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"conventional" hydro is not a very precise adjective: https://www.hydropower.org/types-of-hydropower obviously it is not run-of-river, but storage hypdropower with a large reservoir |
moving two paragraphs to the section on "complementary power sources and matching demand" |
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The use of intermittent sources in an electric power system usually displaces storable primary energy that would otherwise be consumed by other [[power station]]s. Another option is to store electricity generated by non-dispatchable energy sources for later use when needed, e.g. in the form of [[pumped storage]], [[Compressed_air_energy_storage|compressed air]] or in [[Battery (electricity)|batteries]]. A third option is the [[sector coupling]] e.g. by electrode heating for district heating schemes.
In the past electrical generation was mostly dispatchable and consumer demand led how much and when to dispatch power. The trend in adding intermittent sources such as wind, solar, and run-of-river hydro means the grid is beginning to be led by the intermittent supply from RES harvesting instead. The use of intermittent sources relies on electric power grids that are carefully managed, for instance using highly dispatchable generation that is able to shut itself down whenever an intermittent source starts to generate power, and to successfully startup without warning when the intermittents stop generating.<ref>US Department of Energy: [https://www.energy.gov/sites/prod/files/2017/01/f34/Maintaining%20Reliability%20in%20the%20Modern%20Power%20System.pdf Maintaining Reliability in the Modern Power System], December 2016, p. 17</ref> Ideally the capacity of the intermittents would grow to be larger than consumer demand for periods of time, creating excess low price electricity to displace heating fuels or be converted to [[Energy storage|mechanical or chemical storage]] for later use. ▼
The displaced dispatchable generation could be lignite, hard coal, natural gas, biomass, nuclear, geothermal or storage hydro. Rather than starting and stopping nuclear or geothermal it is effective to use them as constant [[base load]] power, when that power is not needed it can displace heating fuels or be converted to storage for later use. Biofuels and hydro can be saved for later when intermittents are not generating power. [[Fossil fuel phase-out|Alternatives to burning]] coal and natural gas with the production of [[greenhouse gas]]es may eventually make them a [[stranded asset]] that is left in the ground. Highly integrated grids favor flexibility and performance over cost, resulting in more plant capacity and lower [[capacity factor]]s.<ref>https://www.treehugger.com/renewable-energy/death-capacity-factor-how-wind-solar-ultimately-win-game.html</ref>▼
The use of small amounts of intermittent power has little effect on [[Electrical grid|grid]] operations. Using larger amounts of intermittent power may require upgrades or even a redesign of the grid infrastructure.<ref name='All_Island_Grid_Overview'>{{cite web|url=http://www.dcenr.gov.ie/NR/rdonlyres/E20F6E3D-8724-4E39-B315-0670B8C9841E/0/AllIslandGridStudyStudyOverviewJan08a2.pdf |title=All Island Grid Study |accessdate=2008-10-15 |date = January 2008| pages=3–5, 15 |format=PDF |work=Department of Communications, Energy and Natural Resources }}</ref><ref name='CarbonDTI'>{{cite web|url=http://www.ensg.gov.uk/assets/ct_impact_of_re_final_report.pdf |archive-url=http://webarchive.nationalarchives.gov.uk/20100919181607/http://www.ensg.gov.uk/assets/ct_impact_of_re_final_report.pdf |dead-url=yes |archive-date=2010-09-19 |title=The Carbon Trust & DTI Renewables Network Impacts Study |accessdate=2009-04-22 |date = January 2004 |orig-year=commissioned June 2003 |format=PDF |work=Carbon Trust and UK Department of Trade and Industry }}</ref>
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===Complementary power sources and matching demand===
▲In the past electrical generation was mostly dispatchable and consumer demand led how much and when to dispatch power. The trend in adding intermittent sources such as wind, solar, and run-of-river hydro means the grid is beginning to be led by the intermittent supply from RES harvesting instead. The use of intermittent sources relies on electric power grids that are carefully managed, for instance using highly dispatchable generation that is able to shut itself down whenever an intermittent source starts to generate power, and to successfully startup without warning when the intermittents stop generating.<ref>US Department of Energy: [https://www.energy.gov/sites/prod/files/2017/01/f34/Maintaining%20Reliability%20in%20the%20Modern%20Power%20System.pdf Maintaining Reliability in the Modern Power System], December 2016, p. 17</ref> Ideally the capacity of the intermittents would grow to be larger than consumer demand for periods of time, creating excess low price electricity to displace heating fuels or be converted to [[Energy storage|mechanical or chemical storage]] for later use.
▲The displaced dispatchable generation could be lignite, hard coal, natural gas, biomass, nuclear, geothermal or storage hydro. Rather than starting and stopping nuclear or geothermal it is effective to use them as constant [[base load]] power, when that power is not needed it can displace heating fuels or be converted to storage for later use. Biofuels and hydro can be saved for later when intermittents are not generating power. [[Fossil fuel phase-out|Alternatives to burning]] coal and natural gas with the production of [[greenhouse gas]]es may eventually make them a [[stranded asset]] that is left in the ground. Highly integrated grids favor flexibility and performance over cost, resulting in more plant capacity and lower [[capacity factor]]s.<ref>https://www.treehugger.com/renewable-energy/death-capacity-factor-how-wind-solar-ultimately-win-game.html</ref>
* Electricity produced from solar energy could be a counterbalance to the fluctuating supplies generated from wind. In some locations, it tends to be windier at night and during cloudy or stormy weather, so there is likely to be more sunshine when there is less wind.<ref name='AtlanticFragility'>{{cite web|url=http://www.rmi.org/images/other/EnergySecurity/S83-08_FragileDomEnergy.pdf |title=The Fragility of Domestic Energy |accessdate=2008-10-20 |last=Lovins |first=Amory |author2=L. Hunter Lovins |date = November 1983|format=PDF |work=The Atlantic |archiveurl = https://web.archive.org/web/20080625205941/http://www.rmi.org/images/other/EnergySecurity/S83-08_FragileDomEnergy.pdf |archivedate = June 25, 2008}}</ref>
* In some locations, electricity demand may have a high correlation with wind output, particularly in locations where cold temperatures drive electric consumption (as cold air is denser and carries more energy).
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