1. Hydropower Ben Warren James Kulinski Dan Lawlor

11. PE = mgh P = energy/time P = mgh/t = m/t * g * h P = ø * g * h Ø = flow rate in kg/sec

12. Ø = 1 kg/s g = 9.8 m/s 2 h = 90 m P=1kg/s * 9.8m/s 2 * 90m = 882 J/s = 882 W

13. The Water Wheel

14. Efficiency ~ 60% 882 W *.60 = 529.2 W This is only converted into mechanical energy!

18. Efficiency ~ 80 % 882 W *.80 = 705.6 W

19. Efficiency ~ 80 % 882 W *.80 = 705.6 W Almost 50% more efficient than water wheels

22. Environmental Impact of Dams

23. Fragmentation of Ecosystems A hydroelectric dam disrupts the natural flow of water. Flooding upstream of the dam can submerge large areas of the landscape, displacing land- dwelling species. Decreased flow downstream of the dam can dry out river banks and tributaries, displacing aquatic species. Dams can interrupt the migratory routes of fish. Salmon have been most notably affected – the adults are often unable to travel upstream, and the young are often caught in the turbines traveling downstream.

24. The larger the dam, the greater the threat to animal populations. Thus, large dams must be constructed with greater caution than smaller 'micro-hydroelectric' dams, which impact the environment much less.

25. To mitigate the impact to fish migration, systems like the 'fish ladder' pictured below have become much more common.

26. A more subtle threat is posed by the 'scouring' of riverbanks downstream from the dam. Dams tend to filter the sediment out of the water, which besides posing a threat to the dam's integrity, also creates a flow of dissolute water that sucks sediment from the banks downstream. Dams will periodically need to purge, resulting in small controlled floods, which also take sediment from the river downstream. Depending upon the composition of the river, this can be more or less of a problem. Rivers with delicate systems of sandbars can erode and widen at a very destructive rate.

27. An eroded riverbank in the Hinboun river in Laos, downstream from the “Nam Theun 2” dam.

28. Human Impact The geographical changes resulting from large dams can have complicated political effects. The 'Three Gorges' Dam on China's Yangtze River is the world's largest electrical generation plant of any kind. It is 185 metres tall, and 2,335 metres long. It generates 80 Terawatt-hours of electricity a year! The Three Gorges Dam brought water levels up by as many as 100 meters in its flood basin, and has displaced as many as 1,300 archeological and historical sites. Many of these are some of the oldest and most academically rich in the world. The Three Gorges also displaced a large portion of the local population. However, since the dam provided them with cheap energy, reactions have been mixed.

31. Other Human Impacts The construction of a single dam upstream can have drastic effects on an entire river. These effects can cross over political boundaries. Egypt's Aswan Dam has lowered the level of the Nile in several of the countries downstream.

33. References http://en.wikipedia.org/wiki/Hydroelectric_dams#Environmental_damage http://www.google.com/imgres?imgurl=http://static.howstuffworks.com/gif/fish- ladder-2.jpg&imgrefurl=http://adventure.howstuffworks.com/outdoor- activities/fishing/fish-conservation/fish-populations/fish- ladder1.htm&h=300&w=400&sz=29&tbnid=OYerdHbfRp6jsM:&tbnh=93&tbn w=124&prev=/images%3Fq%3Dfish%2Bladder&hl=en&usg=__dsSKweicRL MkO3DAGccsp_tMz9A=&ei=7IWCS4_AG9aOtgev4fHXBg&sa=X&oi=image_ result&resnum=6&ct=image&ved=0CBMQ9QEwBQ http://www.internationalrivers.org/en/southeast-asia/laos/theun-hinboun http://en.wikipedia.org/wiki/Three_Gorges_Dam http://www.emt-india.net/process/power_plants/img/hydro2.gif http://www.usbr.gov/power/edu/pamphlet.pdf www.wikipedia.org