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Quoted By: candlemakerLast year one electricity generator admitted that for every 1MW of wind electricity penetrating the grid, there was at least 0.9MW of back-up operating.
Posted By: SteamyTeaNow I would never claim that for every MWh of renewable (remember that it is not unlimited) supplied there is a corresponding reduction in FF generation.
Posted By: jms452why is everyone so up in arms?
Posted By: SeretThe grid does operate a certain amount of spinning reserve and backup, but this isn't entirely to support wind as you need to cover faults and maintenance anyway, not to mention following demand.
Posted By: CWattersHow can the same spinning reserve be used for several purposes when they can easily occur at the same time?
Posted By: CWattersNobody is claiming that changes in output due to day to day changes in weather can't be predicted. What's more concerning are reports that rapid changes in total output are more frequent than expected..
Posted By: CWatters"The frequency of changes in output of 100MW or more over a five minute period was surprising.
Posted By: CWatters"The frequency of changes in output of 100MW or more over a five minute period was surprising. There is more work to be done to determine a pattern, but during March 2011, immediately prior to publication of this report, there were six instances of a five minute rise in output in excess of 100MW, the highest being 166MW, and five instances of a five minute drop in output in excess of 100MW, the highest being 148MW."
Posted By: jms452100MW change over five minutes is 1.2GW/hourTo put the concern into perspective the grid currently handles demand climbing by about 13 GW between 6.30am and 8.30am. That’s a slew rate of 6.5 GW/ hour.http://www.inference.phy.cam.ac.uk/withouthotair/c26/page_188.shtmlThe storage is a different matter but this is where the CCGT come in as a cheap interim solution.
Posted By: CWatters"The highest results in Fig 4 are from a study where four hour variability of wind (not forecast error), combined with load forecast error, results in 15 % reserve requirement at 10 % penetration and 18 % reserve requirement at 20 % penetration of gross demand"So somewhere between 1 and 18%.
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