Suppose
that over the next
decade or two the
forecasts of global
warming start to come
true. Color has drained
from New England's
autumns as maple trees
die, and the Baltimore
oriole can no longer be
found south of Buffalo.
The Dust Bowl has
returned to the Great
Plains, and Arctic ice
is melting into open
water. Upheavals in
weather, the environment
and life are
accelerating around the
world.
Then
what?
If
global warming occurs as
predicted, there will be
no easy way to turn the
Earth's thermostat back
down. The best that most
scientists would hope
for would be to slow and
then halt the warming,
and that would require a
top-to-bottom revamping
of the world's energy
systems, shifting from
fossil fuels like coal,
oil and natural gas to
alternatives that in
large part do not yet
exist.
"We
have to face the fact
this is an enormous
challenge," said
Dr. Martin I. Hoffert, a
professor of physics at
New York University.
But
interviews with
scientists, environment
advocates and industry
representatives show
that there is no
consensus in how to meet
that challenge. Some
look to the traditional
renewable energy
sources: solar and wind.
Others believe use of
fossil fuels will
continue, but that the
carbon dioxide can be
captured and then stored
underground. The nuclear
power industry hopes
concern over global
warming may help spur a
revival.
In an
article in the journal
Science last November,
Dr. Hoffert and 17 other
experts looked at
alternatives to fossil
fuels and found all to
have "severe
deficiencies in their
ability to stabilize
global climate."
The
scientists believe that
technological fixes are
possible. Dr. Hoffert
said the country needed
to embark on an energy
research program on the
scale of the Manhattan
Project that built the
atomic bomb during World
War II or the Apollo
program that put men on
the moon.
"Maybe
six or seven of them
operating
simultaneously," he
said. "We should be
prepared to invest
several hundred billion
dollars in the next 10
to 15 years."
But to
even have a hope of
finding a solution, the
effort must begin now,
the scientists said. A
new technology usually
takes several decades to
develop the underlying
science, build pilot
projects and then begin
commercial deployment.
The
authors of the Science
paper expect that a
smorgasbord of energy
sources will be needed,
and they call for
intensive research on
radical ideas like vast
solar arrays orbiting
Earth that can collect
sunlight and beam the
energy down. "Many
concepts will fail, and
staying the course will
require
leadership," they
wrote. "Stabilizing
climate is not
easy."
The
heart of the problem is
carbon dioxide, the main
byproduct from the
burning of fossil fuels.
When the atmosphere is
rich in carbon dioxide,
heat is trapped,
producing a greenhouse
effect. Most scientists
believe the billions of
tons of carbon dioxide
released since the start
of the Industrial
Revolution are in part
to blame for the
one-degree rise in
global temperatures over
the past century. Carbon
dioxide concentrations
are now 30 percent
higher than
preindustrial levels.
With
rising living standards
in developing nations,
emissions of carbon
dioxide are increasing,
and the pace of warming
is expected to speed up,
too. Unchecked, carbon
dioxide would reach
twice preindustrial
levels by midcentury and
perhaps double again by
the end of the century.
That could force
temperatures up by 3 to
10 degrees Fahrenheit by
2100, according to
computer models.
Because
carbon dioxide is
colorless, odorless and
disperses immediately
into the air, few
realize how much spills
out of tailpipes and
smokestacks. An
automobile, for example,
generates perhaps 50 to
100 tons of carbon
dioxide in its lifetime.
The
United States produces
more carbon dioxide than
any other country by
far. Each American, on
average, generates about
45,000 pounds of carbon
dioxide a year. That is
about twice as much as
the average person
living in Japan or
Europe and many times
more than someone living
in a developing country
like Zimbabwe, China or
Panama. (Even if the
United States achieves
President Bush's goal of
an 18 percent reduction
in the intensity of
carbon dioxide emissions
by 2012, the output of
an average American
would still far exceed
that of almost anyone
else in the world.)
Even
if all emissions stop,
levels of carbon dioxide
in the air will remain
high for centuries as
the Earth gradually
absorbs the excess.
Currently,
the world's energy use
per second is about 12
trillion watts — which
would light up 120
billion 100-watt bulbs
— and 85 percent of
that comes from fossil
fuels.
Of the
remaining 15 percent,
nuclear and
hydroelectric power each
supply about 6.5
percent. The renewable
energy sources often
touted as the hope for
the future — wind and
solar — provide less
than 2 percent.
In
March, Dr. Hoffert and
two colleagues reported
in Science that to limit
the temperature increase
to 3.6 degrees
Fahrenheit,
non-carbon-dioxide-emitting
sources would have to
generate 7 trillion to
25 trillion watts by
midcentury, 4 to 14
times as much as current
levels. That is roughly
equivalent to adding a
large emissions-free
power plant every day
for the next 50 years.
And by
the end of the century,
they wrote, at least
three-quarters and maybe
all of the world's
energy would have to be
emission-free.
No
existing technology
appears capable of
filling that void. The
futuristic techology
might be impractically
expensive. Developing a
solar power satellite,
for example, has been
estimated at more than
$200 billion.
Energy
Secretary Spencer
Abraham cited the
Science paper from last
November in a speech at
the American Academy in
Berlin two months ago.
Mr. Abraham said that
merely setting limits
and timetables on carbon
dioxide like those in
the Kyoto Protocol could
not by themselves solve
global warming.
"We
will also need to
develop the
revolutionary
technologies that make
these reductions
happen," Mr.
Abraham said. "That
means creating the kinds
of technologies that do
not simply refine
current energy systems,
but actually transform
the way we produce and
consume energy."
Too
Far Away
Some
long-hoped-for options
will almost certainly
not be ready. Fusion —
producing energy by
combining hydrogen atoms
into helium, the process
that lights up the sun
— has been heralded
for decades as a
potentially limitless
energy source, but
scientists still have
not shown it can be
harnessed practically.
Experimental fusion
reactors do not yet
produce more power than
they take to run.
Increased
energy efficiency —
like better-insulated
buildings, more
efficient
air-conditioners, higher
mileage cars — is not
a solution by itself,
but it could buy more
time to develop cleaner
energy.
The
much-talked-about
hydrogen economy, in
which gasoline-powered
engines are replaced by
fuel cells, is also not
a solution. It merely
shifts the question to
what power source is
used to produce the
hydrogen.
Today,
most hydrogen is made
from natural gas, a
process that produces
carbon dioxide that is
then released into the
air. Hydrogen can also
be produced by splitting
apart water atoms, but
that takes more energy
than the hydrogen will
produce in the fuel
cell. If the electricity
to split the water comes
from the coal-fired
power plant, then a
hydrogen car would not
cut carbon dioxide
emissions.
Exploiting
What's Here
A
fundamental problem
remains: how to produce
electricity without
carbon dioxide.
Hydroelectric
power has reached its
limits in most parts of
the world; there are no
more rivers to dam.
Nuclear
power is a proven
technology to generate
large amounts of
electricity, but before
it could be expanded,
the energy industry
would have to overcome
longstanding public
fears that another
accident, like those at
Three Mile Island or
Chernobyl, will occur.
Solutions also need to
be found for disposing
of radioactive spent
fuel and safeguarding it
from terrorists.
Marvin
Fertel, senior vice
president of the Nuclear
Energy Institute, an
industry group, said
warming had become such
a worry that some
environmental groups
were becoming amenable
to new nuclear plants.
"In private, that's
what we get from
them," he said.
Researchers
at the Electric Power
Research Institute in
Palo Alto, Calif.,
espouse a major
expansion of nuclear
power, coupled with a
switch from gasoline to
hydrogen to power cars
and trucks. Electricity
from the nuclear plants
would split water to
produce hydrogen, and
then cables made of
superconductors would
distribute both
electricty and hydrogen,
which would double as
coolant for the cables,
across the country.
"I
think in 30 to 50 years
there will be systems
like this," said
Dr. Chauncey Starr, the
institute's founder and
emeritus president.
"I think the
advantages of this are
sufficient to justify
it."
In the
short run, fossil fuels
will still be widely
used, but it is still
possible to control
carbon dioxide.
In his
Berlin speech, Mr.
Abraham highlighted two
projects the Energy
Department was working
on: carbon sequestration
— the capturing of
carbon dioxide before it
is emitted and storing
it underground — and
FutureGen, a $1 billion
prototype coal power
plant that will produce
few emissions. The plant
will seek to demonstrate
by 2020 how to convert
coal to hydrogen on a
commercial scale that
will then be used to
generate electricity in
fuel cells or turbines.
The waste carbon dioxide
would be captured and
stored.
The
technology for injecting
carbon dioxide is
straightforward, but
scientists need better
knowledge on suitable
locations and leak
prevention.
Sequestration,
however, will probably
not be cost-effective
for current power
plants. The filters for
capturing carbon dioxide
from the exhaust gas
will by themselves
consume 20 percent to 30
percent of the power
plant's electricity.
Renewing
Renewables
Solar
is still a future
promise. The cost of
energy from solar cells
has dropped sharply in
the past few decades.
One kilowatt-hour of
electricity — the
energy to light a
100-watt bulb for 10
hours — used to cost
several dollars when
produced by solar cells.
Now it is only about 35
cents. With fossil
fuels, a kilowatt-hour
costs just a few cents.
But
solar still has much
room for improvement.
Commercial cells are
only 10 to 15 percent
efficient. With much
more research, new
strategies to absorb
sunlight more
efficiently could lead
to cells that reached 50
to 60 percent
efficiency. If the cells
could be made cheaply
enough, they could
produce electricity for
only 1 or 2 cents a
kilowatt-hour.
Dr.
Arthur Nozik, a senior
research fellow at the
National Renewable
Energy Laboratory in
Golden, Colo., said the
advanced solar concepts
were scientifically
feasible. But, echoing
Dr. Hoffert, Dr. Nozik
said: "We need like
a Manhattan Project or
an Apollo program to put
a lot more resources
into solving the
problem. It's going to
require a revolution,
not an evolution. I
wouldn't expect to get
there in 2050 if we're
going at the same
pace."
But if
scientists succeed with
a cheap, efficient solar
cell, "you'd be on
Easy Street," Dr.
Nozik said.
Wind
power is already
practical in many places
like Denmark, where 17
percent of the
electricity comes from
wind turbines. The
newest turbines, with
propellers as wide in
diameter as a football
field, produce energy at
a cost of 4 or 5 cents a
kilowatt-hour. Further
refinements like lighter
rotors could drop the
price by another cent or
two, making it directly
competitive with natural
gas.
Dr.
Robert W. Thresher,
director of the National
Wind Technology Center
at the energy
laboratory, envisions
large farms of wind
turbines being built
offshore. "They
would be out of
sight," he said.
"There's no
shortage of space and
wind."
Solar
and wind power will be
hampered because the sun
doesn't always shine and
the wind doesn't always
blow. The current power
grid is not well suited
for intermittent power
sources because the
amount of power produced
at any moment must match
the amount being
consumed. To exploit the
sun and wind, utilities
would have to develop
devices that could act
as giant batteries.
One
concept is to pump
compressed air into an
underground cavern. When
electricity was needed,
the air would be
released, and the air
pressure would turn a
turbine to generate
electricity.
The
Big Ideas
Then
there are the big ideas
that could change
everything. To get
around the problem of
the intermittency in
solar power, solar
arrays could be placed
where the sun shines 24
hours a day — in
space. The power could
be beamed to the ground
via microwaves.
Another
big idea comes from Dr.
Klaus S. Lackner, a
professor of geophysics
at Columbia University:
what if carbon dioxide
could be scrubbed out of
the air? His
back-of-the-envelope
calculations indicate it
may be feasible,
although he is far from
being ready to
demonstrate how.
But if
that were possible, that
would eliminate the need
to shift from gasoline
to hydrogen for cars.
That would save the time
and cost of building
pipelines for shipping
hydrogen, and gasoline
is in many ways a
superior fuel than
hydrogen. (Hydrogen
needs to be stored under
very high pressure or at
very cold temperatures.)
Owners of gas-guzzling
S.U.V.'s could assuage
their guilt by paying
for the scrubbing of
carbon dioxide produced
by their vehicles.
Eventually,
the captured carbon
dioxide could be
processed to create an
artificial gasoline, Dr.
Lackner said. Then the
world would discover,
much to its surprise,
that everything old
would be new and clean
again.
"Carbon
may actually be just as
clean, just as
renewable," Dr.
Lackner said.