Remind me why hydroelectric energy is considered "good energy"?

What kind of energy is "good" to you? Wind kills birds, hydroelectric hurt fish, fossil fuels kill everything, Solar?

 

Hydroelectric does have some carbon footprint (the decaying vegetation in the new lake). Fish ladders can be built for small dams. Hydroelectric has the advantage of long life, and no ongoing environmental damage. It also speeds the rotation of the Earth, resulting in less sleep for me.

But, yes, no form of energy yet found is good for the environment.

"Wind kills birds" WindOWs kill birds. Bird deaths by turbine, 2 per year per turbine. Bird deaths by windows, 100M to 1B. See: Common Eco-Myth: Wind Turbines Kill Birds : TreeHugger

 

Many new big hydro projects are very bad for the environment.

China's Three Gorges Dam: An Environmental Catastrophe?: Scientific American

Hydro can be done in an environmentally sensitive way, but don't expect much new hydro in NA that doesn't cause other damage

 

Sorry if my note seemed to be saying otherwise. Huge new dams have huge ecological implications.

 

It is on my list of future mods

 

How does it speed up the Earth's rotation?

 

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It is, in large measure, a matter of degree. Small scale hydro, especially run of the river, or de-centralized small "stream engines" can be net/net pretty benign. Same with PV solar and solar hot water. Yes there are manufacturing environmental costs, but PV systems can live and produce for decades, amortizing those costs over time makes them quite small compared to other energy. Just for the record, my PV system has been performing at or above spec for nearly 15 years.

Icarus

 

it really all boils down to a lack of throughput on the designers who built these dams. we have this trend of blocking it all... it's a bad trend that is costing us a lot in the end.

it all comes down to the basics. these streams and rivers need to function. the bandaid to all this has been jump pools after the dams. this kinda helps but it doesn't solve the problem that there is an artificial habitat created that has basically nobody watching over them to make sure they can sustain life. the next problem is that man just changed their entire life cycle by making this resting spot that originally were not there. what if that particular animal needed to return down stream but then doesn't?

it's either streams/rivers need to be split upstream and then controlled so the stream/river is only a stream/river it's entire path... or... separate artificial creeks need to be constructed that go the entire length of the dam (around the dam or beside it.... underground?) .... this way, in the end, our creeks and streams stay as they are... or were...

in that case dams would only be stocked fish...

 

Built and operated intelligently, a dam would be little more destructive than a natural reservoir. Built strictly to maximize profit, you get the problems of our dams built decades ago. The issue is not dams, but thoughtless dams.

 

Dams raise water up in the air and thus slow the spin of the Earth, not speed it up. Conservation of angular momentum....

 

Conservation of angular momentum needs to know the water's distance from the spin axis, not its elevation above the geode. Thus, the storage latitude change is far more important than the storage elevation change.

A dam on the equator would clearly slow the earth's rotation. But a dam at higher latitude, impounding water that would have flowed into the ocean, will speed up the rotation if the location is closer to the axis than a momentum-weighted average of the oceans surface, which should be somewhat close to the equator. (Calculating the balance point would be an interesting exercise, which I leave to the reader.)

My memory (augmented by a quick skim on Google) is of consensus that the bulk of impounded water is in the Northern mid latitudes, causing a speed up of rotation. But individual dams will have different results.

 

For a far more extensive report in these two dams, Elwha and Glines Canyon, see the Seattle Times Special Report: Elwha - The grand experiment to tear down two dams and return an Olympic wilderness to its former glory.

 

I hope they are stressful. Its only because the land was protected that this dam removal has a chance to restore the ecosystem.

There are also good hydro electric projects. The one by me LCRA was built during the depression mainly to manage the drought/flood cycles but with bonds paid for by electric and water sales. During the severe drought this year it has helped keep the ecosystem and the people in better shape. LCRA created a series of dams that widened and slowed the river that somehow get names of lakes. When there is flooding more water is let through the dams, but the infrastructure can handle more water flow and higher water levels than if nothing was done. In droughts like this year less water is let through, though enough to feed areas down river. I like hydro when it is done in an environmentally thoughtful way, but not when it is done like three gorges or Elwha.

 

The best energy is conservation and efficiency - building, maintaining and using things that are climate appropriate and sustainable. Then comes small hydro, including hydraulic rams, small geothermal, solar, wind and waves. The worst approach is "go get more," indicating you are not efficiently making use of what you presently have.

Buildings must be properly oriented by latitude, geography, elevation and prevailing wind. Windows must be dual or triple pane. Walls and roofs must provide excellent insulation. Eves must provide latitude-appropriate shading on 21 June (Summer Solstice) and optimum sun on 21 December (Winter Solstice). The energy cost of manufacturing must be considered, i.e., SIPs (structural insulated panels) over sticks-n-boards construction. Landscaping with native vegetation (no irrigation required, no mowing of artificial lawns).

 

Whatever. The change in the Earth's rotational velocity is undetectable to any of the human senses, so .... sleep well, you'll never notice it!

 

Agreed......

 

The carbon in vegetation is newly-sequestered, and is all released back into the atmosphere, thus there is no net carbon footprint from vegetation that decays in a lake.

On the contrary! Fusion releases large quantities of high-energy neutrons which create radioactive isotopes in the containment vessel. In addition, work on contained, controlled fusion (as opposed to explosive, uncontained fusion) has been going on for over half a century, and there has been virtually no progress to date. While it is theoretically possible, it holds very little promise as a potential contributor to our energy needs.

Unlike solar cells and wind turbines, which we can make today, and even fission reactors, which we can make today if we are willing to accept the risks, and leave the waste problem for the next generation to deal with, fusion reactors for energy are at best many many decades away.

Not "promising" at all.