GATE Overflow for GATE ESE - Recent questions and answers in Energy and Environment: Energy Sources

GATE ES 2026 | Question: 55

Mon, 23 Feb 2026 13:14:21 +0000

An agricultural land can support energy crops yield to produce $7000$ $\text{L}$ of bioethanol per hectare and energy content of bioethanol is $21 \mathrm{MJ} / \mathrm{L}$. This bioethanol displaces fossil-based petrol.

The $\mathrm{CO}_{2}$ offset potential of land used for growing energy crops as a bioethanol feedstock is $\_\_\_\_$ $\times 10^{6} \mathrm{~g}$ of $\mathrm{CO}_{2}$ /hectare (rounded off to one decimal place).

Consider $\mathrm{CO}_{2}$ footprints of $10$ g and $80$ g of $\mathrm{CO}_{2}$ per $\text{MJ}$ for bioethanol and petrol, respectively.

GATE ES 2025 | Question: 21

Thu, 06 Mar 2025 16:22:00 +0000

Methane hydrates have special crystal structure of water, where methane gas molecules are trapped. Choose the correct option(s) from the following

Methane hydrates exist in abundance near the ocean bed, where the pressure is high enough for their existence.
Methane hydrates exist in abundance in the polar regions, where the temperature is low enough for their existence.
Methane hydrates can be a huge source of energy, but can accelerate global warming considerably if the entrapped methane is released to the atmosphere.
Methane hydrates can be a huge source of energy, but difficult to exploit commercially.

GATE ES 2024 | Question: 54

Mon, 19 Feb 2024 10:24:04 +0000

In a region, total annual consumption of gasoline is 30.6 million tons. The land required for growing sugarcane to produce enough bioethanol to replace the gasoline completely is __________ $\mathrm{km}^{2}$ $\text{(an integer value)}$.

Ethanol energy equivalent is $67 \%$ of gasoline, gasoline density is $850 \mathrm{~kg} / \mathrm{m}^{3}$, yield of bioethanol produced from sugarcane per hectare of land is $3750 \mathrm{~L}$, and $1 \mathrm{~km}^{2}=100$ hectares.

GATE ES 2022 | Question: 55

Fri, 17 Feb 2023 07:05:32 +0000

Figure below gives the heat inflow into the furnace of a waste-to-energy plant along with the heat outflows from the furnace.

Assume: (i) total heat loss equal to $3 \%$ of heat released while burning waste, (ii) sensible heat of the waste is negligible, (iii) complete burning of the waste is ensured. If the waste feed rate into this plant is $70 \mathrm{~kg} / \mathrm{h}$, the heat content of the waste $\text{(in kcal kg, rounded off to one decimal place)}$ is