heat in the winter and repel it during
) & " - * / ( 0 ' 5 ) & # 0 % : J T ) & " - * / ( 0 ' 5 ) & ) & " 3 5
the summer.
TIDaL PowER
* G Z P V B S F F Y Q F S J F O D J O H B O J M M O F T T
Underwater turbines have proved able
: P V S M J G F G P S D F I B T C F F O
to efficiently harness the immense
energy contained in waves and tides.
P Q Q S F T T F E B O E E J T F N Q P X F S F E
Experimental units have been tested
: P V S I F B S U I B T T I V U E P X O
in the United States, UK and other
locations around the world. A major
obstacle to developing reliable tidal
* B N B O> F Y P S D J T U N F E J D B M J O U V J U J W F
power is operating in such a turbulent,
* X J M M D B T U P V U C F M J F G T B O E E F D F Q U J P O T U I B U I B W F
B U U B D L F E Z P V S M J G F G P S D F ‡ S J H I U P V U P G Z P V S I F B S U
changeable and fragile environment.
: P V S I F B S U X J M M P Q F O J N N F E J B U F M Z
Currently, tidal resources for creating
* X J M M i T F F u B O E S F E J S F D U Z P V U P Z P V S T Q J S J U T
utility-level electricity are concentrated
Q V S Q P T F B O E Z P V S i U S V F u M J G F O P X
in a few places, such as Alaska.
wIND
X X X F O G P S D J O H I J T H S B D F D P N r 3 F W + V M J B O B 5 B Z M P S
1 I % r
Whether on- or offshore, today’s high-
efficiency wind towers capture steady
breezes to turn a turbine and generate
electricity. This ancient, zero-emission
energy source is heating up in Europe,
Asia and the United States. Texas and
New York are leading wind states, but
44 others are said to have useful re-
sources. North Dakota alone could sup-
ply a third of the country’s electricity,
according to the American Wind Energy
Association. The opposition to wind is
mostly aesthetic. Negative effects on
migratory bird populations is another
concern. Opposition has been powerful
enough to stall major initiatives, such
as the offshore Cape Wind Project in
Massachusetts.
All in all, “State leaders have
begun to move us in the right direction
on energy, but we must do a lot more at
every level of government,” urges Dave
Hamilton, director of the Sierra Club’s
global warming program. “Congress
can flip the switch on America’s clean
energy future by increasing fuel econ-
omy standards to at least 35 mpg
and requiring that we get 15
percent of our electricity
from clean, homegrown
sources like wind, solar,
and biomass by the
year 2020.”
October 2008 41
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