CBSE Class 10 - Science - CH 14 Sources of Energy (Important Differences) (#cbseNotes)

Sources of Energy (Important Differences) 

Fossil Fuels Energy vs Solar Energy

	Fossil Fuels Energy	Solar Energy
1.	Fossil energy can be used day or night.	Can be used in day time. We need to store its energy to use it at night.
2.	The stock of fossil energy is limited. e.g. coals will last for next 200 years.	Sun’s energy is unlimited.
3.	Fossil energy is non-renewable. It takes millions of year to produce fossil fuel.	Solar energy is renewable source of energy.
4.	Give pollution.	Pollution Less
5.	Fossil fuels release energy when they are burnt in air.	Solar radiation carry packets of energy due to fusion reaction in the sun.

Bio-Mass vs Hydroelectricity

	Bio-Mass	Hydroelectricity
1.	Energy is produced by anaerobic breakdown of plants and animal wastes by microbes.	Potential Energy of Water stored in reservoir or its kinetic energy (high flow of water) is converted to usable form of energy.
2.	Requires small setup. Low setup cost.	Requires large setup with high costs.
3.	Bio Mass generates methane and other gases which causes global warming and pollution.	Hydro dams submerges large habitat which rots and gives green houses gases causing global warming.
4.	Apart from air pollution no other major threat to ecosystem.	Big reservoirs in hilly regions increases the risk of earthquakes.
5.	Saves landfill space as bio mass is converted into energy.	Hydroelectric plants saves costs of consuming fossil fuels.

Nuclear Fission vs Nuclear Fusion

No.	Nuclear Fission	Nuclear Fusion
1.	Nucleus of a heavy element breaks into lighter nuclei along with enormous amount of energy.	Two or more lighter nuclei join together and form a heavy nucleus plus release of energy.
2.	It is a chain reaction i.e. fission of one nucleus leads to product of neutrons which causes heavy nuclei to disintegrate.	It is not a chain reaction.
3.	Requires thermal neutrons which splits the nucleus and does not require high temperature initially.	Requires high temperature of 10⁶ K range to initiate fusion.
4.	Practically this nuclear feasible in a reactor.	Practically not feasible in a reactor.
5.	Controlled nuclear reaction in a reactor.	Uncontrolled nuclear reaction has been achieved in weapons like hydrogen bomb.
6.	Fission waste is radioactive, long lived and threatens natural environment. Its disposal is a big challenge.	Fusion radioactive waste is short lived.