Non-conventional sources of energy - class-IX

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

The sun is the ultimate source of almost all kinds of energy on earth,

either directly or indirectly.
Directly sun gives us solar power and is perfect non-conventional energy source.
Moreover, Fossil fuels (coal, oil and gas) are the

transformed forms of plants (and animals) which once lived on the earth

and grew capturing the energy of the sun. Biomass is a product of

photosynthesis where the sun has the major role. Hydro-electricity

depends upon the water cycle which again is dependent on solar

radiation. Similarly, wind energy, tidal power, wave power all, in some

way or other, and depend on the sun.

Wind, water, tides all can be used again and again. But, once natural gas is burnt, it can never be used again.

Answer is D.

A non-renewable resource (also called a finite resource) is a resource that does not renew itself at a sufficient rate for sustainable economic extraction in meaningful human time-frames. An example is carbon-based, organically-derived fuel. The original organic material, with the aid of heat and pressure, becomes a fuel such as oil or gas. Earth minerals and metal ores, fossil fuels (such as coal, petroleum, and natural gas), nuclear fuels, and groundwater in certain aquifers are all non-renewable resources.
Natural resources such as coal, petroleum (crude oil) and natural gas take thousands of years to form naturally and cannot be replaced as fast as they are being consumed. Eventually it is considered that fossil-based resources will become too costly to harvest and humanity will need to shift its reliance to other sources of energy. 
Hence, fossil fuels are non-renewable resources.

Cyclical resources are those that can be reused or recycled through natural or human-made processes, making them available for use again after appropriate processing.

Other than dry cells, i.e., the battery cells, all the three devices have been invented to make use of solar energy.

Coal, petroleum and natural gas are conventional source of energy. Nuclear power is a non-conventional source of energy.

Geothermal energy is described from heated ground water.

Geothermal energy is heat from within the Earth. The core and lower part of mantle generates large amount of heat. Deep, super heated water present, can be pumped to surface and used to produce electricity.

A natural source of energy that can provide us energy continuously without being exhausted is called a renewable source of energy.

All the sources of energy are directly or indirectly derived from the ultimate source of energy. i.e. Sun, except for the nuclear energy. Nuclear energy is derived from the molecules of the radioactive elements.

Solar panels are ideal for remote areas because they do not require a connection to a centralized power grid. They can generate electricity locally using sunlight, making them a practical solution for sparsely inhabited regions.

Generation of conventional sources of energy produces environmental threat and air pollution. Generation of non-convention sources of energy is a pollution free process.

Wood is a renewable source of energy because it can be replenished by planting new trees. Petroleum, natural gas, and uranium are finite fossil or mineral fuels that cannot be replaced on a human timescale.

Energy that can be renewed or replenished over a period of time is called renewable energy. E.g. wind energy, solar energy etc.

Sources of energy that are inexhaustible and produced continuously in nature are generally classified as non-conventional or renewable sources. Conventional sources like coal and petroleum are finite and exhaustible.

Solar energy can be converted into electrical energy using photovoltaic cells, heat energy using solar thermal collectors, and mechanical energy through various solar-powered engines or systems.

Bio-ethanol, bio-diesel, and animal fats are recognized forms of biofuels. Bio-petrol is not a standard term or a common biofuel category.

A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter. Biofuels can be derived directly from plants, or indirectly from agricultural, commercial, domestic, and/or industrial wastes. Renewable biofuels generally involve contemporary carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis. Other renewable biofuels are made through the use or conversion of biomass (referring to recently living organisms, most often referring to plants or plant-derived materials). This biomass can be converted to convenient energy-containing substances in three different ways: thermal conversion, chemical conversion, and biochemical conversion. This biomass conversion can result in fuel in solid, liquid, or gas form. This new biomass can also be used directly for biofuels.

Tidal power, also called tidal energy, is a form of hydropower that converts the energy obtained from tides into useful forms of power, mainly electricity.

Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials

Non-conventional energy sources, such as solar or wind, involve converting natural energy flows into usable forms like electricity. They are not created from nothing but are transduced from existing natural energy forms.

 Natural resources like wind, tides, solar, biomass, etc generate energy which is known as "Non-conventional resources“. These are pollution free ,renewable,inexhaustible  and hence we can use these to produce a clean form of energy without any wastage.

Lignite, natural gas, and coal are all fossil fuels formed over millions of years. The Sun is a primary, renewable, and non-fossil source of energy, making it the odd one out.