PHYSICS HOLIDAY HOMEWORK

ONAlternate Sources

of Energy

What is Energy?Different sources of energyExplanation for each sourceWhich is the best source of energy?

Conclusion

What Is Energy?

The scientific definition of energy is that “Energy is an indirectly observed physical quantity which is the ability of body or a system to do work.”  On a logical point of view, we can understand energy as something which enables us to do work. If we have energy then work can be done. Energy is conserved in systems, meaning that it can neither be created nor destroyed but is inter-convertible into its different forms. It comes from many sources and in many forms. The forms of energy are classified in two general categories: potential and kinetic.Potential energy is energy stored in an object. Chemical, mechanical, nuclear, gravitational, and electrical are all stored energy. Kinetic energy does the work. Light, heat, motion, and sound are examples of kinetic energy.

Different Sources of

Energy

There are two types of energy sources, Renewable and Non-Renewable sources. Renewable energy sources are sources that can be replenished or which are available naturally in excess. Non-Renewable energy sources are limited in their availability. Renewable energy sources are more ‘Environment-Friendly’ as they do not cause any natural imbalances. Whereas acquisition and usage of Non-Renewable energy sources causes disruption and disturbs the balance of environment. List of Energy sources according to their types are• Non-Renewable Energy sources:Fossil FuelNuclear Energy• Renewable Energy sources are: Air (Wind Energy)Water (Hydro-Electric Energy)Sun (Solar Energy)Biogas (Alternative fuels) etc.

FOSSIL FUEL

Fossil Fuels:Fossil Fuels, as the name suggests are formed by fossils which are compressed by the pressure of the earth’s crust under the duration of thousands of years and so they cannot be replaced as soon as they have been consumed. When coal is burnt, it releases a lot of energy which is used to convert water to steam and the steam is made to run turbines to produce electricity. Petroleum finds it place in the combustion chambers of an internal combustion engine to power various machines. Also the usage of such fossil fuels also promotes emission of harmful greenhouse gases, increasing the volume of global warming.

Nuclear

Energy

Nuclear Energy:

Nuclear energy is harvested from Uranium-238 which is extracted from the sparsely present Uranium ores. The Uranium extracted from these ores is used in nuclear reactors, the heat from which produces steam which runs turbines to produce electricity. Uranium is mined only 19 countries and comprises only 6% contribution of energy in the world. However, a downside of nuclear energy is radioactive waste. The mistreatment of radioactive waste leads to devastating consequences which include cancer. Even damage to the reaction chambers by either natural or man made disasters causes radioactive contamination in the surrounding area which will last for a very long period. One such event was seen after the Japanese Tsunami, 2012.

WIND ENERGY• All renewable energy (except tidal and geothermal power),

ultimately comes from the sun

• The earth receives 1.74 x 1017 watts of power (per hour) from the sun

• About one or 2 percent of this energy is converted to wind energy (which is about 50-100 times more than the energy converted to biomass by all plants on earth

• Differential heating of the earth’s surface

and atmosphere induces vertical and horizontal

air currents that are affected by the earth’s

rotation and contours of the land WIND.

~ e.g.: Land Sea Breeze Cycle

• Winds are influenced by the ground surface at altitudes up to 100 meters.

• Wind is slowed by the surface roughness and obstacles.

• When dealing with wind energy, we are concerned with surface winds.

• A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades.

• The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed.

• The kinetic energy of a moving body is proportional to its mass (or weight). The kinetic energy in the wind thus depends on the density of the air, i.e. its mass per unit of volume. In other words, the "heavier" the air, the more energy is received by the turbine.

•Therefore the wind energy is the most important renewable resource on the Earth.

Hydro-Electric Energy

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy, accounting for 16 % of global electricity generation – 3,427 terawatt-hours of electricity production in 2010.

The major advantage of hydroelectricity is elimination of the cost of fuel. The cost of operating a hydroelectric plant is nearly immune to increases in the cost of fossil fuels such as oil, natural gas or coal, and no imports are needed. The average cost of electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatt-hour.

Solar

Energy

Solar energy, radiant light and heat from the sun, is harnessed using a range of ever-evolving technologies such as solar heating, solar photovoltaic, solar thermal electricity, solar architecture and artificial photosynthesis. Solar energy refers primarily to the use of solar radiation for practical ends. However, all renewable energies, other than geothermal and tidal, derive their energy from the sun.Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favourable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies. It is also used in cooking, heating, transportation, agriculture etc.

Biogas

Biogas typically refers to a mixture of gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced from regionally available raw materials such as recycled waste. It is a renewable energy source and in many cases exerts a very small carbon footprint. Biogas is produced by anaerobic digestion with anaerobic bacteria or fermentation of biodegradable materials such as manure, sewage, municipal waste, green waste, plant material, and crops. It is primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. The gases methane. hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel; it can be used for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat. Biogas can be compressed, the same way natural gas is compressed to CNG, and used to power motor vehicles. In the UK, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel. It qualifies for renewable energy subsidies in some parts of the world. Biogas can be cleaned and upgraded to natural gas standards when it becomes bio methane. It is also used for transportation.

Physics Holiday Homework