能动专业英语part_3_Hydropower

115 Part Three Hydropower Unit One Hydropower Development Around the World The contribution of hydro power to modern society is significant and continues to grow supporting economic and social development worldwide Nevertheless there is an enormous diversity of conditions of hydropower use and visions for the future North America and Europe use over 80 of their hydropower potential but on the other extreme Africa uses 3 with these differences reflecting respective economic development Hydro contributes 17 of the total world electricity production with hydroplants in some 150 countries and 24 of these countries depend on it for 90 of their electricity supply The major hydrocountries are shown in Figure 3 1 Hydroelectricity recently began to be in the spotlight because of two completely opposite views On one hand supporters quote its clean energy production characteristics which are an attractive attribute in an emission constrained world On the other hand the international antidam lobby demands that major hydro developments be stopped altogether Figure 3 1 Major hydro producers in 2004 1 Phases of Hydro Development Development of hydrogeneration worldwide has progressed through three main phases since the late 19th century These phases correlate directly with the type of projects selected for development and the resources available for implementation such as rivers mountains and precipitation Phase I can be thought of as the birth of modern power systems and comprises the time from the first development of the electric generation industry through to the late 1930s This period was characterized by project development by largely private sector utilities and industrial companies to meet immediate demands Financing was limited and projects were developed as needed often for specific industrial ventures in the developing world The configuration and capacity of the projects 116 considered were driven by economic and technical factors usually leading to modest scale projects that could be financed from the resources of the relatively small utilities in existence at that time Phase II was ushered in by the recession of the 1930s and the rapid economic growth and industrialization following World War II The recession first led some governments to intervene to develop some large hydroprojects like the Tennessee Valley Authority and the Bonneville Power Administration in the United States or create state agencies to drive investment in power supply as in Canada and several other countries around the world Further on industrialization expanded energy use significantly as development spread internationally The growth rate promoted by economic planners exceeded the capability of the nascent private utilities to finance the required generation expansion Accordingly many governments took further direct roles in the power sector through the formation and or expansion of publicly owned utilities In the developing world the major financing needs in this period were supported by the multilateral financing agencies During the 1960s and 1970s utilities embarked on programs of building large projects supported by government financing resources in an effort to keep pace with an increasing demand to foster development in emerging economies Projects were designed to meet several needs including water supply flood control and irrigation as well as power generation and were intended to be national development engines in addition to the simple purpose of generation In the present Phase III that has evolved during the last 15 years the world has in many ways returned to the development model used during the emerging years of the power industry This can be characterized by market driven investments as the economies move away from the centralized nationalized structures that were artifacts of the mega project phase in the 1960s and 1970s One of the most important elements driving this transition is the realization mainly in the developing world that foreign direct investment can be an important source of financing the large capital requirements of power sector expansion Multilateral financing has ensured that many nations have matured politically and commercially so that large scale foreign investment is viable This phase has several variants and the extent to which each country has moved down the road of market driven investment governs investment strategy adopted by private power developers Today energy sales from independent power projects use various vehicles ranging from direct power purchase agreements with a utility at the outset of privatization to a sophisticated power pool or merchant market in the more developed markets 2 Hydro Challenges A significant change has occurred in the professional orientation and background of hydropower development proponents particularly during the last decade It is well known that hydroengineering has reached a level of sophistication and maturity such that given previous experience in the development of hydro most technical difficulties of hydro implementation are well understood and can be solved at a price The main difficulties pertain to accurately forecasting and quantifying the risks and associated costs of each individual project Numerous factors control whether and to what extent private funding is available for the support of hydropower project development throughout the world One of the difficulties with attracting private investment and finance to hydropower projects is the need for a higher return on equity than was traditionally sought by utilities and the multilateral agencies Much of the criticism of hydropower centers on the environmental effects of large reservoirs 117 and in particular the problems of resettlement The general guideline has been that the smaller the reservoir the more likely the project is to be environmentally friendly Developers and financial institutions recognize the importance of this aspect of project development and environmental and resettlement issues are always in the list of factors when projects are subject to preliminary assessment of viability 3 Hydropower Progress The hydropower progress in several regions of the world is different South America where hydro development is very active the United States and Canada where the greatest portion of the hydro potential has already been explored China a fast growing market with significant hydro resources and Africa with still a large potential unexplored Some articles will cover the state of development of hydroelectricity in its region Potential for growth specific projects environmental constrains and economics are a few of the issues that will be covered with articles encompassing diverse flavors around the globe The primary challenge faced by South American countries is to ensure sufficient capacity and investment in electricity infrastructure to serve reliably their growing economies currently faced with shortages and high prices Within those conditions the development of vast unexploited hydroelectric resources particularly in Brazil is at the center of attention where its renewable character is being confronted with its environmental impact Canada and the United States are world leaders in hydropower Among the first countries to develop hydropower facilities in the 1880s they are today in the top four producing countries Hydropower is the largest renewable energy resource in the United States accounting for more than three quarters of all existing renewable energy capacity in the country Opportunities for growth in every part of the U S hydropower sector even with existing conventional hydropower dams where new technologies that improve efficiency could in the next 20 years add up to approximately 2 300 MW the equivalent of two large sized coal or nuclear power plants Regarding Canada from the late 1880s onward hydropower has been developed to the extent that like the national railway it helped to define Canada opening up remote regions attracting industries and stimulating economic growth Canada generates now close to two thirds of its electricity with water The role that hydropower can play in reducing greenhouse gas emissions is emphasized by powering cars trains and subways and by replacing the burning of coal and natural gas for electricity generation In China the energy shortages that have occurred in the recent past affecting the country s economic development and its social life This reflects on the need to install more than 100 GW annually in 2006 and 2007 mostly from coal fired thermal power plants that are the main sources of pollution in the country This has made it evident that the future lies in the exploitation of more hydro power more nuclear power and other clean and sustainable energy resources with a potential hydropower capacity of 676 GW Flood control and environmental and agricultural benefits are to be balanced with the need to displace significant numbers of people Finally the continent in the dark as Africa has been described because of its lack of enough electricity Africa s exploitable hydroelectric potential is estimated at approximately 1 4 million GWh year which is sufficient to supply electricity for the entire continent but only 3 of this hydroelectric potential is available Therefore hydropower development is a major goal in Africa Matters of concern in the exploitation of its hydropower potential are the poor integration of 118 technical data with demographic socioeconomic and environmental data corruption and conflict Nevertheless there is a declared will to work toward addressing and overcoming these obstacles in an energy thirsty continent Reading material Hydropower in China China is one of the largest countries in the world with an area of about 9 6 million km2 and a population of about 1 3 billion in 2007 Its electricity generation and consumption have increased significantly in the past half century In 1949 the total generation installed capacity was 1 850 MW including 163 MW of hydropower By the end of 2007 the total installed capacity had reached 713 29 GW and the total annual generation production had reached 3 255 9TWh Both of these numbers rank second in the world The percentages of hydro thermal and nuclear in total generation capacity and total annual generation production are shown in Figure 3 2 a and Figure 3 2 b respectively However the electricity supply in China mainly relied on coal fired thermal power plants by now The issues of power industry development in China concern three aspects as follows First the rapid economic growth requires adequate electricity supply It is a challenge for the power industry to catch up to the quickly increasing electricity demand From 2004 to 2007 the installed capacity has increased from 440 GW to 713 GW However the electricity supply still cannot satisfy the requirement of fast economic growth Energy shortages have occurred from time to time Especially in 2003 2005 China had experienced the most serious energy shortages of which 24 provinces had electricity rations The total electricity shortage was about 30 40 GW The electricity shortage has affected the economic development and social life This situation was alleviated in 2006 and 2007 after installing more than 100 GW each year Figure 3 2 a Percentage of hydro thermal and nuclear installed capacity in 2007 b Percentage of hydro thermal and nuclear generation production in 2007 Second electricity generation is dominated 83 in 2007 by coal fired thermal power plants which cause environmental problems The emission of CO2 SO2 NOx and pollutants from coal fired thermal power plants is one of the main sources of pollution in the country On the other hand the coal price volatilities may affect electricity generation Third a large part of the thermal capacities are small thermal units whose efficiencies are lower compared to large scale power plants Most of the small coal fired units are old units without emission control technologies For 1KWh of energy produced small old coal fired power plants would consume more coal and produce more pollution All of these issues call for the 119 exploitation of more hydropower more nuclear power and other clean and sustainable energy resources 1 Hydropower Resources China has abundant water resources for hydropower The potential hydropower capacity is 676GW and the potential annual generation of hydropower is 5 920TWh Among these the exploitable capacity of hydropower is 378GW and the exploitable annual generation of hydropower is 1 920TWh The potential capacity and exploitable capacity of hydropower in China are shown in Figure 3 3 Three provinces autonomous regions Sichuan Xizang Tibet and Yunnan have the most abundant hydro power resources which are 22 20 and 19 of the total exploitable hydropower capacity The water resources are concentrated in three drainage basins the Changjiang River or Yangtze River basin the Yellow River basin and the Yaluzangbu River upper reach of Brahmaputra River India basin The exploitable hydropower capacities of the three drainage basins are respectively 47 13 and 7 of the total exploitable hydropower capacity The other large river basins include the Lancangjiang River upper reach of Menam Khong River Laos and the Nujiang River upper reach of Thanlwin River Myanmar 2 Hydropower Projects The first hydropower plant in China the Shilongba hydropower station was built in April 1912 in Kunming Yunnan The capacity was only 480 KW After that hydropower developed significantly and reached 145 26GW in 2007 The installed capacities of hydro thermal and the total installed capacity from 1949 2007 are shown in Figure 3 4 Figure 3 3 Exploited and exploitable hydropower in China Notes The circled areas indicate the exploitable hydropower in each province The red pie sectors indicate the portion of exploited hydropower to exploitable hydropower of the province It can be seen from Figure 3 4 that the growth of hydropower capacity became faster after the 1990s Before the 1980s most of the hydro stations were small and medium sized stations 100 kW to 50 MW concentrated in the eastern part of China It was very common to build the small 120 run of the river systems for agriculture and electric power supply The large capacity hydropower projects started in 1990s including the famous Three Gorges Hydroelectric Project which is the world s largest hydropower project In fact the planning survey and feasibility analysis of the Three Gorges Hydroelectric Project started way back in the 1950s The preliminary proposal was submitted to the State Council for approval After eight years of discussions and fierce debates in the State Council and People s Congress this project was finally approved in 1992 The construction work started in December 1994 The total installed generation capacity of the Three Gorges hydro station is 22 400 MW including 14 700 MW in the Left Bank Station 12 700 MW in the Right Bank Station and 6 700 MW in the underground Station Now the 14 generators in the Left Bank Station have already started generating electric power as well as some of the generators in the Right Bank Station The whole project will be completed in 2009 The height of the dam is 181 m and the capacity of the reservoir will be 16 5 million m3 Some other large hydropower projects under constructions are listed in Table 3 1 Sites of large hydro projects in operation and under construction are shown in Figure 3 5 Figure 3 4 Installed capacities of hydro and thermal and the total installed capacity in China 1949 2007 Table 3 1 Large hydro projects under construction Project Name RiverProvince Capacity MW Construction Started River Closure Unit in Operation Last Unit in Operation XiluoduYangtzeYunnan Sichuan12 6002003200820142018 XingjiabaYangtzeSichuan6 0002005200820122015 Jinping 1st Cascade YalongjiangSichuan3 6002005200620122014 Jinping 2nd Cascade YalongjiangSichuan4 4002007 20132015 PubugouDaduheSichuan3 3002004200520092011 GoupitanWujiangGuizhou3 0002003200420092011 LongtanXijiangGuangxi5 4002001200320072009 XiaowanLancangjiangYunnan4 2002002200420092011 NuojiaduLancangjiangYunnan5 8502005200820142017 LawaxiYellow riverQinghai4 2002003200420102013 Total52 550 121 Figure 3 5 Sites of large hydro projects in operation and under construction in China 3 Benefits and Challenges of Hydro Projects 1 Flood Control Besides electric power generation the major benefit of these hydropower projects in China is flood control The Yellow River is probably the most flooding river in the world There have been thousands of flooding disasters in its history However after constructing 13 cascading hydro stations along the river in about half a century there has been no flood in Yellow River since 2000 The Three Gorges Dam also helped to alleviate flooding in the middle reaches of Yangtze River However to mitigate the damage of the most serious flood which occurs once per 100 years China still has a lot of work that needs to be done 2 Environmental Benefits China ranks second for CO2 emission after the United States and SO2 emission in the world Just imagine if without the Three Gorges hydro station China would instead build thermal power plants of 22 400 MW to support the economy growth This would produce more pollution and cause more acid rains not only in China but also may pollute the air and water in neighboring countries 3 Agriculture Benefits from Small Hydropower Until 2005 China had built 33 000 MW of small hydro stations in rural areas which brought electricity to 500 million people who had no electricity in their homes before The small hydro projects also bring benefits for agriculture irrigation 4 Sediment Problem The upper Yellow River flows through several desert areas The sediments are transported to the lower Yellow River basin and deposited on the riverbed whose altitude becomes higher year by year The sediments have to be removed otherwise the hydro stations in the middle reach will be b