Phone Number : +8613408630944
WhatsApp : +8613408630944
October 14, 2020
Hydropower is a renewable energy source based on the natural water cycle. Hydropower is the most mature,reliable and cost-effective renewable power generation technology available (Brown, 2011). Hydropower schemes often have significant flexibility in their design and can be designed to meet base-load demands with relatively high capacity factors, or have higher installed capacities and a lower capacity factor, but meet a much larger share of peak demand.
Hydropower is the largest renewable energy source, and it produces around 16 % of the world’s electricity and over four-fifths of the world’s renewable electricity. Currently, more than 25 countries in the world depend on hydropower for 90 % of their electricity supply (99.3 % in Norway), and 12 countries are 100 % reliant on hydro. Hydro produces the bulk of electricity in 65 countries and plays some role in more than 150 countries. Canada, China and the United States are the countries which have the largest hydropower generation capacity (IPCC, 2011; REN21, 2011; and IHA, 2011).
Hydropower is the most flexible source of power generation available and is capable of responding to demand fluctuations in minutes, delivering base-load power and, when a reservoir is present, storing electricity over weeks, months, seasons or even years (Brown, 2011 and IPCC, 2011). One key advantage of hydropower is its unrivalled “load following” capability (i.e. it can meet load fluctuations minute-by-minute). Although other plants, notably conventional thermal power plants, can respond to load fluctuations, their response times are not as fast and often are not as flexible over their full output band. In addition to grid flexibility and security services (spinning reserve), hydropower dams with large reservoir storage be used to store energy over time to meet system peaks or demand decoupled from inflows.
Storage can be over days, weeks, months, seasons or even years depending on the size of the reservoir.
As a result of this flexibility, hydropower is an ideal complement to variable renewables as, when the sun shines or the wind blows, reservoir levels can be allowed to increase for a time when there is no wind or sunshine. Similarly, when large ramping up or down of supply is needed due to increases or decreases in solar or wind generation, hydro can meet these demands. Hydroelectric generating units are able to start up quickly and operate efficiently almost instantly, even
when used only for one or two hours. This is in contrast to thermal plant where start-up can take several hours or more, during which time efficiency is significantly below design levels. In addition, hydropower plants can operate efficiently at partial loads, which is not the case for many thermal plants.6 Reservoir and pumped storage hydropower can be used to reduce the frequency of start-ups and shutdowns of conventional thermal plants and maintain a balance between supply and demand, thereby reducing the load-following burden of thermal plants (Brown, 2011).
Hydropower is the only large-scale and cost-efficient storage technology available today. Despite promising developments in other energy storage technologies, hydropower is still the only technology offering economically viable large-scale storage. It is also a relatively efficient energy storage option.
The system integration capabilities of hydropower are therefore particularly useful for allowing the large-scale large penetration of wind and other variable power sources (IEA, 2010c). Systems with significant shares of large-scale hydro with significant reservoir storage will therefore be able to integrate higher levels of variable renewables at low cost than systems without the benefit of hydropower.
Hydropower can serve as a power source for both large, centralized and small, isolated grids. Small hydropower can be a cost-competitive option for rural electrification for remote communities in developed and developing countries and can displace a significant proportion of diesel-fired generation. In developing countries, another advantage of hydropower technology is that it can have important multiplier effects by providing both energy and water supply services (e.g. flood control and irrigation), thus bringing social and economic benefits. Hydropower is generally CO2-free in operation, but there are GHG emissions from the construction of hydropower schemes, from silting in the reservoirs and from the decomposition of organic material (predominantly an issue in tropical regions). Hydropower schemes can have an important spatial and visual footprint.
One of the greatest challenges with the development of hydropower is ensuring that the design and construction of hydropower projects is truly sustainable. This means that, in addition to an economic assessment, proper social and environmental impact assessments must be conducted and if there are negative impacts on local populations, ecosystems and biodiversity, these issues need to be mitigated in the project plan. In the past, this is an area where hydropower has had a poor track record in some cases.Some of the more important impacts that need to be considered and mitigated include changes in river flow regimes, water quality, changes in biodiversity, population displacement and the possible effects of dams on fish migration.Although hydropower technologies are mature, technological innovation and R&D into variable-speed generation technology, efficient tunnelling techniques. Hydropower projects account for an estimated half of all “certified emissions reduction” credits in the CDM pipeline for renewable energy projects (Branche, 2012).These can be direct (e.g. CO2 emissions from construction vehicles) or indirect (e.g. the CO2 emissions from the production of cement). The International Hydropower Association has a “hydropower sustainability assessment protocol” that enables the production of a sustainability profile for a project through the assessment of performance within important sustainability.integrated river basin management, hydrokinetics, silt erosion resistant materials and environmental issues (e.g. fish-friendly turbines) will provide continuous improvement of environmental performance and, in many cases, costs reductions (IPCC, 2011).