Generation and Distribution of Electrical Energy Investigation - Term Paper Example

Generation & Distribution of Electrical Energy Investigation 1. Introduction Various renewable and inexpensive sources of energy were introduced in the 21st century and these widely available energy sources are converted to usable forms such as electricity to provide developed countries with higher standard of living and support others in their economic development (National Research Council, 2001, 9). Since then demand for electricity increased worldwide and in the 1990s alone, the world consumed an estimated 11 trillion kW-hr of electricity per year. Moreover, studies show that by 2020, the world’s electricity consumption will reach approximately 22 trillion kW-hr (ibid, p.10). Electrical energy today is generated, transported, and distributed in a number of ways (Kamaraju, 2009, p.1) but not all of them are necessarily efficient as some of them have limited capacity, environmental impact, and impractical in terms of cost and economy. The following sections discusses the different methods of generating and distributing electrical energy, their advantages and disadvantages, 2. Methods of Generation and Distribution of Electrical Energy 2.1 Conventional sources of electrical energy According to Banad (2010), electrical can be generated from hydroelectric power plant, thermal power plant, diesel generating power stations, and nuclear power plant (p.2). A hydroelectric plant is an effective source of energy since water is a renewable source of energy but it can also damage the ecological system, community, and social structures. For instance, most hydroelectric systems are being built in mountainous regions and construction of dams often result to significant number of displaced people as in the case of Kariba dam in Zimbabwe and the Chinese Three Gorge project (Wengemayr & Buhrke, 2011 , Summary). Similarly, thermal power plants require significant amounts of water from mineral extraction to transmission and distribution of electrical power. However, the greater demand for water comes from the need to cool turbines in the power plant, which according to UN’s World Water Assessment report is contributing to 10 to 1,500 mm of water level withdrawal per year in the U.S. and Europe alone. Moreover, water used for cooling turbines is commonly disposed to natural watercourses, which is detrimental to downstream aquatic life (UN, 2003, p.263). Diesel electric plants are usually used to supplement hydroelectric or thermal power stations as their electric generating power is limited to small area. Sometimes called “nursery stations” (Nag, 2008, p.735), diesel electric plants are mobile as they can be mounted in trailers to supply electricity to remote construction sites or small town. They can act as stand-by units for hydroelectric plants or electric generators during power interruption in critical structures such as hospital, industrial plant, and so on. This type of electric generation is convenient to design and install, cheap and easily available, flexible with load changes, need small space, requires minimal water for cooling, and mobile. However, diesel electric plants operating and maintenance cost is high compared to other sources of electricity, its capacity is limited, it is typically noisy, emit smoke and other contaminants in the environment (ibid, p.735). Electric power generation in a nuclear plant involves controlled nuclear reaction to boil a certain amount of water to produce steam that would spin a turbine that actually generates electricity. LWRs of Light-water reactors produce 85% of world’s nuclear-generated electricity. It has low environmental impact and accident risk but it produces radioactive waste from spent fuel rods and expensive to maintain (Miller & Spoolman, 2007, p.295). 2.2 Non-conventional and renewable sources of electrical energy Non-conventional generators of electrical energy include solar energy, wind energy, tidal or ocean energy, biomass, hydrogen, geothermal, and fuel cells (Banad, 2010, p.2). Solar electricity or taking energy from the sun to produce electricity is a brilliant concept as this source of energy, which aside from being free and environmental friendly is available, anywhere. Through solar or photovoltaic panels, energy from the sun is converted to electrical energy that can power electric devices in houses, schools, and others. However, although it is non-polluting and readily available, solar panels are expensive and its capability to generate electricity is limited to daytime. Moreover, a standard solar panel can only power two or three bulbs of lights thus to run small electrical equipments such as refrigerators, TV, water pumps, and so on, more panels are required (Erasmus, 2002, p.133). Similar to solar energy, wind and ocean energy is somewhat inexhaustible, affordable, and widely available. Wind turbines primary function is to generate electricity (Manwell et al, 2009, p.205) which is technically converting the kinetic energy of the wind to mechanical energy through rotational motion of their blades and electric generator. Wind energy is renewable, does not require fuel and transportation facility, environment friendly, and cost less in terms of maintenance. However, wind is a fluctuating source of energy thus requiring auxiliary storage devices. It is typically noisy, require large a space, and a very difficult to build (Sivanagaraju, 2010, p.79). Compared to wind, ocean or tidal power is more stable with less than 5% annual variation. The ocean provide kinetic energy through tides and waves (Barbir, 2010, p.226) The tidal power plant in Upper Cook Inlet in Alaska can generate 750,000 kW to 2,600,000 kW of cheap, inexhaustible, and pollution free electricity (Charlier & Justus, 1993, p.325). However, its construction cost is high and estimated to be within the vicinity of $ 4 million per megawatt. Barrages for power generation have environmental impacts such as flooding and significant destruction of coastline (Barbir, 2010, p.227). Biomass burns plant materials, agricultural and animal waste to generate electricity (Miller & Spoolman, 2011, p.419). It is a renewable source of electricity in the sense that forest products, agricultural waste, and so on are renewable provided it can be replenished in a timely manner. The problem with biomass however is that repeated cycles of growing and harvesting deplete soil nutrients, degrades biodiversity in forest, and reduced vegetation’s ability to absorb carbon dioxide. More importantly, study shows that biomass electricity production is only 30 to 40% efficient (ibid, p.420). Hydrogen fuel is a promising source of electricity as it could eliminate most outdoor air pollution as it does not produce carbon dioxide, produced using widely abundant water, and 45 to 65% efficient in fuel cells. However, like solar panels, hydrogen fuel cells are generally expensive and needs additional storage and distribution system (Miller & Spoolman, 2011, p.221). Figure 1- Hydrogen fuel extraction - (Alternative energy.com, 2012) In contrast, geothermal energy can provide 24/7 base load electricity, with average capacity factor from 67 to 90% which is comparable to fossil or nuclear sources of energy. It typically only require around 0.3 km2 of land, relatively simple to build, and does not need large transportation infrastructure. The main drawback however is that geothermal heat produces contaminant such as carbon dioxide, hydrogen sulphide, ammonia, methane, and so on, which is almost half of those produced in coal-fired plants. Moreover, geothermal fields can lead to other problems such a land subsidence, induction, and micro-earthquakes (Balzani, 2010, p.249). Figure 2 - Geothermal power extraction (Nomad4ever.com, 2012) Fuel cells use hydrogen and oxygen to generate electricity and their by products are water and heat thus no greenhouse gas emissions. It is highly efficient at 85%, quiet and clean to operate, and aside from electricity generation, it can be use to power electronic devices, vehicle, building back-up system, and others. However, hydrogen production, storage, and transportation are expensive. It is a new technology and there still no proof of its reliability, durability, and environmental impact (Asplun, 2008, p.149). Figure 3- Basic hydrogen-oxygen fuel cells (Herman, 2010) 2.3 Most Efficient Method of Generating Electrical Energy By analysis, if environmental impact is not an issue or technology is available to prevent such harmful emissions, geothermal power is the most viable method for generating electrical energy. Similarly, if technology is available to reduce the cost of hydrogen production, fuel cells are better alternative to fossil, hydro, tidal, and nuclear power. The main problem with existing sources of energy for generating electricity is their respective environmental impact and absence of supporting technology to reduce their cost. For instance, nuclear power as discussed earlier is a reliable source of electricity but it by products or radioactive waste is a big disadvantage. Similarly, slow development in solar electricity’s supporting technology makes application of solar power limited and expensive. Since fuel cells is a new technology that still require further evaluation to determine its real capacity to generate adequate electricity, solar electricity at this point is the most efficient method for electrical energy generation compared to conventional and non-renewable sources of energy. It has no environmental impact, no harmful emissions, and it can provide AC or DC to consumer without additional transmission and distribution cost. If supporting technologies is developed, solar energy may be harness and store at daytime and can be a reliable and cheap source of electricity for many applications particularly when it is producing both AC and DC. 2.4 Most Efficient Method of Distributing Electrical Energy Electrical power systems are highly dependent on power distribution networks such as those used to transfer from power plant to industries, homes, commercial buildings, and others (Fardo & Patrick, 2009, p.207). Majority of high voltage electricity today is distributed in AC form through transformers, transmission lines, feeders, distributors, and service mains (Bakshi & Bakshi, 2007, p.367) as shown below. Figure 4- Typical AC distribution scheme (Bakshi & Bakshi, 2007) The AC form of distribution, both overhead and underground, is often seen as much simple and economical to DC method. This type of distribution system comes with three different connection scheme – radial, ring main and inter-connected systems (Tewari, 2003, p.758). The DC distribution system on the other hand use direct current generators and convert AC to DC using mercury arc rectifiers, rotary converters, and so on at the substations (Bakshi & Bakshi, 2007,p.368). Figure 5- DC Transmission and Distribution scheme (Bakshi & Bakshi, 2007) Evaluation of transmission and distribution cost between AC and DC suggest that when capital investment for the actual infrastructure – towers, conductors, insulators, terminal equipment- and cost of operation is computed and similar insulation requirements is use for peak voltage levels, a DC line can accommodate more power with two conductors compared to AC with three conductors with similar size. About two-thirds of power transmission loses is also reduced using DC system. AC system is only economical in distances less than the breakeven distance or 500 to 800km due to terminal equipment and line cost as shown below (Rashid, 2010, p.826). Figure 6- Comparison between AC and DC system transmission cost (Rashid, 2010) DC system has full control of over transmitted power and do not have stability limits caused by long transmission distance in AC systems. According to Padiyar (1990), in terms of economic and technical performance, DC is more advantageous in long distance bulk power transmission when breakeven distance concept is concern (p.7). Most modern electronic equipment run on DC and according to 2007 EPA report, up to $4 billion annual electricity cost can be saved if DC system is used in the United States (Curtis, 2011, p.65). This is because DC needs no further conversions, eliminate points of failure due to multiple distribution and conversion components, a 380 V DC system can increase reliability by 200%, facilitate on-site power generation from renewable energy sources such as sola PV arrays, wind power, and fuel cells without power conversion (ibid, p.65). 3. Future Needs for Electrical Energy In the same manner that the 21st century saw the decline of coal-fired power plants, demand for electricity in the near future will likely experience considerable decline in grid distributed electrical power. This is because off-grid sources of electricity such as fuel cells will be more prevalent due to the need to conserve, recapture, and cogenerate energy (Haven, 2011, p.156). Dependence on oil will be reduced considerably and maybe replaced by natural gas and other renewable energy technologies such as solar electricity that can be generated and distributed close to consumers (Jamasb et al, 2006, p.12). However, study shows that the world’s energy consumption is growing by 1.7% per year while demand for electricity is increasing by 2.6% annually which by analysis is too great for renewable energy source unless solar power is exploited in a more efficient and economical manner (Schernikau, 2010, p.14). 4. Recommendation/Proposal for Other Source of Energy (Safety and Reliability) As mentioned earlier, safety of the population and the environment is the primary concern in electricity generation thus the most efficient source of energy is one that satisfies both safety and reliability requirements at the same time. For this reason, since transmission and distribution of electrical energy is also a major issue, this report’s recommend complementary combination of solar and fuel cells as primary source of electricity. This is because they do not have any environmental impact and their source of energy is virtually unlimited. Moreover, they need no transmission towers and lines, consume less space, they can carry both AC and DC current, cost less in terms of supporting infrastructure; and with further development, they can generate as much power as conventional power source in a safe and reliable manner. 5. Conclusion There are a number of methods of electrical energy generation and distribution but not all of them are efficient, safe and reliable. The most favoured however are those methods that extract energy from renewable sources except from biomass which environmental impact undoubtedly significant. With further development, solar power and fuel cells are the most promising source of electrical energy. Similarly, compared to the cost, reliability, and intended use of AC, DC is the most feasible method of distribution as most modern devices are running on DC. Solar and fuel cells is highly recommended as they are safe and can be a very reliable source of electricity if fully developed. 6. Reference List Alternative Energy.com (2012), Hydrogen Fuel, available online at http://www.alternative-energy-news.info/technology/hydrogen-fuel/ Asplund R, (2008), Profiting from clean energy: A complete guide to trading green in solar, wind, ethanol, fuel cell, power efficiency, carbon credit industries, and more, John Wiley & Sons, U.S. Bakshi M. & Bakshi U, (2007), Electrical Power Transmission and Distribution, Technical Publications, India Balzani V. & Armaroli N, (2010), Energy for a sustainable world: From the Oil Age to a Sun-Powered Future, John Wiley & Sons, U.S. Banad, M, (2010), Elements of Electrical Engineering, Laxmi Publications, New Delhi Barbir F, (2010), Energy Options Impact on Regional Security, Springer, Germany Boxwell M, (2011), Solar Electricity Handbook- 2011 Edition, Greenstream Publishing, U.S. Charlier R. & Justus J, (1993), Ocean energies: environmental, economic, and technological aspects of alternative power sources, Elsevier, U.K. Curtis P, (2011), Maintaining Mission Critical Systems in a 24/7 Environment, John Wiley & Sons, U.S. Erasmus R, (2002), Science Matters: Module 3- Energy and Change, Pearson South Africa, South Africa Fardo S. & Patrick D, (2009), Electrical Power Systems Technology, The Fairmont Press, U.S. Haven K, (2011), Green Electricity: 25 Green Technologies That Will Electrify Your Future, ABC-CLIO, U.S. Herman S, (2010), Delmar’s Standard Textbook of Electricity, Cengage Learning, U.S. Jamasb T, Nuttal W, & Pollitt M, (2006), Future Electricity Technologies and Systems, Cambridge University Press, U.S. Kamaraju P, (2009), Electrical Power Distribution System, Tata McGraw-Hill Education, India Manwell J, McGowan J, & Rogers A, (2009), Wind Energy Explained: Theory, Design and Application, John Wiley & Sons, U.S. Miller G. & Spoolman S, (2007), Environmental science: problems, concepts, and solutions, Cengage Learning, U.S. Miller G. & Spoolman S, (2011), Cengage Advantage Books: Living in the Environment, Cengage Learning, U.S. Nag P, (2008), Power Plant Engineering, Tata McGraw-Hill Education, India National Research Council, (2001), Laying the foundation for space solar power: an assessment of NASA’s space solar power investment strategy, National Academies Press, U.S. Nomad4ever.com, (2012), Volcano Power instead of Nuclear would put Indonesia ahead in Green Energy Actions, available at http://www.nomad4ever.com/2008/06/30/volcano-power-instead-of-nuclear-would-put-indonesia-ahead-in-green-energy-actions/ Padiyar K, (1990), HVDC Power Transmission Systems: Technology and System Interactions, New Age International, India Rashid M, (2010), Power Electronics Handbook: Devices, Circuits, and Applications, Elsevier, U.K. Schernikau L, (2010), Economics of the International Coal Trade: The Renaissance of Steam Coal, Springer, Germany Sivanagaraju S, (2010), Generation and Utilization of Electrical Energy, Pearson Education, India Tewari J, (2003), Basic Electrical Engineering, New Age International, India UN, (2003), Water for people, water for life: a joint report by the twenty-three UN agencies concerned with freshwater, Berghahn Books, U.S. Wengenmayr R. & Buhrke T, (2011), Renewable Energy: Sustainable Energy Concepts for the Future, John Wiley & Sons VCH, Germany Read More