These are some comments on this research paper we have to consider and you will see Bold writing when you reread the essay, from my professor.

ENERGY

These are some comments on this research paper we have to consider and you will see Bold writing when you reread the essay, from my professor.

• Reorganize the introduction from broader to narrower topics.
• Revise the thesis from an announcement to a specific argument about solar power.
• End body paragraphs with your own analysis rather than on borrowed information.

 

RENEWABLE ENERGY

INTRODUCTION

Hydroelectric power, solar power, geothermal power, and wind are the commonly used sources of energy in the 21st century. The four sources of energy have a significant contribution in creating sustainable systems of energy. They play a great role in helping to mitigate against effects of climate change increasing the security of global energy supply systems and giving developing countries cheap energy supporting millennium development goals. However, solar energy is the most common source of energy developed today and has evolved through time to change the energy sector in the world today. If enough resources are pumped into renewable energies, they could support half of the energy demand in the world by 2050 [1].

Solar Energy plays a vital role in renewable energy by creating electricity that drives forward all the human activities that need a source of power. Most countries today use solar energy alongside other sources of energy because the sun shines every day and provide heat and light energy that does not have an end. Its role in driving economies, therefore, cannot be downplayed and it exercises greater influence than other sources of energy due to its qualitative effects.

Renewable energy is an integral element in theproduction and any shortcoming on its part is widely felt economically since it is a central concept in most branches encompassing natural science, engineering, and social science. Carbon heavy fuels like fossil fuels, coal, and natural gas are an essential ingredient to industrialization but their rates of replenishment is limited or nonexistent and thus are not able to cope with energy demands in the society. It is therefore of great importance to supplement energy derived from them with renewable sources of energy with the ultimate intention of ceasing production from carbon heavy processes and fully embracing renewable energy [2].

The shift of emphasis to renewable resources would also be a significant step in realizing green energy and reducing waste of natural resources. Our planet has been in existence for billions of years and ever since time immemorial human beings have harnessed the power of the sun for primary energy needs. The big question that has astonished researchers is why we cannot harness the power of the sun to power our cars and homes. In this endeavor, scientists have played a leading role in developing alternative energy called “green energy.”

This is composed of energy derived from:

• Wind
• Geothermal
• Solar (the sun)
• Moving water

Some background information on how power is derived from those sources is as listed below;

• Wind energy- this converts power available in themovement of air to electricity. The advantage of the type of power production is that it does not generate emissions thereby polluting the environment, does not make solid waste neither is it dependent on usage of water.
• Geothermal –Geothermal power production uses heat derived from the core of the earth to make energy that is clean and efficient.
• Sun- Solar power captures light from the sun to generate electricity. Solar energy produces no emissions, generates no waste and neither does it use water.
• Moving water- Hydroelectric power is captured from energy that is derived from falling water. No emissions or solid wastes are produced although it can have some relatively high or low impact on the environment based on the location of the plant, water flow maintenance and water quality. It can have an impact on fishing and land use in reclaimed areas for reservoir.

Cost of power has been a limiting factor for themost part; whether it is the cost of technology, the cost of replacing fossil fuels or the cost of putting up expensive sources like nuclear powers, it is equally prohibitive. There are however some downfalls of nuclear energy or fossil fuel energies which solar energy can replace. These can be summarized as:

• Emission of sulfur dioxide, which is the primary cause of acid rain, contains some very small particles of soot. The particles are mainly responsible for mushrooming of air pollution related to deaths in the globe.
• Smog, which is formed by combination of nitrogen dioxide combining with organic compounds in the environment that highly contribute to stresses in the ecosystem of forests. High levels of smog triggers respiratory issue in humans and in some cases lead to death [3].
• Around a third of carbon dioxide, which is the leading gas that traps heat causing global warming may lead to floods, droughts, disease, and disruption of the ecosystem or in general severe weather.
• Toxic metals emission and nuclear waste.

This project will expound on possibilities and uses of solar power in the society and ways on which it will function. It is imperative to look at energy from the sun right from the beginning;

RESEARCH ON SOLAR ENERGY

Main study when talking about solar is centered on photovoltaic or PV derived from the two words (photo=light and voltaic= electricity). Photovoltaic is a semiconductor technology that converts energy from light into Dc (Direct Current) without using any movable parts, creating any pollution or consumingconventional fuels [4].

Solar cells are devices made of photovoltaic cells with the aim of converting solar energy into electricity either directly or at first converting them into heat energy or chemical energy and then to electrical energy. The most common of the technologies is the use of photovoltaic effect, which entails light falling on two layers of semiconductors that in turn produce voltage whose potential difference is used to drive current through external circuit thereby giving out useful output.

Photovoltaic effect is important in solar energy because it provides current and voltage when lights continue to fall on the solar panel. The current is used as a source of power in electrical circuit and in measuring the brightness of the incident light.
A classic example of solar development is in Australia where it has been stimulated by:

1. Need for low maintenance and long lasting energy source that is deployable and suitable to low habitation places and off the national grid. These areas have satellites, water-pumping sites in remote areas, lighthouses, and outback telecommunication stations.
2. Need for cost effective supply of power to people in areas that are far off the grid like the aboriginal settlements, sheep, and cattle stations.

• Need for power that is nonpolluting and silent in reserved areas like tourist attraction sites, campers, and caravans.

1. Need for flexible and convenient source of asmall amount of energy to power small devices like calculators, light meters, cameras, and watches.

These needs have combined to produce a growing market in photovoltaic cells stimulating innovation. With the growth of the market and anincrease in the number of devices in production, the cost of cells has been on a downward spiral. New applications for producing the cells have been discovered further increasing options to come up with the most cost effective product.

To understand fully how power energy is created from solar, it is important to look at how the silicon cells are made through crystal wafers, either thin films or polycrystalline wafers. Single crystal wafers are sliced which are approximately a third or a half millimeter thick from large crystal ingot grown at around 1400 °C; a very expensive process. Silicon used should be of a very high quality having near perfect crystal structure [5].This is,however, the traditional way of producing electricity but technology has changed and scientists no longer need to use batteries on solar cell devices. Today solar cell devices only need light to work and so there is need to meet the criteria required. When these criteria are not met, then there will be inefficiency since silicon arranged in pure crystalline structure is not an electrical conductor. Electron will also fail to move around and fill the gaps that create an electric field in a solar panel.
Polycrystalline wafers are made through casting process where molten silicon is allowed to set in a mold then sliced into wafers. This makes them cheaper to produce, but their efficiency is eroded. Inefficiency is brought about by imperfections from the casting process. Around half of the silicon is lost as dust in both processes.
Amorphous silicon, which is one of the thin film technologies, is made from depositing silicon into aglass substrate from reactive gas like silane(siH4). It is applied as a film to glass or plastic, which are low-cost substrates. Thin film cells have many advantages due to their easier deposition, high suitability, ease of mass production and ability to be deposited to building materials.

Since solar cells are mainly made from materials that used in electronics (semiconductors in silicon) whose cost has been going down with time, their overall usage and affordability is then bound to be on an upward trend. It is an important option in renewable energies drive [6].

A typical layout diagram of how solar power is harnessed is as shown below;

Fig 1: Harnessing solar power

WIND ENERGY

For centuries, windmills have been used in grinding grain and pumping water in rural areas.  The driving force in them which is wind is occasioned by earth rotation and heating of the atmosphere. They have global patterns, are semi-continuous and affected by topography, hourly, daily, and seasonal variations. Annual kinetic energy of moving air in theatmosphere is about 3x 1015kWh or approximately 0.2 % of solar energy hitting earth [7].

Maximum potential is about 30 trillion kWh, which is around 35% of total consumption in the world. Power carried by wind at 25.6km/h is 200 W/m2 of thearea covered by windmill vanes and 35% of it can be converted to electricity. It is however important to note that windmill power output varies with thecube of wind speed. This makes it economically viable to harness this source of power only from coastal areas or from windy locations on mountainous areas. Wind, however, requires extensive coverage in thearea needed to produce asignificant amount of energy as shown in the photo below.

Fig 2: An expansive area for collecting wind energy

1. HYDROELECTRIC ENERGY

This energy source uses thegravitational potential derived from elevated water to turn turbines at high flow speed. It owes its position as a renewable energy source by the fact that rain cycles are repetitive and any water that is used will ultimately be replenished. The water coming from rain flows from rivers and streams and ends up in the oceans where it is evaporated into the atmosphere beginning the whole cycle again. The cycle is precipitation dependent and sometimes mostly unreliable if forecast precipitation fails to get to volumes needed [10].

Harnessing of energy from falling water with the aim of mechanical power provision has been one of humankind greatest achievement. Man has used water driven wheels to provide grinding power for pounding grains since agrarian revolution. Industrial revolution however brought about need for more power and design of water wheels had to change to accomplish this need.

2. HYDROGEN AND FUEL CELLS

Hydrogen and fuel cells are strictly not renewable sources of energy, but they are abundant in nature and when utilized have very little pollution. Hydrogen is used in fuel cells, which are like batteries to produce power for an electric motor. Significant hydrogen production requires ample power. Fuel cells are then used to convert the chemical energy into electricity through an oxidizing reacted with oxygen. Unlike batteries, fuel cells must be supplied with oxygen to sustain reactions. With a constant supply of inputs, a continuous burn is guaranteed maintaining a constant energy source. Water is the only product and thus this source of energy is not a pollutant to the environment.

3. GEOTHERMAL POWER

The earth’s internal energy comes from the decay of radioactive matter in the earth’s crust and the continual loss of energy after the earth’s formation. The water in the earth’s crust is heated and come out as fissures or hot springs. Dry steam power plants, binary cycle power plants and flash steam power plants are among the technologies used in generating electricity from geothermal energy. The thermal heat must flow to the earth’s surface because electricity generation requires high temperatures and the heat is Carried out to the earth’s surface by hydrothermal circulation, oil wells, magma conduits, drilled wells or the combination of all these. The flow can occur naturally in the case of a thin crust. Geothermal power is sustainable as the heat extraction is small when compared to the heat content from the earth. However, extractions are still monitored to prevent local depletion.

OTHER FORMS OF ENERGY

Energy derived from tidal waves, oceans or hot hydrogen fusion can also be effectively used to generate power. The tides rotate huge turbines that have dynamos attached. This is a clean form of energy as there is theabsence of by-products that could pollute the environment. The hot hydrogen fusions involve the fusion of atoms [8]. This, when the reactions are exothermic, can generateenormous amounts of heat. This heat can be used in one way or the other with no pollution of the environment. The forms of energy-harnessing have one drawback to the other and can barely be relied upon to generate power for aconsiderable period

CONCLUSION

The biggest advantage of using renewable sources of energy is that they are infinite and therefore sustainable as the probability of them running out is little. Renewable sources of energy in most circumstances require little or no maintenance as compared to conventional sources of energy. Since their fuel is derived from natural resources abundantly available, cost of power production is minimal after the initial cost of putting up power plants is factored in [11].

What is even more noteworthy is that renewable sources of energy are associated with no waste products and therefore have minimal adverse effect on the environment. Since the location of some of them like solar energy is far away from urban centers an added benefit of opening up economic benefits to communities is also associated with renewable sources of power. It is thus imperative for humanity to focus on these methods of harnessing power from the environment if we are to act more responsibly to the future generations [9]. The initial costs of harnessing power from these sources may be daunting but if we were to rededicate our efforts to making our world better, we would all stand to reap accruing cheap power in years to come.

 

REFERENCES

1. L. Henrick, Renewable Energy Systems: The Choice and Modeling of 100% Renewable Solutions. New York, NY: Academic Press, 2009, pp. 83-87.
2. Q. Volker, Understanding Renewable Energy Systems. London: Earthscan, 2005, pp 58-61
3. J. Dilwyn. Renewable Energy Systems: The Earthscan Expert Guide to Renewable Energy Technologies for Home and Business. London: Routledge, 2013, pp 45-87
4. G. Gary, Electrical Theory for Renewable Energy.Boston, MA: Cengage Learning, 2012, pp 119
5. Soteris, K. Artificial Intelligence in Energy and Renewable Energy Systems.Hauppauge, New York: Nova Publishers, 2007, pp 126
6. D. Mukherjee,Fundamentals of Renewable Energy Systems. Daryaganj, New Delhi: New Age International, 2007 pp 54
7. J. Twidell, and A.D. Weir, Renewable Energy Resources.Milton Park, Abingdon: Taylor & Francis, 2006, pp 102
8. G. Swanson, Being Green and the Common Citizen: Developing Alternative Methods of Renewable Energy Investment through Solar Power and Efficient Building Design. Ann Arbor, Michigan: ProQuest, 2008, pp 185
9. A. Pandit, (‎2008). Harnessing Solar Energy for the Production of Clean Fuels. [Online] Available: http://www.esf.org/fileadmin/Public_documents/Publications/CleanSolarFuel_01.pdf
10. Legislative Research Commission (August 27, 2009). Energy-efficient Building Design and Construction Practices. [Online] Available: http://www.lrc.ky.gov/lrcpubs/rm503.pdf
11. S. Palit.(2013). “The sustainability and future of energy and environment – a vision to target.”International Letters of Chemistry, Physics and Astronomy [Online] 5 (1), pp. 47-56

 

…………..Answer Preview……………..

There are several types of energy. In the 21^st century however, the most common types of energy are solar power, hydroelectric power, wind energy and geothermal power. These sources contribute significantly to the balance of a sustainable energy system. Solar energy technology is based on photovoltaic technology (derived from light=photo and electricity=voltaic). The solar devices are composed of photovoltaic cells whose purpose is to convert light energy to electric energy. The silicon cells are made through crystal wafers. The silicon is of high quality making the crystal structure perfect. Amorphous…………………

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