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A common misconception is that hydroelectricity has the advantage over other renewables of requiring less land. This is not the case. The surface area of Lake M
by scythe 12y ago
A common misconception is that hydroelectricity has the advantage over other renewables of requiring less land. This is not the case. The surface area of Lake Mead is 640 square kilometers -- this much ecologically viable land was destroyed to make way for hydroelectricity. The power generation capacity afforded by the Hoover Dam on this lake is roughly 2 GW.
A solar panel produces roughly (we're lowballing) 100 watts per square meter. Solar panels to produce 2 GW -- the power output of Lake Mead -- would cover about 20 million square meters, or 20 square kilometers. If we assume the solar panels only operate at capacity for a third of a day, that's 60 square kilometers. If we also assume that only half of the used land is actually light-capturing, that's 120 square kilometers.
Even under the most pessimistic of assumptions, solar still uses five times less land than hydro. Realistic solar installations would probably be significantly more efficient than I've assumed. Batteries are also significantly more space-efficient than hydroelectric storage.
- hdevalence 12y agoInteresting. I suppose it makes sense, in a way: solar power captures solar energy directly, whereas hydro captures solar energy only indirectly, through the water cycle. Do you have any ballpark ideas about how the cost of producing the dam (most concrete, I guess) compares to the cost of producing 120 km^2 of solar panels + 'enough' battery capacity, in terms of some kind of ecological footprint? My intuition is that the ecological capital costs of solar panels greatly exceed the capital costs of the dam, but I have little faith in my intuition....
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- snowwindwaves 12y agoBallpark cost of developing small high head hydro plants with a weir (no dam) is 3-5 million dollars per MW. But these usually flood a minimal area like 10000 square meters. Public companies that develop hydro power projects annual reports is a good place to look for this type of information.
- jqm 12y agoYes, but Lake Mead serves an additional valuable function as a water storage facility. I'm guessing that is it's primary value. The power generation is secondary.
- cwal37 12y agoIt's also a misconception to equate huge-reservoir hydro with all hydro. The Norwegians have incredibly high head, phenomenally efficient hydro in the mountains with minimal environmental impact. We have run of river hydroelectric in the states that diverts some water via penstock, as well as canal-based systems and those that utilize Army Corp dams. In fact, there is significant non-powered dam resource available: http://nhaap.ornl.gov/content/non-powered-dam-potential http://nhaap.ornl.gov/content/non-powered-dam-potential I'm actually working on national-level hydro assessments at a national lab. We don't really predict more huge reservoir installments, but there is plenty of capacity out there. These set-ups (particularly non-powered dams) are also generally pretty cheap per kWh generated over their lifetimes (which in some cases reaches 70+ years).
- EdwardDiego 12y ago> We have run of river hydroelectric in the states that diverts some water via penstock Do you have wildlife issues to consider in the design? E.g., are the dams on rivers fish migrate up?
- cwal37 12y agoWell, run-of-river installations actually don't have dams, and you can prevent most fish with just some mesh, so you're avoiding that impact entirely.
- EdwardDiego 12y agoAh cool, that's good to hear (so long as flows are sustainable, unlike some of our proposals for 'harnessing all that wasted water')
- sbierwagen 12y agoWhy only 70 years? Does the dam actually crumble to pieces, or is 70 years how long it takes for maintenance costs to equal construction costs?
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- walshemj 12y agoYou can turn hydro on and off quickly and it works during the night
- VLM 12y agoAlso, traditionally you install solar panels on steel pillars set in concrete in the ground, but theres no electrical reason you can't mount them on top of the hydro lake, on floats. There are engineering concerns with waves and the usual problems anytime you mix water electricity and metal. There are biological concerns where polluted water is already anoxic enough so blocking light is not going to help. Still there's no inherent reason the land can only be applied to one tech. Maybe if you have an infinite supply of cheap incredibly tall concrete pylons you could mount windmills too, although that's sounding unlikely.
- mrfusion 12y agoSo it makes me wonder, could we place floating solar panels on lake Meade?
- dlisboa 12y ago> A common misconception is that hydroelectricity has the advantage over other renewables of requiring less land. Is this really a common misconception? Has no one ever seen a dam? I can't think of any other form of energy production whose sole requirement is massive amounts of land to flood. Brazil's debate on hydroelectric dams (and we have a lot of them) are solely bound on the flood areas and environment/habitat destruction they cause. I really doubt that's a common misconception.
- pekk 12y agoHydro was not the purpose of making Hoover Dam, so the rest of your argument fails.
- daemin 12y agoBeing just a tourist to Hoover Dam it was explained to me that the main purpose of the dam was to regulate the water and have it available for people and farmers. Power generation was only ever a secondary consideration.