Energy and Clean Technology

Pumped-storage hydropower (PSH) is used for long-duration energy storage. It works by pumping water to a higher reservoir during low electricity demand and releasing it to generate power during peak demand. This process helps balance the grid supply and demand, making PSH an effective tool for energy storage over extended periods.

Thus, the correct answer is C.

Distributed Energy Resources (DERs) are small-scale units of power generation or storage that are situated closer to the end-users. Let's analyze each option:

* Battery storage: These store energy and can be deployed within the distribution network or at the consumer end, making them DERs.

* Biomass generators: These can be small-scale and located near the biomass source, making them suitable for distributed generation.

* Fuel cells: Similar to biomass generators, fuel cells can be deployed in a decentralized manner, qualifying as DERs.

* Rooftop solar photovoltaic units: These are a classic example of DERs, generating power at the point of consumption.

_Therefore, all four options are considered Distributed Energy Resources._

* Statement 1: Incorrect. RTGs (Radioisotope Thermoelectric Generators) are not miniature fission reactors. Fission reactors use nuclear fission, a process of splitting atoms to release a tremendous amount of energy. RTGs, on the other hand, utilize the natural radioactive decay of isotopes to generate heat, which is then converted to electricity through a process called thermoelectricity.

* Statement 2: Correct. RTGs are indeed a reliable power source for spacecraft, especially those venturing far from the sun where solar panels become ineffective. They provide consistent, low-level electric power for extended periods, making them ideal for probes, satellites, and rovers in deep space.

* Statement 3: Correct. Plutonium-238 is a common isotope used in RTGs due to its long half-life (the time it takes for half of the material to decay) and its ability to generate a steady heat output from its decay process. While it can be a byproduct of weapons development, there are also alternative ways to produce Plutonium-238 specifically for peaceful applications like RTGs.

In India, nuclear reactors are categorized into civilian and strategic (military) facilities as part of the 2005 Indo-US Civil Nuclear Deal. Reactors that rely on imported uranium are mandatory participants in the International Atomic Energy Agency (IAEA) safeguards to ensure the fuel is used strictly for peaceful, civilian purposes. In contrast, reactors using domestic uranium supplies are kept outside these safeguards to allow India the flexibility to use them for its strategic nuclear weapons program.

Statement 1 is incorrect. The production of algae-based biofuels is not limited to seas only. It can be done on land, saline water, or wastewater.

Statement 2 is correct. Setting up and engineering the algae-based biofuel production does require a high level of expertise/technology, which might be a limitation for developing countries.

Statement 3 is also correct. Economically viable production of algae-based biofuels does necessitate the setting up of large-scale facilities, which may raise ecological and social concerns.


India is a key participant in the International Thermonuclear Experimental Reactor (ITER), a global nuclear fusion research and engineering megaproject. ITER is set to become the world's largest magnetic confinement plasma physics experiment, aiming to demonstrate the feasibility of fusion as a large-scale, sustainable energy source.


India's involvement in ITER provides technological expertise, research collaboration, and industrial capabilities, which can significantly contribute to its future efforts in developing nuclear fusion reactors for commercial power generation. By participating in this international project, India gains access to cutting-edge advancements in fusion technology, potentially paving the way for its own fusion-based energy infrastructure. Hence, the correct answer is option D.

Statement 1 is correct. Bagasse: This fibrous residue left after sugarcane juice extraction is a valuable biomass fuel. It can be burned to generate electricity or heat, often powering the sugar mills themselves.

Statement 2 is incorrect. Synthetic Fertilizers: Molasses don't directly contribute to the production of synthetic chemical fertilizers. These fertilizers are typically manufactured using chemical processes involving elements like nitrogen, phosphorus, and potassium.

Statement 3 is correct. Molasses: While molasses isn't directly used to produce synthetic fertilizers, it can be fermented to create ethanol, a biofuel. Ethanol can be used as a transportation fuel or blended with gasoline.

Thus, statements 1 & 3 are correct while statement 2 is wrong.