Download WELCOME TO PHYSICS 1103

WELCOME TO PERIOD 24:
WATER ENERGY
Homework #23 is due today.
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?
Source: http://pmm.nasa.gov/education/sites/default/files/article_images/Water-Cycle-Art2A.png&imgref
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.
Source: http://www.education.noaa.gov/Freshwater/Water_Cycle.html
Example: you roll the
cloud cube and are
directed to a lake.
Source: http://www.education.noaa.gov/Freshwater/Water_Cycle.html
Water contamination points: for each move you made
on the diagram, add or subtract contamination points.
Move from:
Clouds
Animal
Animal
Soil
Soil
Soil
Soil
Plants
Plants
Ocean
Lake
Lake
Lake
Lake
Glacier
Glacier
Glacier
Groundwater
River
River
River
River
To:
all
Soil
Clouds
Plants
River
Groundwater
Clouds
Animals
Clouds
Clouds
Clouds
Groundwater
Animals
River
Groundwater
River
Clouds
Lake or river
Groundwater
Lake or ocean
Clouds
Animals
Points
+1
+2
remove all
-1
+2
-1
remove all
+1
remove all
remove all
remove all
-1
+1
+1
-1
+1
remove all
-1
-1
+1
remove all
+1
Explanation of points
Airborne contaminants are absorbed
Wastes
Water is purified as it is respired
Some plants absorb pollutants
Runoff carries pollutants into river
Soil filters some pollutants
Water is purified as it evaporates
Contaminants are ingested
Water is purified as it is transpired
Water is purified as it evaporates
Water is purified as it evaporates
Soil filters some pollutants
Contaminants are ingested
Water moves downstream
Soil filters some pollutants
Water moves downstream
water is purified as it evaporates
Soil filters some pollutants
Soil filters some pollutants
Water moves downstream
Water is purified as it evaporates
Contaminants are ingested
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.
http://en.wikipedia.org/wiki/File:
Tide_overview.svg
Tidal generators
http://www.alternative-energy-news.info/technology/hydro/tidal-power/
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.
http://www.alternative-energynews.info/technology/hydro/tidal-power/
Shallow geothermal wells provide water at
55 oF to heat and cool buildings
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 OF (5,000 OC).
• 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.
http://en.wikipedia.org/wiki/File:Old
_Faithfull-pdPhoto.jpg
http://en.wikipedia.org/wiki/File:Glacier_Mass_Balance_Map.png
Retreat of Whitechuck Glacier
Whitechuck Glacier in Glacier Peak Wilderness in 1973.
Whitechuck glacier in 2006. Its edge has retreated 1.2 miles.
http://en.wikipedia.org/wiki/File:Whitechuck_glacier_2006.jpg
A rain shadow produces an arid region
Source: http://upload.wikimedia.org/wikipedia/commons/thumb/9/9a/Rainshadow_copy.jpg
Retreat of mountain glaciers
Mountain glaciers will disappear in this century, many
before 2050.
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.
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.
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!
BEFORE THE NEXT CLASS…
Read textbook chapter 25.
Complete Homework Exercise 24.
Print out Activity Sheet 25