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Hydropower
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
Although the main focus of this section has been on large-scale hydropower, as we have seen, the spectrum of scales for the production of hydroelectricity is vast, and for some applications, hydro on a very small scale may be quite useful—either in remote rural communities in developing nations or for individual homeowners. In fact, on a worldwide basis, the contribution of small hydro is substantial (85 GW) with over 70% of that in China alone. Small hydro is usually defined as P < 10–50 MW, but it is also sometimes further subdivided into minihydro (P < 1 MW), microhydro (P < 100 kW), picohydro (P < 5 kW), and even nanohydro (P < 200 W). A turbine in the pico category might be suitable either for one American home or as many as 50 homes in a remote rural community in a developing nation where one or two fluorescent light bulbs and a radio might otherwise not be possible. One way to generate electricity on the nanoscale makes use of the simple Pelton turbine. This may seem surprising, since earlier, it was noted that Pelton turbines were unsuited to sites with small values of the head. However, very low-power applications are the exception to that rule. For example, using the same design restrictions that were used to generate the results in Table 8.1, it is easy to show that for a nanohydro application where we wish to generate 100 W, and a site where the head is a mere 1 m, we find perfectly acceptable values for the turbine speed (151 rpm) and radius (0.14 m).
Water resources science
Published in Mohammad Albaji, Introduction to Water Engineering, Hydrology, and Irrigation, 2022
Water is used in power generation. Hydroelectricity is electricity obtained from hydropower. Hydroelectric power comes from water driving a water turbine connected to a generator. Hydroelectricity is a low-cost, non-polluting, renewable energy source. The energy is supplied by the sun. The heat from the sun evaporates water, which condenses as rain in higher altitudes, from where it flows down.
Energy and Environment
Published in T.M. Aggarwal, Environmental Control in Thermal Power Plants, 2021
Energy in water can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy. There are many forms of water energy: Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. The largest of which is the Three Gorges Dam in China and a smaller example is the Akosombo Dam in Ghana.Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a remote-area power supply (RAPS).Run-of-the-river hydroelectricity systems derive kinetic energy from rivers and oceans without the creation of a large reservoir. Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 per cent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 per cent of domestic electricity use. There are now three hydroelectricity plants larger than 10 GW: the Three Gorges Dam in China, Itaipu Dam across the Brazil/Paraguay border, and Guri Dam in Venezuela.
Integrative technology hubs for urban food-energy-water nexuses and cost-benefit-risk tradeoffs (I): Global trend and technology metrics
Published in Critical Reviews in Environmental Science and Technology, 2021
Ni-Bin Chang, Uzzal Hossain, Andrea Valencia, Jiangxiao Qiu, Qipeng P. Zheng, Lixing Gu, Mengnan Chen, Jia-Wei Lu, Ana Pires, Chelsea Kaandorp, Edo Abraham, Marie-Claire ten Veldhuis, Nick van de Giesen, Bruno Molle, Severine Tomas, Nassim Ait-Mouheb, Deborah Dotta, Rémi Declercq, Martin Perrin, Léon Conradi, Geoffrey Molle
As a potential renewable energy, run-of-the-river hydroelectricity is a typical type of hydropower that harvests the energy from flowing water to generate electricity via an impoundment facility. However, tidal power can also convert kinetic hydro-energy into power. With the rapid advancement of this technology, tidal energy potential has been estimated to be about 32 PWh/year globally (Rusu & Venugopal, 2019). Due to its huge potential, the European Union has planned to install capacities of 3.6 GW and 188 GW by 2020 and 2050, respectively (Segura et al., 2017). Since tidal energy technologies are still in an initial stage of development, environmental impact, cost-benefit, technological viability, and potential risks are yet to be thoroughly studied, although some successful cases have been reported (Segura et al., 2017). Several technology variations have been reported to provide cost-effective energy generation (shown in Supplementary Information Table S4). Some of these technologies may be considered centralized technology. Descriptions of hydro-power technologies such as tidal barrage (T2-TB), dynamic tidal power (T3-DTP), stream generator (T1-SG) and wave energy to power (T4-WtP) are given in Supplementary Information (S1.1), and the associated costs, benefits, and risks are shown in Table S4 (Supplementary Information).
Parametric study of a proposed small hydropower project at Gurara-Nigeria
Published in Cogent Engineering, 2021
Moses E. Emetere, Oluwaseyi Bello, S.A. Afolalu, A.O. Mamudu, L.M. Amusan, C.O. Iroham, I. Odun-Ayo
Geothermal energy is obtained from the heat in the earth; geothermal energy is renewable because it is inexhaustible – it cannot finish. This form of energy provides more electricity than solar energy and about the same as wind energy. It is not expensive and does not pollute the environment—it is environmentally friendly. Unlike solar and wind energy, it is not dependent on the nature of the weather. Another alternative energy sources that do not depend on the weather are hydroelectric energy. Hydro generally means water; therefore, hydroelectric energy is the energy obtained by the force of water that is energy from waterpower. When using hydroelectricity, the kinetic energy from the falling water is converted to electricity. This form of energy reduces the emission of greenhouse gases (Gulliver John & Arandt Roger, 1991).
High-load domestic wastewater treatment using a combined anaerobic-aerobic bio-filter with coal cinder as medium
Published in Environmental Technology, 2018
Yaoxing Liu, Yuxin Lei, Yin Xi, Zaiyi Liao, Xia Zhang
Currently, more than 96% of domestic wastewater is discharged directly into the environment with no treatment in rural areas of China [1]. The Three Gorges Dam, constructed on the Yangtze River in China, is the largest hydroelectricity project in the world. When the dam was constructed, most of the industrial plants vacated this area in order to protect the water quality of the reservoir. Since 2003, however, annual algal blooms appeared in the Three Gorges Reservoir (TGR) following impoundment [2,3]. This was mainly attributed to deterioration of water quality induced by the discharge of non-point-source pollutants from agriculture, rural wastewater, street runoff, and atmospheric deposition. Among the non-point sources, domestic wastewater is a main source of pollutants in rural areas near the TGR. Thus, in order to protect the water quality of the TGR, domestic wastewater needs to be treated before being discharged.