Alternative energies include solar, wind, geothermal, biofuels, hydrogen, nuclear, and hydroelectric. Solar energy converts sunlight into electricity using photovoltaics or concentrated solar power, while wind turbines convert wind's kinetic energy into electricity. Geothermal energy utilizes heat from within the earth, and biofuels like ethanol are plant-derived fuel substitutes. Nuclear energy generates electricity through nuclear fission, and hydroelectricity uses water's gravitational force. Each energy source has pros like being renewable but also cons such as intermittency, high costs, or environmental impacts.

1. Alternative energyBy: OngKian Han of 2P320

2. What kind of alternative energies are there?Solar energy (generating of electricity from sun)Wind energy (generating of electricity from wind)Geothermal energy (using hot water or steam from the Earth’s interior for heating buildings or electricity generation)Biofuel and Ethanol (plant-derived substitutes of gasoline for powering vehicles)Hydrogen (used as clean fuel for airplanes, spaceships, and vehicles)Nuclear energy ( generating of electricity by using nuclear fission)Hydroelectricity(generating electricity by using gravitational force of flowing water)

3. Solar energySolar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP) or to split water and create hydrogen fuel using techniques of artificial photosynthesis.

4. Concentrated Solar Power(CSP)Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam.Commercial concentrated solar power plants were first developed in the 1980s.

5. PhotovoltaicsPhotovoltaics converts light into electric current using the photoelectric effect.Photoelectric effect: electrons are emitted from matter (metals and non-metallic solids, liquids or gases) as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light

6. Pros and Cons:Pros:Cons:Renewable energyDoes not pollute the Earth a lotGreatly reduced contribution to global warmingInfinite energy resourceReduced maintenance costsFalling production costsLow running costsLocal applicationHealth and safety benefitsReliabilityFirstly, some countries receive less sunlight and thus solar energy is not very effective there.Solar energy cannot be directly available during the night or when they are clouds as they block the sun’s rays.Direct current(DC) power is produced by solar cells which must be converted to Alternating Current (AC) power before it can be used.

7. Wind energyConversion of wind energy into electrical energy by spinning turbines Mechanical power for wind millsWind pumps for pumping water or drainage.

8. Wind turbines:A wind turbine is a device that converts kinetic energy from the wind into mechanical energy.A wind turbine which uses this mechanical energy to produce electrical energy.If the mechanical energy is used to drive machinery, such as for grinding grain or pumping water, the device is called a windmill or wind pump

9. Pros and Cons:Pros:CONS:Free and in abundanceDoes not generate pollutionIs renewableCan generate enough energy for large numbers of people by using larger turbinesIt is infiniteWind power can be used when electricity is down during a blackout.Reliability of wind is not always goodAre known to endanger wildlifeLightning causes a lot of damage to wind turbines, thus the need for frequent maintanenceCan only be stored with a batteryThere is some noise pollution, although not much.Not a lot of places are suitable for turbines.

10. Geothermal energyGeothermal energy is thermal energy generated and stored in the Earth.Earth's geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, from volcanic activity, and from solar energy absorbed at the surface.

11. Pros and ConsPROS:CONS:Geothermal power is cost effective, reliable, sustainable and environmental friendly.Fluids drawn from the deep earth carry a mixture of gases, notably carbon dioxide (CO2), hydrogen sulfide (H2S), methane (CH4) and ammonia (NH3).hot water from geothermal sources may hold in solution trace amounts of toxic chemicals such as mercury, arsenic, boron, and antimony.adversely affect land stability.Geothermal plants use a lot of fossil fuel or coal or nuclear,and freshwater.

12. Ethanol fuelEthanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages.It is most often used as a motor fuel, mainly as a biofuel additive for gasoline.

13. Pros and Cons:Pros:Cons:It is renewableIn small percentages, along with gasoline, ethanol has helped reduce the emissions of various toxic volatile gases and particulate matter.Use of ethanol also leads to long term corrosion of engines, thus permanently damaging the vehicle.There have also been instances of ethanol fuel problems for boaters, who say that switching to ethanol causes fiberglass fuel tank corrosion, blocking of the filters and increased contamination.Higher ratios of ethanol to gasoline have more pollution than gasoline fuels.May be more expensive then gasoline fuel.A great number of scientists also question the use of food crops to create fuel, when a great majority of the world population, especially in undeveloped countries still face a shortage of food.

14. Nuclear energyNuclear power is the use of sustained Nuclear fission to generate heat and do useful work.Nuclear power provides about 6% of the world's energy and 13–14% of the world's electricity.

15. Nuclear fissionnuclear reaction in which the nucleus of an atom splits into smaller parts (lighter nuclei), often producing free neutrons and photons (in the form of gamma rays).

16. Pros and ConsPROS:CONS:Little pollutionQuite reliableMeltdowns such as ChernobylRadiationWaste disposal

17. HydroelectricityHydroelectricity 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.his was approximately 20% of the world's electricity, and accounted for about 88% of electricity from renewable sources.Dams such as the Hoover Dam

18. Pros and Cons:Pros:CONS:RenewableIs reliable and consistentCompletely independent of fossil fuel except during construction of the damDoes not release poisonous gases into the airPower generation is almost instaneousOperational costs are quite low and is a clean way of producing energy as used water can be used for agriculture, irrigation.It requires a lot of time and money, and a lot of land.There is a risk of the dam bursting after torrential rainfallMay effect the environment around the areaDroughts can severely affect the damsSilt(granular material of a size somewhere between sand and clay derived from soil or rock) is a problem.

19. Bibliographyhttp://www.alternate-energy-sources.com/advantages-of-solar-energy.htmlhttp://www.solar-and-wind-power-source.com/wind-energy-pros-and-cons.htmlhttp://www.energy-consumers-edge.com/pros_and_cons_of_geothermal_energy.htmlhttp://rodgerliu0.tripod.com/id2.htmlhttp://www.buzzle.com/articles/ethanol-fuel-pros-and-cons.htmlhttp://members.tripod.com/funk_phenomenon/nuclear/procon.htmhttp://www.buzzle.com/articles/hydroelectricity-pros-and-cons.htmlhttp://en.wikipedia.org

20. THANK YOU