WELCOME TO PERIOD 24: WATER ENERGY. Homework #23 is due today.

Transcription

1 WELCOME TO PERIOD 24: WATER ENERGY Homework #23 is due today.

2 PHYSICS 1104 PERIOD 24 What is the Earth s water cycle? How is water used to generate electricity? What effects will climate change have on the fresh water supply?

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4 The Earth s water cycle Water from oceans, lakes, rivers, and the soil evaporates when radiation from Sun warms the Earth s surface. Water vapor rises, is cooled, and condenses on dust particles, forming clouds. When clouds become saturated, precipitation falls as rain or snow. Precipitation eventually runs back into lakes and oceans and the cycle repeats. Latent heat of vaporization is removed from the atmosphere when water evaporates and is added when water vapor condenses. Solar energy drives the water cycle.

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6 Example: you roll the cloud cube and are directed to a lake. Source:

7 Water contamination points: for each move you made on the diagram, add or subtract contamination points. Move from: To: Points Explanation of points Clouds all +1 Airborne contaminants are absorbed Animal Soil +2 Wastes Animal Clouds remove all Water is purified as it is respired Soil Plants -1 Some plants absorb pollutants Soil River +2 Runoff carries pollutants into river Soil Groundwater -1 Soil filters some pollutants Soil Clouds remove all Water is purified as it evaporates Plants Animals +1 Contaminants are ingested Plants Clouds remove all Water is purified as it is transpired Ocean Clouds remove all Water is purified as it evaporates Lake Clouds remove all Water is purified as it evaporates Lake Groundwater -1 Soil filters some pollutants Lake Animals +1 Contaminants are ingested Lake River +1 Water moves downstream Glacier Groundwater -1 Soil filters some pollutants Glacier River +1 Water moves downstream Glacier Clouds remove all water is purified as it evaporates Groundwater Lake or river -1 Soil filters some pollutants River Groundwater -1 Soil filters some pollutants River Lake or ocean +1 Water moves downstream River Clouds remove all Water is purified as it evaporates River Animals +1 Contaminants are ingested

8 Causes of ocean tides The moon s gravitational force causes the oceans to form two bulges, one on each side of the Earth. As the Earth spins on its axis, land bordering the oceans passes through both bulges each day. This produces two high tides and two low tides per day. The gravitational attraction between the Earth and the moon causes the water on the side facing the moon to be pulled toward the moon. On the opposite side of the Earth, water tries to continue moving away from the Earth, forming a bulge. Tide_overview.svg

9 Tidal generators

10 Ocean and river turbines Instead of damming a harbor, underwater turbines can use river and ocean currents or ocean waves to generate electricity. This reduces the environmental consequences of damming a harbor. The SeaGen tidal energy system in Northern Ireland's Strangford Lough is the world s largest tidal current generator.

11 Shallow geothermal wells provide water at 55 o F to heat and cool buildings

12 Electricity from geothermal energy Heat in the Earth s core is the result of radioactive decay of unstable isotopes. Thermal energy released from these fission reactions raises the temperature of the Earth s core to 9,000 O F (5,000 O C). Thermal energy is conducted from the core through the Earth s mantle. Hot water and steam can be vented in hot springs, such as the Old Faithful Geyser in Yellowstone National Park in Wyoming. This thermal energy can produce the steam needed to turn generator turbines This type of geothermal energy is available only in geologically unstable areas, such as volcanically active Iceland. _Faithfull-pdPhoto.jpg

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14 Retreat of Whitechuck Glacier Whitechuck Glacier in Glacier Peak Wilderness in Whitechuck glacier in Its edge has retreated 1.2 miles.

15 A rain shadow produces an arid region Source:

16 Retreat of mountain glaciers Mountain glaciers will disappear in this century, many before Billions of people depend on glacial melt water for drinking, irrigation, and hydroelectric power. Many glacial lakes are impounded by earthen dams. As melt water increases lake volume, these dams could fail, flooding valleys downstream.

17 Consequences of decreased melt water Much irrigation water comes from lakes that are replenished by glacial melt water. This is particularly true in South America. Glacial melt water is the primary source of the river water used to generate hydropower, especially in the South America Andes Mountains, the European Alps, and the mountain ranges of the Pacific Northwest. Other energy sources will be needed to replace this hydropower.

18 Consequences for fresh water supply After mountain glaciers disappear, one to two billion people will be affected by less fresh water. Possible solutions? Pipe water in from other locations Desalinize sea water Purify and recycle used gray water All of the options cost money and require energy!

19 BEFORE THE NEXT CLASS Read textbook chapter 25. Complete Homework Exercise 24. Print out Activity Sheet 25