lecture 10 alternative energy

lecture 10 alternative energy - 2/17/09
 GEOL 103 Spring...

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Unformatted text preview: 2/17/09
 GEOL 103 Spring 2009 Environment
of
the
Earth
 Lecture 10: Alternative energy resources Reading: Montgomery Chapter 15 Oil
 Very
limited
in
supply;
current
reserves
give
about
40
year
supply
 at
current
consump9on
rates
 Most
large
oil
fields
are
now
exhausted
 United
States
relies
on
foreign
imported
oil
 Most
oil
is
used
in
the
transporta9on
sector,
plas9cs
industry
 Coal
 Natural
gas
 Huge
reserves
in
United
States,
enough
for
300‐400
years
 Found
in
nearly
all
petroleum
reservoirs
 But…..
 Declining
reserves,
supply
will
last
on
the
order
of
decades
 Large
reserves
are
primarily
BITUMINOUS
GRADE
COAL
with
HIGH
 VOLATILE
CONTENT
(e.g.,
sulfur)
 Most
natural
gas
is
imported
 Coal
is
dirty,
from
mining
to
electricity
produc9on
 Possible
recovery
of
huge
natural
gas
resource
in
methane
hydrates
 in
the
future
 
Mining
ac9vi9es
(mine
collapse,
acid
water
discharge)
 
Coal
combus9on
(ash,
soot,
carbon
dioxide,
sulfur

acid
rain)
 
Most
electricity
in
US
is
generated
in
coal
fired
power
plants
 1
 2/17/09
 Global
energy
produc6on,
by
source
in
2004
 Terms:
 Kine6c
energy:
Energy
associated
with
an
objects
mo6on
 Fossil
fuels
account
for
more
than
85%
 Carbon
dioxide
and
greenhouse
warming
 Poten6al
energy:
Energy
associated
with
an
objects
posi6on
 The
remaining
15%
uses
other
energy
 sources:
 
Nuclear
energy
 
Energy
contained
in
moving
fluids
 
 
wind
 
 
water
 
Geothermal
energy
 These
ALTERNATIVE
ENERGY
SOURCES
will
 become
increasingly
important
as
the
current
 energy
and
environmental
crisis
deepens
 Nuclear
energy:
harnessing
energy
contained
in
atomic
nuclei
 Uranium
235
–
the
fissionable
nucleus
 Fissionable:
a
nucleus
that
can
be
made
unstable
by
addi6on
of
a
 neutron
 • Fission:
SpliXng
large
atomic
nuclei
into
smaller
atoms

 • (this
is
what
happens
in
nuclear
reactors)
 Adding
a
neutron
to
uranium
235
creates
uranium
236,
which
is
an
 unstable
nucleus

 • Fusion:
Combining
small
atomic
nuclei
into
larger
atoms
 • (this
is
what
happens
in
stars)
 Fission
of
uranium
235
generates
fission
fragments
and
high
energy
 neutrons
 
 
barium
143
and
krypton
91
 
 
two
high
energy
neutrons
 Today’s
nuclear
energy
industry
relies
on
geologic
deposits
of
 uranium
to
produce
energy
in
nuclear
reactors
 2
 2/17/09
 Chain
reac9on
 Natural
uranium
deposits
 • Mostly
composed
of
uranium
238
(99.3%)
 • Small
amounts
of
uranium
235
are
processed
from
natural
 uranium
deposits
and
concentrated
into
fuel
rods
 • Closely
spaced
uranium
235
increases
the
chance
that
a
high
 energy
neutron
will
enter
another
uranium
235
nucleus
 • Chain
reac9on
occurs
under
these
condi9ons
 Conven6onal
nuclear
fission
reactor
 Problems
with
Nuclear
Power
are
related
to
radioac6ve
waste
 Geology
of
Uranium
 •  95%
of
uranium
found
in
sedimentary
(or
 metasedimentary)
rocks
 –  Generally
found
in
sandstones
 –  Uranium
is
weathered
from
other
rocks
and
 deposited
by
migra6ng
ground
water
 –  Minor
amounts
of
uranium
are
present
in
many
 crustal
rocks
 –  Grani6c
rocks
and
carbonates
may
be
rich
in
 uranium
 –  Uranium
oxide
(U3O8):
“yellowcake”
  Fission
products
are
unstable
nuclei,
will
undergo
 spontaneous
disintegra6ons
 • High
energy
par6cles
 • Containment
of
waste
is
possible
 • Chance
of
waste
to
enter
groundwater
is
high
 • Currently,
high
level
wastes
are
stored
at
nuclear
power
plants
 3
 2/17/09
 Level
of
radia6on
in
homes
from
radon

 U.S.
nuclear
power
plants
 1
Curie
–
3.7
x
1010
nuclear
disintegra6ons
per
second,

 4
 2/17/09
 Nuclear
Power
‐
Fusion
 •  •  •  •  •  •  •  •  Nuclear
fusion
is
the
opposite
of
nuclear
fission
 Sun
is
a
gigan6c
fusion
reactor
 Fusion
is
a
cleaner
form
nuclear
power
than
fission
 Fusion
–
involves
combining
smaller
nuclei
to
form
larger
 ones
 Can
produces
abundant
energy
 Hydrogen
is
plen6ful
and
is
the
raw
material
required
 Fusion
difficult
to
achieve
given
current
technology

 Theore6cal
–
not
yet
economically
aiained
 •  Fusion
of
1g
of
hydrogen
produces
as
much
energy
as
 burning
23,000
kg
of
coal!
 Solar
Energy
 •  Abundant
solar
energy
reaches
the
earths
surface
 –  Be
dissipated
in
various
ways
 –  Solar
energy
is
free,
clean,
and
a
renewable
resource
 –  Limita6ons
are
la6tude
and
climate
 •  Solar
Hea6ng
 –  Passive
solar
hea6ng:
no
mechanical
assistance
 •  Warming
tanks
of
water,
heat
released
during
the
night
 –  Ac6ve
solar
hea6ng:
mechanical
circula6on
of
solar‐heated
 water
 •  Solar
Electricity
 –  Photovoltaic
cells
 Distribu6on
of
solar
energy
 5
 2/17/09
 Home
and
building
design
improvements
 Passive
solar
hea6ng
drama6cally
reduces
hea6ng
 (and
cooling)
costs
 Most
of
the
energy
savings
in
this
country
could
be
 realized
by
energy
efficient
residen6al/office
building
 design
 Photovoltaic
cells:
 The
photoelectric
effect:

When
light
strikes
certain
metals,
electrons
 are
released
 Direct
genera9on
of
electricity
by
the
interac9on
of
solar
energy
with
 thin
sheets
of
metal
 Free
electrons
flow
along
a
chemical
gradient
between
two
different
 types
of
metal
–
crea9ng
an
electrical
charge
 S9ll
very
expensive
and
inefficient
–
a
very
small
amount
of
solar
 energy
is
actually
used
in
electrical
energy
produc9on
 Can
meet
energy
needs
in
remote
areas
for
specific
purposes
 Geothermal
Power
 •  The
earth
contains
a
great
deal
of
heat,
most
 of
it
leo
over
from
its
early
history,
some
 generated
by
decay
of
radioac6ve
elements
in
 the
earth
 •  Interior
of
the
earth
is
very
hot
 –  Abundant
source
of
heat
and
hot
water
 •  Magma
rising
into
the
crust
bring
abundant
 heat
up
into
the
crust
as
geothermal
energy
 •  Heat
escaping
from
the
magma
heats
water
 and
the
water
convec6vely
circulates
 6
 2/17/09
 Geothermal
Power
 •  Applica6ons
of
Geothermal
Energy
 –  Power
plants
(limited
to
high
geothermal
gradient
areas)
 •  Power
plants
in
western
US
(California,
Nevada),
Iceland,
Japan
 –  Circula6on
of
geothermal
water
(and
heated
air)
through
 homes
to
raise
temperature
prior
to
hea6ng
in
a
boiler
 •  Domes6c
cold
water
may
be
40
deg
C
in
the
winter,
geothermal
 sources
can
raise
temperature
to
50‐70
degrees
before
water
 enters
a
domes6chot
water
heater
 Energy
in
falling
water:
Poten6al
energy
of
water
 Hydropower:
Energy
derived
from
falling
water
 Moving
water:
early
applica6ons
 • Water
wheels
used
to
grind
wheat
into
flour,
powder
mills
(gun
powder)
 • Flowing
water
used
to
power
tools
in
17th
‐18th
farms
 • Transfer
of
energy
from
flowing
water
to
gear
shaos
that
drills,
etc.
were
hooked
up
 to
 • The
hydrologic
cycle:
evaporates
water
from
the
oceans,
rain
on
land,
water
flows
down
 hill
back
to
the
ocean
 • Modern
hydropower
interrupts
this
cycle
 Glen
Canyon,
upstream
from
 The
Grand
Canyon
 Photo
from
the
1940’s
 7
 2/17/09
 Difference
in
height
between
Lake
Powell
and
Colorado
River
is
178
meters
 The
weight
of
water
falling
through
178
meters
creates
an
enormous
amount
of
kine6c
energy
 Wind
Energy
 •  The
winds
are
ul6mately
powered
by
the
sun,
and
 thus
wind
energy
can
be
viewed
as
a
variant
of
solar
 energy
 •  Clean
and
renewable
energy
resource
 •  Many
technological
improvements
have
increased
 the
energy
produc6on
from
windmills
 •  Areas
of
best
wind
genera6on
poten6al
tend
to
be
 far
from
popula6on
centers
that
would
benefit
from
 them
 •  Abundant
small
scale
windmills
involve
small
wind
 turbines
lioing
water
on
a
ranch
or
farm
 Silta6on
and
low
water
levels,
reduce
life6me
of
dam
and
lowers
energy
produc6on
 8
 2/17/09
 Palm
Springs,
California
 9
 ...
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