BESC 320 – Water and Bioenvironmental Science
(Week 8; 13-17 Mar 2017)
Hydropower
19% of Global electricity is from hydropower!
(Atlas of Water, Vignette 21: Water for Energy)
Only 10% in US, accounting for 73% of renewable energy (http://powerscorecard.org)
History
Historic uses of waterpower were to elevate water into aquaducts (norias), and entering the industrial revolution to turn millstones or sawblades, for production of milled grains and lumber. Use of hydropower to make electricity goes back to the 1880s, but became huge with the Hoover Dam in 1931.
Global perspective—Installed megawatts:
WRI
Percent of power through hydro (see vignette 21 in your Atlas of Water):
Note major patterns—near mountain ranges, major rivers, others?
So water infrastructure is vast. Find a lake or river—stop it up—spin turbines with released water. How easy is it to find a lake in Texas? Interestingly, there are no natural lakes in Texas, except arguably Lake Caddo.
Here is a look at how dams work…
Here is a worthy video on dam mechanics: http://www.youtube.com/watch?v=Hu60nn-GFzQ (43s)
The fundamental physics are:
Q α Ah, where A=catchment area, h=head, Q=outflow. See example:
Demo.
Advantages of dams:
· Tremendous power output
· Arguably, flood control
· Provide water reserves
· Provide recreation opportunities
Problems with dams:
· Interfere with nature
o migratory species, upstream colonizations
o habitat loss of the inundation zone
o alters temperature regime
§ potential amelioration by hypolimnetic release
o altered flow dynamics (many species have particular requirements)
§ operators release water according to electricity needs
o alters sediment structure
o alters floodplain dynamics
· Interferes with people
o displaces indigenous peoples
o displaces landowners
· sedimentation
· increased evaporative loss
Case study: Three Gorges Dam
The Three Gorges Dam in China is the largest dam in the world. Proposed in 1919, it has a long history. It was completed in 2003ish. It harnesses the power of the Yangze River and produces the energy of 18 nuclear power plants. However, the 395 square mile reservoir displaced 1.3 million people and changed forever the waterway’s ecosystem. The reservoir obliterates many sites of cultural and archaelogical interest. Reservoirs created by dams also increase evaporation, resulting in a loss of fresh, usable water. The weight of impounded water is being blamed for settling in the broader landscape, involving many unusual occurrences of landslides, etc.
Basic Statistics of the Three Gorges Dam Project
Dam Height: 185 ms (head of 175 m)
Dam Length: 2.335 km
Installed Power Generation Capacity: 22,500 MW (84.7 billion kWh) annually
Project Investment: $ 24.65 billion (reported)
1994.12.14 Official commencement of the Three Gorges Dam project
2003.06.16 Permanent ship lock opened to navigation
2003.07.10 Power generating began with Generator No. 2
2006.05.20 Completion of concreting to the entire dam to 185m level
2010.10.26 Water level reached 175m for the first time
http://en.wikipedia.org/wiki/File:Yangtze_longitudinal_profile_upstream.JPG
Lest I fail to mention, the dam is built in a seismically active area.
Visualize…
Water and human populations
Mini Case Study—snail genetics across flow control device
· Rob Dillon, College of Charleston, SC
· Assessed genetic diversity of snails in a river previous to road construction.
Road construction involved a concrete culvert.
· Re-assessed genetics a few years later and found marked structure above and below the culvert; essentially two different populations.
· Unusual occurrence of a storm washing out the culvert.
· Reassessment of genetics showed homogenization.
Inventions questions?
Note that major scale Hydro may remain de rigeur but small scale hydro may be an important part of energy security going into the future at all economic scales (developed and developing countries): e.g. …
http://www.internationalrivers.org/resources/tide-turns-on-unconventional-hydropower-1893