as 20% to 30%.
The liquid waste causes environment problems can be resolved by re – injecting
the use water waste deep into the ground. Thus, the pollutants in such geothermal
plants are almost eliminated.
The heat energy of turbine exhaust steam is rejected to atmosphere in cooling
towers. It causes increase in moisture in atmosphere.
