Shankar IAS Test: Renewable Energy - UPSC MCQ

Renewable energy comprises of

• Solar energy - energy generated from the sun

• Hydel energy - energy derived from water

• Biomass – energy from firewood, animal dung, biodegradable waste, and crop residues when burnt.

• Geothermal energy- energy from hot, dry rocks, magma, hot water springs, natural geysers, etc.

There are two ways we can produce electricity from the sunlight:

• Photovoltaic Electricity – uses photovoltaic cells that absorb the direct sunlight to generate electricity

• Solar-Thermal Electricity – uses a solar collector that has a mirrored surface which reflects the sunlight onto a receiver that heats a liquid is heated up liquid is used to make steam that produces electricity

The correct answer is:

        3. 2 only

Explanation:

1. The first statement is incorrect. Onshore wind farms operate on land, but the wind on land is generally not as strong as the wind over the sea. Offshore wind farms, which are located in bodies of water, tend to have stronger and more consistent wind patterns.

2. The second statement is correct. The turbines of onshore wind farms are indeed less expensive and easier to set up, maintain, and operate compared to offshore turbines. Offshore wind farms involve more complex and costly logistics due to their location in water bodies, requiring specialized equipment and vessels for installation and maintenance.

Air density- Heavier air exerts more lift on a rotor. Air density is a function of altitude, temperature, and pressure. High altitude locations have low air pressure and lighter air, so they are less productive turbine locations. The dense, heavy air near sea level drives rotors faster and thus relatively more effectively.

• Hydraulic power can be captured when water flows down from a higher level to a lower level, which is then used to turn the turbine, thereby converting the kinetic energy of water into mechanical energy to drive the generator.

• Hydropower is the cheapest and cleanest energy source, but there are many environmental and social issues associated with big dams, as seen in projects like Tehri, Narmada, etc.

• Wave energy: Waves result from the wind's interaction with the surface of the sea and represent a transfer of energy from the wind to the sea. The first wave energy project with a capacity of 150MW has been set up at Vizhinjam near Trivandrum.

• Tidal energy can be extracted from tides by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines to generate electricity. A major tidal wave power project costing Rs.5000 crores is proposed to be set up in the Hanthal Creek in the Gulf of Kutch in Gujarat.

- Statement 1 is incorrect: Pyrolysis/Gasification involves heating waste in low or no oxygen conditions, not burning it in excess oxygen.
- Statement 2 is about combustion, not pyrolysis/gasification, and doesn't apply here.
- Statement 3 is correct: In pyrolysis/gasification processes, the generated steam can indeed be used in steam turbines to produce power.
- Therefore, only Statement 3 is correct, making the correct answer B: 3 only.

• Geothermal systems can be found in regions with a normal or slightly above average geothermal gradient (gradual temperature change is known as the geothermal gradient), which expresses the increase in temperature with depth in the earth's crust.

• The average geothermal gradient is about 2.5-3 °C/100 m.) and especially in regions around plate margins where the geothermal gradients may be significantly higher than the average value.

• The most common current way of capturing geothermal sources' energy is to tap into naturally occurring "hydrothermal convection" systems where cooler water seeps into the earth's crust, is heated up, and rises to the surface.

• When heated water is forced to the surface, it is relatively easy to capture that steam and drive electric generators. Potential in India India has a potential for producing around 10,600 MW of power from geothermal resources.

• Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly and efficiently into electricity (D.C.) and heat, thus doing away with combustion.

• The most suitable fuel for such cells is hydrogen or a mixture of compounds containing hydrogen.

• A fuel cell consists of an electrolyte sandwiched between two electrodes.

• Oxygen passes over one electrode and hydrogen over the other, and they react electrochemically to generate electricity, water, and heat.

The conventional sources of energy are the fossil fuels. It took millions of years for the formation of fossil fuels; hence they are limited and non-renewable. Fossils are remains of organisms that lived in the past and fossil fuels are plants that got buried under earth that became rock over years. Fossil fuels have to be unearthed from mines.