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End of Nuclear Power Generation
blubart:
@Burkingam: even assuming the water volume is equally distributed over all levels (which is obviously not true simply due to the way a dam is build) the build up water at peak levels should be sufficient to easily double, likely even triple the output in the winter months without loosing much efficiency or even remotely coming near the minimum water level. i'm not sure what calculations you did. in addition the numbers in the graph are distorted simply by the fact that the first time the dam was actually filled was in october 2010!! - everything before that the dam was not able to work at full efficiency. the graph shows the 2008 values.
@Bob2004: the graph would be true for your argument if three gorges would be a run-of-the-river hydroelectric plant - it's *surprise* a dam though.
which means that you have a considerable headroom of ~35m water level to work with. in the winter season you can lower the water level to produce more energy than what the river flow supplies (that's what the graph is really showing) knowing that in the summer (especially the flood season) the reservoir will be refilled.
not to mention that the peak of the dams power output follows the yearly peak of electric power consumption.
in your definition of "reliable" nuclear reactors are just as bad, as their energy output is only slowly scalable - thus nuclear plants will never be able to compensate for hourly fluctuations in energy demand requiring you to run other plants for everything but the base load.
Burkingam:
@blubart I simply divided the plan reservoir capacity 39.3 km3 (39,300,000,000m3) in 180 days. The result is about 2500m3/s. This graph shows the average water input from the river.
(click to show/hide)If we only spread is over 90 days we can double the energy output but we are still far from a stable energy source. Additionally, energy demand will be higher during winter. Bob2004's point is still valid. The problem is still there. I'm not stubborn. When I'm debating something and someone makes a valid point against my thesis I grant it. That's what I did with Bob2004.
On another hand, since water input is smaller during winter, it means the plant will provide a better protection against flood during spring (because it can stockpile excess water in the now empty reservoir). So I guess it's not all bad.
blubart:
--- Quote from: Burkingam on June 14, 2011, 01:07:20 AM ---@blubart I simply divided the plan reservoir capacity 39.3 km3 (39,300,000,000m3) in 180 days. The result is about 2500m3/s. This graph shows the average water input from the river.
(click to show/hide)If we only spread is over 90 days we can double the energy output but we are still far from a stable energy source. Additionally, energy demand will be higher during winter. Bob2004's point is still valid. The problem is still there. I'm not stubborn. When I'm debating something and someone makes a valid point against my thesis I grant it. That's what I did with Bob2004.
--- End quote ---
ups - i must have misplaced a decimal point somewhere in the calculation - after redoing it i only got a 30% increase using the production limits, not a 300% one -.-
actually the electrical energy demand tends to spike in summer (with a smaller spike in winter) - heat should always be produced separately or as part of a cogeneration process anyway as the efficiency of the heat -> electricity -> heat conversion process is just to low.
it's obvious that hydro electricity can not be the only source for electricity to depend on, but it has the same variability as fossil fuel plants in terms of instant scalability - something nuclear plants can't which makes them in the context of loosing the dependency on fossil fuels pretty much obsolete. our power consumption is not "stable" so our energy source does not necessarily need to either.
without the development of energy storage systems nuclear can not act as a bridge technology to get rid of fossil plants now until renewable energy is established - and if we had those storage systems solar and wind power would be just as "stable" as nuclear.
Burkingam:
Of course we can have countries 100% powered by hydro. But that's not possible everywhere.
It's actually very hard to start or stop coal plants so it's not an adequate source for load balancing. Gas is often used for that but hydro is the best for that as it's very easy to stop it. Some Plants even have pumps to store additional water from a lower reservoir to a higher reservoir when there is excess energy produced by other plants. It's called Pumped-storage_hydroelectricity. It has the highest capacity to store energy of all current storage technologies. It's great to complement harder to control energy sources, like wind.
Bob2004:
--- Quote from: Burkingam on June 14, 2011, 04:29:32 PM ---Of course we can have countries 100% powered by hydro. But that's not possible everywhere.
It's actually very hard to start or stop coal plants so it's not an adequate source for load balancing. Gas is often used for that but hydro is the best for that as it's very easy to stop it. Some Plants even have pumps to store additional water from a lower reservoir to a higher reservoir when there is excess energy produced by other plants. It's called Pumped-storage_hydroelectricity. It has the highest capacity to store energy of all current storage technologies. It's great to complement harder to control energy sources, like wind.
--- End quote ---
But the problem with hydro plants is that there are so few places suitable for building a reasonable sized one, let alone one with multiple reservoirs for storing extra water. There's pretty much nowhere where a decent size dam could be built in the UK, for example, where I live. The same can be said for countries like the Netherlands which are very flat - and most of the few suitable locations in mainland Europe already have dams in place. In a country like Canada which has vast swathes of uninhabited mountainous areas, there is a lot more potential for building hydroelectric dams than in most of the rest of the world.
Nuclear plants are well suited for providing the bulk of a nation's power precisely because they do not need to be turned on and off to do so. The bulk of a nation's power generation does not need to be particularly scalable, since it is in use all year round; the increased power use in summer and winter can then be efficiently handled by more scalable technologies such as hydro or gas which can be easily shut down when not needed.
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