Development of hydropower issues

Development of hydropower issues

1- Advantages

hydropower dam

a. Economics

The major advantage of hydropower is elimination of the fuel cost, immune to fossil fuels, such as oil, natural gas and coal with low construction and operating labor cost . The dam serves as multiple purposes.

b. Greenhouse gas emissions

Hydropower station does not burn fossil fuels, they do not directly produce carbon dioxide (a greenhouse gas). While some carbon dioxide is produced during manufacture and construction of the project, this is a tiny fraction of the operating emissions of equivalent fossil-fuel electricity generation.

c. Related activities

Reservoirs often provide facilities for water spots, and become tourist scenery.^. In some countries, using dam for irrigation can support the fish farm and water supply. Large hydropower station can control floods, and be used for transportation.

2- Disadvantage

a. Damage to the environment

pollutants at upstream of Three Gorges Dam

Hydropower projects can damage surrounding or downstream ecosystems of the plants. In some cases, dams have been demolished due to the impact on fish. It can lead to scouring of river beds and loss of riverbanks. In addition, it also has impact on birds. Since building dam for agricultural and energy use, many native and migratory birds have become increasingly endangered.

b. Population relocation

Hydropower station has the need to relocate the native people, whose history and culture sites may be flooded and lost. Such problems have arisen in the Three Gorges project.

3-Comparison with other methods of power generation

Compared to nuclear power, hydropower generates no nuclear waste and leaks. Unlike uranium, hydropower is a renewable energy resource. Compared to wind power, hydropower plants are predictable, which can be easily regulated in power demand. Compared to fossil-fueled power plants, hydropower stations take a long time to build. Unlike combustion turbines for fossil-fueled, which can be economically developed, hydropower production is limited; due to climate change Long-term energy production may be affected. Hydropower may incur additional cost to ensure availability of sufficient power in years lacking of water.

Hydropower project

       Types of Hydropower

There are three types of hydropower facilities: impoundment, diversion, and pumped storage. Some hydropower plants use dams and some do not. The images below show both types of hydropower plants. Impoundment The most common type of hydroelectric power plant is an impoundment facility. An impoundment facility, typically a large hydropower system, uses a dam to store river water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. The water may be released either to meet changing electricity needs or to maintain a constant reservoir level. Diversion A diversion, sometimes called run-of-river, facility channels a portion of a river through a canal or penstock. It may not require the use of a dam Pumped Storage When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity. Sizes of Hydropower Plants Facilities range in size from large power plants that supply many consumers with electricity to small and micro plants that individuals operate for their own energy needs or to sell power to utilities. Large Hydropower Although definitions vary, we define large hydropower as facilities that have a capacity of more than 50 MW. Medium Hydropower Although definitions vary, we define medium hydropower as facilities that have a capacity of 10 MW to 50 MW. Small Hydropower Although definitions vary, we define small hydropower as facilities that have a capacity of below 10 MW. Advantages and Disadvantages of Hydropower Hydropower offers advantages over other energy sources but faces unique environmental challenges. Advantages Hydropower relies on the water cycle, which is driven by the sun, thus it's a renewable power source. Hydropower is a fueled by water, so it's a clean fuel source. Hydropower doesn't pollute the air like power plants that burn fossil fuels, such as coal or natural gas. Hydropower is generally available as needed; engineers can control the flow of water through the turbines to produce electricity on demand. Hydropower plants provide benefits in addition to clean electricity. Impoundment hydropower creates reservoirs that offer a variety of recreational opportunities, notably fishing, swimming, and boating. Most hydropower installations are required to provide some public access to the reservoir to allow the public to take advantage of these opportunities. Other benefits may include water supply and flood control. Disadvantages Fish populations can be impacted if fish cannot migrate upstream past impoundment dams to spawning grounds or if they cannot migrate downstream to the ocean. Upstream fish passage can be aided using fish ladders or elevators, or by trapping and hauling the fish upstream by truck. Downstream fish passage is aided by diverting fish from turbine intakes using screens or racks or even underwater lights and sounds, and by maintaining a minimum spill flow past the turbine. Hydropower can impact water quality and flow. Hydropower plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian (riverbank) habitats and is addressed using various aeration techniques, which oxygenate the water. Maintaining minimum flows of water downstream of a hydropower installation is also critical for the survival of riparian habitats. New hydropower facilities impact the local environment and may compete with other uses for the land. Those alternative uses may be more highly valued than electricity generation. Humans, flora, and fauna may lose their natural habitat. Local cultures and historical sites may be impinged upon. Some older hydropower facilities may have historic value, so renovations of these facilities must also be sensitive to such preservation concerns and to impacts on plant and animal life.

XIANGJIABA hydropower station

Xiangjiaba hydropower station

China's third largest hydropower station

-XIANGJIABA  hydropower station

Project total investment:43.4 Billion Yuan

 Engineering period: 2008-2015

Xiangjiaba hydropower station located in downstream of Jinsha river, Yuannan Fushui county (right bank) and Sichuan Yibin County (Left Bank) . Where is the junction of the two provinces. 157km away from Xiluodu hydropower station. Static investment 43.4 billion Yuan.

Xiangjiaba hydropower station installation capacity 6000 megawatt,( total 8 unit, each one 750 megawatt), reservoir normal storage water level 380m,guarantee output power 2.009 million KW, average annual generating capacity of 30.747 billion KWH. reservoir area 95.6 sq.km, the reservoir is gorge type, total reservoir volume 5.163billion cubic meter. Backwater length 156.6 km. control drainage area 458.8 thousand sq.km. 97% of Jinsha river drainage area.

The project closure on 2008, and the first unit put into operation on 2012, complete project finished on July.2014.

The project use gravity dam, crest elevation 383m, crest length 909.3m, max. Dam height 161m.

Xiangjiaba hydropower station also use vertical Francis hydro turbine, installed 8 unit 800MW turbine generator set. it has the world largest unit installed capacity Francis turbine generator, also the first 800MW Francis turbine generator in the world.

The turbine key parameter below:(world's largest hydro turbine)

Installed capacity:8x800MW,

Max. Water head: 114.2m,

Min.water head:86.1m,

Rated water head: 100m

Runner inlet diameter:10360mm

Runner outlet diameter: 9300mm

Runner max. Diameter:10527mm

Rated output power:812MW

Turbine rated speed:71.4r/min

XILUODU hydropower station

China's second largest hydropower station

-XILUODU hydropower station

Project total investment:79.2 Billion Yuan
Engineering period: 2005-2015

Xiluodu hydropower station is located in Qinghai-Tibet Plateau, Yunnan-Guizhou Plateau to the Sichuan Basin transition zone, located in Xiluodu Gorge, where bordering Leibo County, Sichuan Province and Yongshan County, Yunnan Province,  Xiluodu Hydropower Station is the largest of the four giant hydropower station on Jinsha River, Capacity quite with the Itaipu,the world's second largest hydropower station.total installed capacity is 12.6 million kilowatts, Annual generation capacity ranked third in the world,is 571.2 billion KWh, equal to Itaipu hydropower station, and three and a half of the Gezhou Dam, is the second largest hydropower station in China.

Xiluodu hydropower station is the closest key power of China “west to east power transmission project” on Jinsha river, also the largest hydropower station on Jinsha river.

Jinsha river is upper stream of Yangtze river,total length 3364 kilometer, drainage area 473.2 thousand sq.km. Jinsha river has abundant water resources, reserves energy reached 112.4 million kilowatts,  accounted for 1/6 of the total hydropower in China.

This project located in Xiluodu Gorge, where bordering Leibo County, Sichuan Province and Yongshan County, Yunnan Province, downstream of Jinsha river. The project use concrete double curvature arch dam,dam height 278m, normal storage water level 600m, total storage 11.57 billion cubic meters,

Regulation storage 6.46 billion cubic meters, installed capacity 12.6 million KW, average annual generating capacity of 57.12 billion KWH, the project static investment 45.928 billion Yuan, total 79.234 billion Yuan. Project feasibility design finished on Dec. 2001, start building on Dec.2005, on Jun.2013, the first set of generator put into operation, and whole project completed on 2015.

Xiluodu Hydropower station use vertical Francis hydro turbine, manufacturer Voith, rated water head 197m, max. Head 229.4m, min. Head 154.6m, weighted average of the head 223.48m, rated flow 430.5 cubic meter per second, rated output power 784 Megawatt, rated speed 125 r/min,suction head HS=-10.81m, installation elevation 359m. Francis runner diameter is 7.4m, max. Outer diameter 7.755m, height 3.462m, each runner weight 179 ton.

Material is stainless steel 0Cr13Ni4Mo.  

  

When Xiluodu hydropower plant was fully connected to the grid in June 2014, it started with a nominal capacity of 13.86 gigawatts. All in all, 18 machine units are in operation. This made it the world's third largest hydropower plant. The plant will help to reduce air pollution thanks to the renewable electricity production of Xiluodu: The annual consumption of coal will be cut down by 41 million tons. In addition to that, exhaust gas emissions will be reduced by nearly 150 million tons of CO2, 480,000 tons of nitrogen dioxide and 850,000 tons of sulfur dioxide per year.

Another advantage of Xiluodu is the ability to deliver base load in large quantity. Xiluodu can produce as much energy around the clock as 14 large thermal or nuclear power plants. As a matter of fact, hydropower technology can bridge the gap between the enormous demand of electricity, and, on the other hand, meet the emission targets our societies have committed themselves to.

panoramic photo of Construction site:

Closure photo of the Xiluodu Dam

Dam photo:

 Spiral case photo:

 spiral case welding:

 Draft tube tunnel construction

 spiral case installation

 Francis turbine runner

 generator rotor isntallation

 generator stator assembly

night scene of XILUODU

Three Gorges Hydropower Project

In 2012, the Three Gorges Dam in China took over the #1 spot of the largest hydroelectric dam (in electricity production), replacing the Itaipu hydroelectric power plant in Brazil and Paraguay. The Three Gorges Dam has a generating capacity of 22,500 megawatts (MW) compared to 14,000 MW for the Itaipu Dam. But, over a year-long period, both dams can generate about the same amount of electricity because seasonal variations in water availability on the Yangtze River in China limit power generation at Three Gorges for a number of months during the year.

The height of Three Gorges is about 594 feet (181 meters (m)) and the length is about 7,770 feet (2, 335 m). The dam creates the Three Gorges Reservoir, which has a surface area of about 400 square miles (1,045 square kilometers) and extends upstream from the dam about 370 miles (600 kilometers).

In the United States, the Grand Coulee Dam on the Columbia River, Washington, is the largest, with a generating capacity of about 6,800 MW (5th overall worldwide).

Three Gorges power station had installed 32 units of 700MW turbines,which is the largest capacity, largest size of Francis generator set. The Francis turbine runner diameter is 10.05m,height 5.99m, total weight 445 ton, 15 blades, each blades weight 17.6 ton. The runner use stainless steel 0Cr13Ni4Mo, weld structure. The turbine design water head 85m.