CHAPTER
4 - Gleanings from SCIENCE, Aug 13, 2004
No sooner was I back at my office
at the University of Wisconsin than I read the front cover of
SCIENCE magazine, published
weekly
by the American Association for the Advancement of Science. It
was a special issue, mostly devoted to “Toward a Hydrogen Economy”.
It turned out to be the second part of a “1-2 punch” that
sent me spinning into a whole new orbit of thought.
The editors of that special issue,
Robert Coontz and Brooks Hanson, wrote a very clear introduction,
entitled “Not So Simple”,
in which they pointed out that, while hydrogen atoms are common
on earth, they are eager to bond, so they are very rare in unattached
form. Releasing them requires breaking chemical bonds, and that
requires energy. Once released, the atoms pair up into two-atom
molecules, becoming a light, invisible gas that is hard to store,
transport, liquefy or handle safely. Don Kennedy, the Editor-in
Chief for SCIENCE, went on to explain that glib announcements of
the Hydrogen Fuel Initiative and FreedomCAR Part-nership by the
Bush administration, while politically useful, leave America spewing
one quarter of the world’s 6.5 billion tons of carbon into
the atmosphere in a “business as usual” stance for the
foreseeable future. Because the amount of CO2 added [by us] exceeds
the amount removed [by Nature], the concentration of atmospheric
CO2 continues to increase annually, and the added carbon remains
in the atmosphere for decades. Even if all nations on the planet
stabilized our release of CO2 emissions to steady-state, the concentration
of “greenhouse” gases would continue to rise for the
rest of the century, and the average global temperature would
increase in response. The severity depends on how quickly we
act.
The utility of this particular issue
of “SCIENCE” was
in the selection of topics that surround the hydrogen economy issue.
The first article, entitled: “The Hydrogen Backlash”,
by Robert Service, warned that transition to a hydrogen economy,
if it comes at all, won’t happen soon, perhaps not until the
second half of the century. Each of the problems to be solved, -
production, storage, fuel cell cost, safety and infrastructure – would
be difficult enough on its own, but to solve them simultaneously,
as would be required for success, would be extremely unlikely. A
chemical engineer at MIT was quoted as saying, “The hype has
been way overblown. It’s just not thought through.” To
combat the warming threat, funding agencies should place a near-term
priority on promoting energy efficiency, renewable research,
and development of hybrid cars.
The second article, also written
by Robert Service, was aptly titled “The Carbon Conundrum”. The theme here was that
even if the hydrogen economy were technically and economically feasible
today, weaning the world off carbon-based fossil fuels would still
take decades. During that time, carbon combustion would continue
to pour greenhouse gases into the atmosphere – unless scientists
find a way to capture and store or sequester unwanted carbon
dioxide.
Although no-one has adapted this
strategy on a large scale, it just happens that oil companies
have been piping CO2 underground
for decades, in order to extract more oil from wells by reducing
the viscosity of under-ground oil. Until 10 years ago, companies
didn’t bother to track whether the CO2 remained underground
or caused unwanted side effects. More recently energy specialists
began to realize that storing CO2 underground into depleted oil
and gas reservoirs may be the least harmful solution, albeit
short-term, for storing unwanted CO2.
At first, it sounded like a wild idea, partly because the volume
of gas that would have to be stored is enormous. For example,
storing just 1 Gigaton of
CO2 – about 48% of what we vent every year around the globe – would
require moving 4.8 million cubic meters of CO2 a day. (That is equivalent to
about one third of the volume of all the oil shipped daily around the globe!)
But preliminary studies suggest that there is enough underground capacity to
store hundreds of years’ worth of CO2 injection, and potential storage
sites exist worldwide.
To test the technical feasibility of this strategy, researchers
are teaming up with oil and gas companies to study their CO2 piping
projects. One of the first to be studied is in Saskatchewan, Canada,
where EnCana has launched a $1.5 billion, 30-year effort to pipe
20 million metric tons of CO2 into their reservoir. This is not
pure altruism, since EnCana hopes this will increase the yield of
their field by another third. (They simply use compressors to force
compressed CO2 down a long pipe drilled into the underground reservoir.)
So far, over 5 years, they have locked away nearly 3.5 million metric
tons of CO2 in the Weyburn reservoir.
There are several other equally well-written
viewpoints in that special issue of “SCIENCE”, but the review article by
S. Pacala and R. Socolow (10) is especially relevant. They have
written a prescription for the future, so it resembles Plan B, except
that it is aimed specifically at the problem of global warming.
Their key point is: we already possess the fundamental scientific,
technical and industrial know-how to solve the carbon and climate
problem for the next half-century. By applying a portfolio of existing
technologies to meet the world’s energy needs over the next
50 years, we can limit atmospheric CO2 accumulation to a lower
trajectory that might avoid otherwise devastating effects.
The first of 15 strategies discussed
in this review is the use of efficient vehicles. Let us suppose
that the world’s
fleet of cars and trucks expands by ~4-fold over the next 50
years to
2 billion units. Without a focus on carbon we might improve our
fuel economy to an average of 30 miles per gallon (mpg). However,
with the use of hybrid vehicles it is now possible to achieve
60 mpg, and future advances should allow us to bring the entire
global
fleet to that level over the next 50 years. If we accomplished
this goal by 2055, we would reduce the carbon emission rate
by 1 gigaton
per year, or by 25 gigatons over 50 years.
Such large numbers as gigatons of
carbon are difficult to grasp conceptually. To fully appreciate
the value of automobile
efficiency,
consider these statistics: Improving the efficiency of the automotive
fleet - just in USA – by 1 mpg would save twice the amount
of oil that could ever be harvested from ANWR (Arctic National
Wildlife Reserve). Further improvement by 8 mpg would avoid our
need to import
oil from any Arabian gulf country. Future enlargements of the
global car fleet will come primarily from China and India, where
hybrid
technology can be employed very effectively.
A second strategy would be to persuade
people to reduce vehicle use from an average of 10,000 miles/year
to 5,000 miles/year.
This
will require altruism from people who are already quite addicted
to the “freedom” of individual travel in automobiles.
However, increased traffic congestion and/or gasoline taxes may
motivate more people to use mass transit. Other gains can be
achieved from telecommuting and from improving urban design to
promote walking
instead of driving.
The remaining 13 strategies are equally important, but they require
leadership from all of our elected officials. They include: use
of more efficient heating and cooling in buildings and appliances,
use of less fossil fuels and more sustainable fuels in our power
plants, and the capture and underground storage of CO2 in empty
oil and gas fields until we can be weaned off the use of fossil
fuels entirely. This will require the installation of millions more
wind turbines and photovoltaic power units, and perhaps, if absolutely
necessary, some nuclear power plants as well. All this would be
aided if we could stop tropical deforestation and plant new trees.
Most important, the longer we delay to take these actions, the more
difficult the transition will be (11).
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