Nuclear fission is a nuclear reaction where nucleus of a heavy atom splits into two lighter nuclei. In this process, some nuclear mass gets destroyed and converted into energy. According to Einstein's mass-energy relation, when a mass is destroyed, it gets converted into a huge amount of energy. It is the destruction of mass that is responsible for the release of unusually large energies in nuclear fission reactions.

Biogas is considered as an ideal fuel because it 
Has a high calorific value
Produces no smoke on burning
Burns smoothly without any explosion
Leaves no residue on combustion

a) The construction of wind energy farm is costly.
b) The continuous whistling and whirling is irritating.
c) The location of wind energy farms affects the route of migratory birds.
d) It can be located only in vast open areas where the minimum velocity for a windmill to function is 15 km/hr.

a) It is eco-friendly.
b) It is found abundantly.
c) It converts visible as well as IR rays into electricity.

For this purpose ocean thermal energy conversion (OTEC) power plants are used. To use this plant a difference of 200C or more between the temperature of surface waters and water at depths of 1000 metres is required. In one of Ocean Thermal Energy Conversion system, the warm surface water is used to boil low boiling liquid like Ammonia or a chlorofluorocarbon. The vapors of the liquid are then sent to move the turbines of generator. The cold water from the depths is used to cool the vapor escaped from the turbines and converted into liquid to be used again.

It is one of those sources of energy that do not come directly or indirectly from the solar energy.

Because of growing population, the energy demand is rising. We need to find an alternate source of energy which renewable and environment friendly.

A good source of energy should be renewable and environment friendly.

Advantages of Solar Cooker
a) They are environment friendly.
b) Use of a solar cooker does not involve recurring expenses on fuel.
Disadvantages of Solar Cooker.
a) Solar cooker is very slow.
b) Solar cooker can work only during summer months and is useless during winters and on cloudy days.
c) Solar cooker can be useful at those places which receive plenty of sunshine. This is useless in colder climates.

(i) Solar constant of sun is 1.4 kW/m².
(ii) Concave mirrors are used in box type solar cookers.
(iii) It is difficult to use hydrogen as a source of energy because it has not been possible to control nuclear fusion reaction. Thus, it has not yet been possible to use energy generated from fusion reaction for anything constructive.
(iv) Fossil fuels are classified as non-renewable sources of energy because it takes a long time for them to replenish naturally. It takes millions of years for fossil fuels to replenish. With the rate at which humans are using them, they will get exhausted in the next hundred years. Thus, fossil fuels are termed as non-renewable source of energy. 

i) All fossil are the remains of the prehistoric plants and animals. Th energy of the fossil fuels is in fact that solar energy which was trapped by natural processes a long time ago.
ii) Solar energy also appears in the form of energy of water flowing in rivers as is obvious from the water cycle in nature. It is this energy which generates in hydroelectric power plants.
iii) Biomass energy is also the solar energy absorbed by the plans which convert it into chemical energy through photosynthesis.
iv) Human and animals use bioenergy to carry out their life activities.
v) Solar energy is one of the main factors responsible for the movement of air in the atmosphere leading to wind energy.
vi) Solar energy is used directly in solar.

In a process called nuclear fission, the nucleus of a heavy atom (such as uranium, plutonium or thorium), when bombarded with low-energy neutrons, can be split into lighter nuclei with a release of tremendous amount of energy if the mass of the original nucleus is just a little more than the sum of the masses of the individual products.

The released energy can be used to produce steam and further generate electricity. The major hazard of nuclear power generation is the storage and disposal of spent or used fuels. Improper nuclear-waste storage and disposal result in environmental contamination. Further, there is a risk of accidental leakage of nuclear radiation. The high cost of installation of a nuclear power plant, high risk of environmental contamination and limited availability of uranium makes large-scale use of nuclear energy prohibitive. The only viable way to dispose off radioactive waste is to bury it deep underground. "The nuclear waste also should be guarded against any misuse.