Solar Energy: Advantages and Disadvantages of the System - Coursework Example

Assignment Solar Energy Contents P Introduction 2. Advantages and disadvantages of the system 2 3. Solar collection 6 4. Types of Solar collector 11 5. Case study 14 6. Conclusion 17 7. References 18 1. Introduction Solar energy is one of the most significant renewable energies. It is environment friendly and no green house emissions. Solar energy can be transformed to be utilized for diverse purposes that require energy. In order to enhance the efficiency of the solar energy harvesting systems, researchers have been consistently trying to develop and design the technologies to effectively convert the energy into some usable form like converting it to electrical current with the use of solar panels. The most reliable method to evaluate the efficiency of the solar energy converting system is to analyze the solar energy verses the energy converted by the system from the solar energy. In general, solar photovoltaic panels are efficient enough to convert only 15% of the incident solar energy. However, with the help of continuous research in the area helped develop the solar photovoltaic panels that can attain a maximum efficiency of more than 40%. It means that these solar PV panels and solar thermal panels are capable of converting 40% of the incident solar energy into a usable form of electrical current. Arrays of solar Panels are stacked to derive enough current to power a residential unit or an even an industrial unit. 2. Advantages and disadvantages of the system While comparing the solar energy with respective other renewable and non-renewable energy resources, solar energy remains advantageous in most situations. Non-renewable energy resources like coal and oil, solar energy is not only cheaper but environment friendly too. Solar energy is free from hazardous emissions that are mostly associated with the fossil fuel resources. Some of the perspective advantages of the solar energy are given below. 2.1 Advantage: 2.1.1 Predictable Solar energy remains predictable as solar thermal power generation units remain functional throughout the day without any influence of external resource or fossil fuel resource. In daytime, in the presence of sun, solar energy directly converts the thermal content of the solar energy into electrical energy, while some content of this thermal energy is used to enhance the temperature of molten salt that remains hot for longer terns and used to generate electrical energy during night. 2.1.2 No Emissions and it save the eco-systems and biodiversity Solar energy is free from emission that are associated with the fossil fuel resources that solar energy is environment friendly and preserves the biodiversity of the planet by maintain the healthy environment for the humans and for the earthly creatures. 2.1.3 Using Existing Industrial Base Solar thermal power generation units are thermal power generation units which require the thermal energy o change the water to super saturated stream for the generation of energy through turbines. Solar thermal energy requires no extra equipment in the power generation process. The lenses are made for other purposes too. However, solar tubes are made specifically for the power generation units. 2.1.4 Fuel Cost Free Solar Thermal Energy does not need any fuel for transportation like different sources of energy such as fossil fuels. Oil prices are increasing as well as electricity prices are also increasing rapidly in most parts of the world but it can be seen that there are no increases in the cost of solar power, only cost that is involved in the solar energy is the capital cost of the system. Solar energy has no or least operational cost after the initial installation cost is made. Solar energy is free from any requirement of oil, coal or other raw materials for the energy generation process. Thus, solar energy has cost free operation. Solar energy is free from any kind of transportation of fuel or any other type of transportation. Only workers require a transportation facility to be on duty in time. Solar energy can be accessed from any portion of the world, where sun shines. Average life of the solar PV modules and solar thermal modules is about 25-30 years but companies have evolved enhanced the life by 40 years with the use of more reliable materials. 2.2 Solar energy Lackings 2.2.1 Solar Energy is unable to generate power at night The main disadvantage of solar energy is that it is not always constant as a result of the fact that solar power can only be produced when there is sufficient sunlight. Energy must be stored in batteries and the main problem is that the storage capacity may not last the whole night. Solar production decreases during winter periods when the sun radiation is less intense. 2.2.2 Financing Solar power generation units require huge capital investment. Companies that invest in the solar energy recover the amount in more than initial 10 years. 2.2.3 High Costs The cost of solar energy remains at Euro 3.5/watt. Comparatively these costs are much higher as PV solar energy costs as less as Euro 2.5/watt. Thus it is required to reduce the cost further down to enhance the use of solar energy. 2.2.4 Solar panels are bulky Solar panels are too big to easily fit in a closed or bounded space, specially the, silicon crystalline solar cells based modules that have better efficiency that are in most cases covered in glass. The new technology thin-film solar modules are much less bulky but the disadvantage is that the thin-film solar device is currently less efficient than crystalline wafer solar. 2.2.5 Time of Gestation is long enough that is Leads to Cost Overrun The period of gestation which involves aspects such as financing as well as drilling take long periods such as seven years to build a solar thermal power plant that is concentrated. On the other hand, a PV plant requires only about three months in constructing the plant. 3. Solar Collection Solar energy can be directly converted to usable electrical energy by the use of PV (photo-voltaic) or ST (solar thermal) energy conversion methods. 3.1 PV (Photo-Voltaic) PV solar cells are able to convert solar energy into usable electric energy. This electrical energy is direct current DC electrical energy that flows through the semiconductor channel, sourcing from the incident photon and resulting in the generation of electron as the reaction of the surface due to the incident photon. Ideally, the surface should pass an electron through the circuit with energy perspective photon. The DC electricity can be easily converted to be specifically used in our homes and offices and industries with the help of power inverters that convert DC into AC electric power. Photo Voltaic (PV) solar panels can achieve as much efficiency as 15% averagely but newer and more specifically manufactures solar panels can gain about 23% of the efficiency. It is obvious to have knowledge that the output appears on the solar panel is different from the rated output. It is because the solar radiations intensity is unable to maintain its integrity throughout the day due to the revolution of the earth. As the radiation move from one direction to the other, the intensity of the solar radiations becomes weaker or stronger with respect to the angle of the solar module. For example, a 200-Watts solar panel is unable to provide 200 watts of energy throughout the day, in a portion of the day; it will be giving more than 200 watts of energy. The 200 watts are calibrated at 25oC and1000W/m2 pressure. 3.2 ST (Solar Thermal energy) Solar thermal energy harnessing panels are recognized particularly as Solar Hot Water Panel, Solar Thermal Panel, Solar Thermal Collector, Solar Water Heater or Solar Hot Water Collector.  The working principle of the solar thermal collectors is simple; they collect the solar thermal energy and trap it in some type of liquid for its efficient use. In most cases, the liquid used in solar thermal collectors is water that is further used for other purposes. To enhance the efficiency of the solar thermal energy collecting tubes, the tubes are remained clear from outside but covered with energy trapping material from inside. “Tinox”, a company that manufactures solar collecting tubes, manufactures tubes which can attain an efficiency of about 95%.  3.3 Combination of Solar Thermal & Photovoltaic Both the solar thermal energy and the solar PV energy harnessing technologies are different from one another but never compared in respective residential units, as both the technologies have different functions to be utilized in a residential units. Solar thermal technology would preferably replace the hot water geyser while solar PV would replace the electric supply. Electricity generated from the solar system can be used for any application such as water heating. This constitutes the bulk amount of heat required for any household use.  4. Types of solar collector There are two basic types of solar collectors are present: Evacuated tubular collectors (ETC) Flat plate collectors (FPC) with no vacuum. 4.1 Flat plate collectors (FPC) FPCs can have convection barriers between the cover glass and absorber and in some instances they may not have this. A thin plastic frustrate is used to make a convection fence that remains in between the glass cover and inner tube absorber. The gap between the absorber and cover glass is very important as it helps in improving heat gain due to lack of heat loss due to convection. Figure A-- Flat plate collector The convection barrier is important in maintaining the trapped air circulation in between the glass cover and the inner absorber. In this manner, the thermal energy that may have been lost due to radiation remains trapped inside the thermal structure of the medium. However, the absorption medium is bounded in limits to absorb energy. The absorb energy remain under certain limits. The convection is important to enhance the efficiency and the economy of the solar collector plate. 4.2 Evacuated tubular solar energy collectors Various methods are utilized to make Evacuated tubular collectors (ETCs). However, the principle used in all kinds of ETCs is same. All make utilisation of the vacuum tubes to absorb solar energy. Figure 4.2 depicts an ETC. Figure 4.2- Evacuated tube solar collector The thermal energy, in ETCs, can be absorbed through the use of solar collector fluid flowing through the absorber or else it can be collected via heat pipe principle where little fluid remains inside the evacuated tubes. The transfer of energy occurs in 4 preceding steps: 1. Evaporation of the liquid takes place through solar radiation process. 2. The vapours formed in this manner are lighter than air and elevate in upward direction. In the upward direction that pipes have still lower temperature and some liquid at lower temperature still remain through pipes. 3. Condensation of the vapour takes place. 4. The condensed fluid moves to the bottom triggering the start of the process again. ETCs are also function as “U-pipe” to replace thermal panel to enable heat to flow through one single pipe. Behind the collectors, concave mirrors are placed to increase the efficiency of the solar collection tubes by enhancing the solar radiations and focussing them behind the axis of the tubes. The reflectors are generally made from higher reflecting materials but polished aluminium can also be used instead of costly materials. The rear side of the absorption tubular structure should have a discriminating surface just as the front in order for it to be efficient. 5. Case study Case study 1: “Hong Kong International Terminals Limited (HIT)” Hong Kong International Terminals Limited (HIT) made a decision to utilize the solar energy for the good of the environment and to reduce the influence of fossil fuel resources on the HIT. The company Added 129 solar PV Panels that in combination generate about 19, 200 kWh of energy annually. The project estimates to give 19, 200 kWh of energy annually. A gird tie solar power generation system is used to at the CLP. The solar panels not only generate enough power for the CLP but also supply the surplus to the grid that is further used in further electrical operations. Like lights, and other equipment. At night, the grid is automatically shifted to the electrical supply power. Case study 2: “HK Electric” HK Electric, the power generation company in Hong Kong, established that massive solar photovoltaic power generation system of 1MW and in recent years, the company expanded the power generations system and added 550 KW of power in the system with the help of solar PV panels. The company invested in the latest technology of “amorphous/microcrystalline silicon tandem junction thin-film photovoltaic (PV) modules” considering the massive scale of the project. In this manner higher efficiency is achieved. The project now has a total of 8,662 PV modules with a recent addition of 3000 PV modules. These modules are not placed on ground but placed over the roof tops of the smaller or larger building compounds in the boundaries of Lamma Power Station which has an area of about thirteen thousand square meters. The plant generated about 2.26 million units of emission free electrical energy. When the power generation unit was completed in 2011, about 1.1 million annual units of emission free electrical energy had been generated that reduced 915 tonnes of carbon dioxide emissions equaling to planting of 39,000 trees. 6. Conclusion In Hong Kong solar energy is progressing at a rapid pace due to the high abundance of the resource and due to the economical benefits as well as environmental benefits. In general, Hong Kong is comprised of elevated and sky high building that restrict the proper solar energy in particularly dense urban regions. On the other hand, the businesses today are not thinking about the future of the earth. The businesses are not willing to invest in the renewable energy resources. Government should emphasize on the solar and other renewable energy resource and encourage the investors to invest in the renewable technologies. Currently renewable energy resources have limited applications that restrict the proper use of renewable energy resources. This condition is crushing the people not only economically but also environmentally. There have been interesting results derived from using solar systems in the area. For instance, wind and solar energy have been proposed to be used in the "Hong Kong Disneyland."It has also been proposed that solar power can be used to provide lighting in tunnels and other areas in Hong Kong. 7. References Boxwell, M, 2010, Solar Electricity Handbook, Edition: A Simple. Foley, E, 2012, Solar Panels On the Move. Garg, HP 1990,Solar Energy:Fundamentals And Applications(1ST REV ) Parida, B, Iniyan, S &and Goicm R 2011, “A review of solar photovoltaic technologies,” Renewable and Sustainable Energy Reviews, 15 (3): 1625-1636. Practical Guide to Solar Energy n.d., Designing and Installing Photovoltaic Solar Electric Systems Rashid, M 2007 , Solar Power Conversion, Power Electronics Handbook Sailor, DJ, Wamser, C & Rosenstiel, T 2011) “Solar PV and green roof integration --performance and design considerations,” An invited presentation at the 8th Annual Green Roof & Wall Conference – Cities Alive, Vancouver, Canada. Chen, CJ 2011, Physics of Solar energy http://www.hit.com.hk/cn/Corporate-Social-Responsibility/Sustainability/Major-Achievements-Environmental-Protection.html http://www.hkelectric.com/web/Index_en.htm Read More