Issues in Science and Technology
November 15, 2005


The technology is advancing rapidly; now the government needs to lead
the push for deployment.

Jennie C. Stephens and Bob van der Zwaan

Human activity spills about 25 billion tons of carbon dioxide (CO2)
into the atmosphere every year, building up the levels of greenhouse
gases that bring us ever closer to dangerous interference with Earth's
climate system. The world's forests take up about 2 or 3 billion tons
of that output annually, and the ocean absorbs 7 billion tons. Experts
estimate that another 5 to 10 billion tons of this greenhouse gas--as
much as 40% of human-made CO2--could be removed from the atmosphere
and tucked safely away.

Advancing the technologies needed to capture and store CO2 is a
sensible strategy. In addition to increasing renewable energy and
promoting energy efficiency and conservation, the strategy of
advancing CO2 capture and storage (CCS) can be easily understood by
all Americans who acknowledge that even though fossil fuels will be
needed for a long time to come, the U.S. government at some point must
confront the climate change problem by setting limits on CO2

Capturing and storing CO2 is a cost-competitive and safe way to
achieve large-scale reductions in emissions. CCS technology offers a
unique opportunity to reconcile limits on CO2 emissions with society's
fossil fuel-dominated energy infrastructure. In order to continue
using the United States' vast domestic coal resources in a world where
CO2 must be constrained, the country will need to rely on technology
that can seize CO2 generated from coal-fired power plants and store it
in geologic formations underground. However, the integration and
scaling up of existing technologies to capture, transport, and store
CO2 emitted from a full-scale power plant have not yet been
demonstrated. The technical feasibility of integrating a complete CCS
system with a commercial-scale power plant is not in doubt, but it is
necessary to build up experience by advancing early deployment.

In addition to the environmental benefits, more aggressive support of
CCS technology is critical to maintaining U.S. leadership and
competitiveness in both CCS and global energy-technology markets. The
United States has played a leading role in nearly all R&D related to
the use of fossil fuels and has always had particular expertise in
coal-based power-production technologies. Yet despite the great
potential of CCS, the U.S. government is not investing in it
aggressively. The current administration emphasizes the importance of
advanced technologies, including CCS, in addressing climate change,
but is not effectively promoting its demonstration and deployment.

U.S. industry is already beginning to lose ground, because the handful
of existing large-scale CCS projects are not in the United States.
The private sector has shown substantial interest in CCS and has begun
investing in development and demonstration projects. But progress will
be slow without government-created incentives. The challenge for the
government is to harness the private sector's interest by developing
policies that reward investment in and early deployment of CCS

The state of the art

Large stationary sources of CO2 are good candidates for CCS. Power
plants are the largest emitters, generating 29% of CO2 emissions. The
gas also can be captured from some large-scale industrial processes
that release lots of CO2, including the production of iron, steel,
cement, chemicals, and pulp; oil refining; natural gas processing; and
synthetic fuels production. Small nonpoint sources of CO2, including
emissions from vehicles, agriculture, and heating systems in
buildings, are not good candidates for CCS because there currently is
no way to capture the CO2 from these dispersed sources.

A complete CCS system relies on three technological components:
capture, transport, and storage. Technologies that are used
commercially in other sectors are available for each of these
components. CO2 capture technology is already widely used in ammonia
production and other industrial manufacturing processes, as well as
oil refining and gas processing. CO2 gas has been transported through
pipelines and injected underground for decades, most notably in west
Texas, where it is used to enhance oil recovery from wells in which
production is declining. In addition, some 3 to 4 million tons of CO2
per year is stored underground at several locations in other

CO2 capture technologies can be divided into three categories: post-
combustion or "end-of-pipe" CO2 capture, relying on chemical or
physical absorption of CO2; pre-combustion CO2 capture technologies
that separate CO2 from a syngas fuel (produced from coal, oil, or
natural gas) before the fuel is burned; and oxyfuel combustion, in
which oxygen instead of air is introduced during the combustion
process to produce a relatively pure stream of CO2 emissions.

Of these options, pre-combustion capture is currently the most
efficient and therefore the cheapest. In the case of coal-fired power
plants, however, pre-combustion capture can be applied only when coal
gasification technology is employed, such as in integrated
gasification combined-cycle coal-fired power plants.

Once the CO2 is separated and captured, it must be compressed to
reduce the volume of gas for transportation to an appropriate storage
location. Compressing gas uses a lot of energy; so this part of the
CCS system adds to the overall implementation costs. CO2 can be best
transported by pipeline or ship. Ships are cost-effective only if the
CO2 must be moved more than 1,000 miles or so. A network of CO2
pipelines is already being used in several areas of the United States
for enhanced oil recovery, so building and operating CO2 pipelines is
unlikely to pose technical or safety challenges. But regional siting
limitations are possible.

Three alternative approaches to storing CO2 in a reservoir other than
the atmosphere have been proposed: geological storage, storage in the
ocean, or aboveground land storage. Geologic storage is currently the
most promising approach. It involves direct injection of CO2 into
underground geologic formations, including depleted oil and gas
reservoirs, unminable coal seams, and deep saline aquifers. Public
opposition to the idea of injecting CO2 directly into the deep ocean
has prevented some research on this option, despite the ocean's
natural capacity to store most of the CO2 currently emitted into the
atmosphere. The potential of aboveground land storage is limited by
the impermanence and short (decade-long) time-scale of carbon storage
in biomass and the slow reaction rates associated with the formation
of carbonate minerals.

The oil industry has substantial commercial experience with CO2
injection to enhance oil production. That experience provides support
for exploiting the many opportunities for coupled enhanced oil
recovery/CO2 storage. At Weyburn in Saskatchewan, CO2 has been
injected underground since 2000 for the dual purpose of enhancing oil
recovery and storing CO2. Interest in storing CO2 in other underground
reservoirs, including aquifers, has been increasing rapidly. Both the
private and public sectors have contributed support to a handful of
underground CO2 storage projects that are not intended to enhance oil
recovery. At Sleipner in the North Sea, the Norwegian national oil
company Statoil has been injecting CO2 separated out from the
production of natural gas into a saline aquifer since 1996. In the
fall of 2004, at In Salah in Algeria, BP similarly began injecting CO2
separated from the extracted natural gas back into the gas reservoir.
Several other projects of even greater scale than these existing ones
are planned in Australia, Germany, and the United States in the next
few years.

Risks and uncertainties

The dominant safety concern about CCS is potential leaks, both slow
and rapid. Gradual and dispersed leaks will have very different
effects than episodic and isolated ones. The most frightening scenario
would be a large, sudden, catastrophic leak. This kind of leak could
be caused by a well blowout or pipeline rupture. A sudden leak also
could result from a slow leak if the CO2 is temporarily confined in
the near-surface environment and then abruptly released.
CO2 is benign and nontoxic at low concentrations. But at high
concentrations it can cause asphyxiation, primarily by displacing
oxygen. The most noteworthy natural example of a catastrophic CO2
release was in the deep tropical Lake Nyos in Cameroon in 1986.

Lake water that was gradually saturated with CO2 from volcanic vents
suddenly turned over and released a huge amount of the gas; the CO2
cloud killed 1,700 people in a nearby village. An event like this can
occur only in deep tropical lakes with irregular turnover, but it is
conceivable that leaking CO2 could infiltrate caverns at shallow
depths and then suddenly be vented to the atmosphere.

CO2 is denser than air, so when released it tends to accumulate in
shallow depressions. This increases the risk in confined spaces close
to the ground, such as buildings and tents, more than it does in open
terrain, where CO2 will diffuse quickly into the air.
Before any CO2 storage project will be allowed to begin, it will have
to be demonstrated to regulators that the likelihood of rapid leakage
is negligible and that any gradual leakage will be extremely slow.
Also, monitoring and verification procedures will be able to detect
potential leaks.

In addition to undermining the purpose of a storage project, CO2
leakage from an underground reservoir into the atmosphere could have
local effects: ground and water displacement, groundwater
contamination, and biological interactions. Monitoring technology that
can measure CO2 concentrations in and around a storage location to
verify effective containment of the gas has demonstrated that leakage
back to the atmosphere has not been a problem in current CO2 storage

Leakage from a naturally occurring underground reservoir of CO2 in
Mammoth Mountain, California, provides some perspective on the
potential environmental effects. The leaking led to the death of
plants, soil acidification, increased mobility of heavy metals, and at
least one human fatality. This site is a useful natural analog for
understanding potential leakage risks, but Mammoth Mountain is
situated in a seismically active area, unlike the sedimentary basins
where engineered CO2 storage would take place. Still, we should be
wary of undue optimism and continue to question the safety of
artificial underground CO2 storage. Given potential risks and
uncertainties, the implementation of effective measurement,
monitoring, and verification tools and procedures will play a critical
role in managing the potential leakage risks of all CO2 storage

Because of the high degree of heterogeneity among different geologic
formations, the current set of CO2 storage projects is not necessarily
representative of other likely storage locations. More demonstration
projects are needed in different geologic areas. Some preliminary work
has been done to understand the global distribution of appropriate
underground reservoirs. But the regional availability of storage
locations has not yet been well characterized, although this will be
critical in determining the extent of possible CCS deployment
throughout the world. Significant expansion of the number of CO2
storage projects and continued research on the mobility of the
injected CO2 (and the risks associated with its leakage) should be
high priorities.

To reduce the risks associated with CO2 leaks, it is possible to
choose "smart storage" sites first. Aquifers and depleted oil and gas
fields under the North Sea, for example, provide a relatively safe
opportunity for initial large-scale deployment. Risks associated with
leakage from geologic reservoirs beneath the ocean floor are less than
risks of leakage from reservoirs under land, because if the
containment falters, the dissipating CO2 would diffuse into the ocean
rather than reentering the atmosphere.

The United States is doing little to advance the deployment of CCS
technologies, but the government did spend about $75 million in 2004
on R&D. The primary goal of the core CCS R&D program is to support
technological developments that will reduce implementation costs. In
addition, the Department of Energy supports--with a $100 million
budget over four years--a Regional Sequestration Partnership program
that stimulates region-specific research designed to determine the
most suitable CCS technologies, regulations, and infrastructures, as
well as to assess best management practices and public opinion issues.
It will also develop a database on potential geologic storage sites.
The purpose of this partnership is to bring CCS technology from the
laboratory to the field-testing and validation stage.

The United States has also initiated one large-scale demonstration
project, FutureGen, to investigate the technical feasibility and
economic viability of integrating coal gasification technology with
CCS. FutureGen, launched in 2003 with a projected budget of some $1
billion, was supposed to be the first demonstration of a commercial-
scale coal-fired power plant that captures and stores CO2. But no site
has yet been selected, and funding for the construction phase has not
been allocated. FutureGen's future is uncertain.

Thus, although the government is supporting some CCS R&D and has
initiated planning of one large-scale CCS demonstration project, none
of the current efforts provide the incentives necessary for the
private sector to begin deployment.

Economics will largely determine whether CCS can compete with carbon-
mitigating energy alternatives. Despite the extensive commercial
experience with technological components in other applications,
minimal experience in integrating capture, transport, and storage into
one system so far means that current cost projections are quite

For power plants using modem coal gasification combined-cycle
technology or a natural gas combined cycle, the costs of capturing,
transporting, and storing carbon dioxide are estimated at about $20 to
$25 per metric ton of CO2. For plants using traditional pulverized
coal steam technology, these costs could double.

CO2 capture technology is itself energy-intensive and requires a
substantial share of the electricity generated. Accounting for the
corresponding power plant efficiency reduction (up to 30%) by
expressing costs in dollars per ton of CO2 avoided, the costs of CCS
in power plants range from $25 to $70 per ton of CO2 avoided. These
figures imply an additional 1 or 2 cents per kilowatt hour (kWh) for
new coal gasification power plants, which have a baseline cost of
about 4 cents per kWh.

Currently, these cost estimates are dominated by the cost of capture
(including compression). If transport distances are less than a few
hundred miles, the cost of capture constitutes about 80% of the total
costs. The broad range of current cost estimates for CCS systems
results from a high degree of variability in site-specific
considerations. Among these are the particular power plant technology,
transportation distance, and storage site characteristics. For all
power plant alternatives and components, costs are expected to decline
as new technologies are developed and as more knowledge is gained from
demonstration projects and early deployment efforts.

But if the United States does not step up efforts to advance CCS
deployment, the cost reductions from learning by doing will not emerge
soon. In addition, growing experience and expertise in other countries
could reduce U.S. competitiveness in CCS.

European leadership in CCS deployment began in 1996, when the
Norwegian government instituted a tax on CO2 emissions equivalent to
about $50 per ton of carbon avoided. This tax motivated Statoil to
capture the CO2 emitted from its Sleipner oil and gas field and inject
it into an underground aquifer. More recently, the British government
has taken the lead on CCS deployment by announcing ?40 million to
support CO2 storage in depleting North Sea oil and gas fields. This
effort was initiated a month before the July 2005 G8 summit, where its
chairman, British Prime Minister Tony Blair, advocated increased
governmental support for developing carbon-abatement technology as a
critical part of confronting climate change.

Injecting CO2 to enhance oil and gas recovery in the North Sea is not
commercially viable without government support. But given the high
costs of decommissioning these production wells and the economic
benefits associated with retaining jobs and extracting more oil and
gas, the British have recognized an opportunity. By providing support
for CO2 storage, the British are simultaneously advancing CCS
technology, potentially offsetting decades of European CO2 emissions,
and extending production of the oil and gas fields for several more
decades. Opportunities for early deployment of CCS also exist for
other European nations with declining production of oil and gas wells
in the reservoirs beneath the North Sea. Denmark, the Netherlands, and
Norway may initiate programs similar to those of the British soon.

Climate policies being implemented and refined in the European Union
(EU) and other countries that signed the Kyoto agreement to reduce
greenhouse gas emissions provide some incentive for CCS, so more
large-scale CCS projects are imminent. The practical experience
obtained through this deployment will elevate the countries and
companies involved in these projects to leaders in developing,
improving, and exporting CCS technologies.

The United States has recognized efforts elsewhere in the world to
advance CCS, so in 2003 it initiated the Carbon Sequestration
Leadership Forum, a venue for international collaboration among its 17
member states. It facilitates joint projects and communication about
the latest developments in CCS technology. But the United States could
be doing a lot more in the international arena than simply
facilitating communication. The stakes are too high not to adopt
aggressive strategies for domestic CCS deployment as well.
In the absence of large-scale domestic CCS implementation, the United
States is likely to lose its current leadership position in frontier
fossil-fuel expertise. Even if no meaningful climate policy
materializes in the United States in the near term, the CCS market
will grow. If the United States wants to maintain a leadership role in
CCS technology, it will need to begin deployment soon.

Balancing R&D, demonstration, and deployment

CCS is only one set of technologies with the potential to contribute
to stabilizing CO2 emissions. Two seemingly polar opinions predominate
about technology for reducing emissions. One side argues persuasively
that because humanity already possesses the technological know-how to
begin solving the climate problem, the focus should be on implementing
all existing methods and technologies. The other side argues that
because we have not yet developed sufficient non-CO2-emitting energy
technologies, what we need are revolutionary changes in energy

But in fact this is a misleading dichotomy. It exists largely because
different time scales implicit in each view have not been
appropriately reconciled and correctly associated with corresponding
parts of the CO2 concentration stabilization path. During the first 50
years of CO2 stabilization, emissions need only be maintained at their
current level. Existing technologies can be implemented to achieve
this initial part of the stabilization path. Beyond 50 years,
atmospheric CO2 stabilization requires steep emission reductions. We
do not yet have the technologies to achieve this, so undertaking
intensive energy R&D is a necessity.
Thus, the view that we have a portfolio of existing technologies that
allow us to start today on the path toward stabilization actually
complements the view that new technologies will be required to
maintain that stabilization path beyond 50 years. The critical
question now is not whether to combine R&D, demonstration, and
deployment efforts, but rather how to balance limited resources among

Interestingly, technologies associated with CCS can fit comfortably
into the spectrum of opinion about how to achieve reduced emissions.
Three of the 15 potential changes involving existing technology
proposed by Stephen Pacala and Robert Socolow in a 2004 Science
article involve capturing CO2 and storing it in underground
formations. Geologic storage of carbon released from fossil-fuelled
energy production is one of the potential carbon-emission--free
primary energy sources identified in a 2002 Science article by Martin
Hoffert et al. as needing R&D to overcome limiting deficiencies in
existing technology. CCS is thus a set of technologies and concepts at
varying stages of readiness.

Although the federal government should continue and increase its
support for R&D to improve CCS technology and identify the best
storage sites, the most critical and immediate requirement for
advancing CCS technology is incentives for companies to begin early
deployment. Private-sector interest in CCS is growing rapidly,
demonstrating an increasing acceptance of the idea that CCS
technologies are going to play a role in future energy production.
Many companies in the oil and gas industry are already beginning to
invest in and prepare for CCS deployment. The most recent came in June
2005, when BP and several industry partners announced plans to build
the world's first integrated commercial-scale power plant with CO2
capture and storage. The project involves a 350-megawatt power plant
in Scotland, from which CO2 will be captured and then transported to
the North Sea, to be injected into underground reservoirs for storage
plus enhanced oil recovery.

Most current industry projects receive some government support. The
most recently initiated CO2 storage project, in In Salah, Algeria, is
a joint venture with BP, Sonatrach (the Algerian national energy
company), and Statoil. The Sleipner CO2 storage project has some
support from the EU, and the Weyburn project is funded by the Canadian
government. Because of the level of interest and the fact that there
is so much to learn, various organizations have been involved in many
of the existing projects.

In the United States there are similar opportunities. But without a
regulatory framework to provide incentives for reducing CO2 emissions,
companies remain hesitant. The high cost of CCS deployment, as well as
the large scale and the complex integration of CCS technologies with
existing energy infrastructures, means that the private sector will
not act without clear government rules and support. Just as it has in
Europe, U.S. government-coordinated demonstration or early-deployment
CCS projects with commercially motivated enhanced oil recovery would
provide a cost-effective early opportunity for advancing CCS.

Unlike other emerging energy technologies that would compete with the
existing fossil fuel infrastructure, CCS provides a way for fossil
fuel industries to reconcile continued use of these fuels with climate
change mitigation. But to guide the fossil fuel industries toward CCS,
the government must set limits on CO2 emissions. The fossil fuel
industries have evolved and grown under the assumption that there is
no cost associated with emitting CO2. Government limits will force
them to reorder their priorities and investments.

There are various approaches to regulating CO2, but the broadest
support exists for a cap-and-trade system. This approach was recently
endorsed by the National Commission on Energy Policy and is also the
approach incorporated into the proposed McCain-Lieberman Climate
Stewardship Act.

Incentives for early deployment are the most critical requirements for
advancing CCS. Given the increasing technical feasibility of CCS, the
country needs experience at the commercial scale and the associated
learning by doing as soon as possible. Right now, early deployment is
more important than widespread deployment, because much will be
learned from an initial set of full-scale CCS operations, and those
lessons will influence more advanced deployment.

Demonstration is a critical component of technology innovation, so
increased funding for demonstration projects is essential to the
advancement of CCS technology. Large-scale demonstration projects
should be government/industry partnerships, with seed money coming
from government and substantial contributions coming from
participating companies. The goals and parameters of each project, as
well as the mechanisms for learning from the experience and evaluation
methods, should be developed jointly by government and industry.
Companies should take the lead on implementation because of their
expertise in large-scale projects.

The increasingly precarious FutureGen project was developed to be the
first fully integrated demonstration effort, but its slow progress and
uncertain future have been frustrating. This discouraging history
suggests that earmarking such a large proportion of the government's
total CCS funds for one ambitious commercial-scale power plant is not
an efficient use of resources. The demonstration of capture technology
in existing power plants or the integration of capture technology in
the design of several of the new power plants built in the next few
years could be a cheaper way to achieve operational proficiency and to
realize overall CCS cost reductions through learning by doing.
In addition to demonstrating CO2 capture technology in commercial-
scale power plants, we need more large-scale CO2 storage demonstration
projects in a diverse set of locations in order to get experience in
geologically heterogeneous reservoirs, both in the United States and
elsewhere. The lessons derived from these additional projects would
strengthen the case for geologic storage and provide additional
information on safety and environmental concerns.
Detailed regional maps of storage potential need to be developed
throughout the world. Geologic assessments are needed particularly in
China, India, and other coal-rich developing countries. Their rapid
economic growth is associated with dramatic increases in CO2
emissions, and the potential for CCS in these countries has not yet
been assessed systematically. The level of U.S. action on CCS
technology will affect global understanding of the potential for CCS
in developed and developing countries and could influence energy
technology choices in these countries.

Although the U.S. government continues to abstain from setting limits
on CO2 emissions, companies are making critical technical decisions
that will have enormous impacts on future emissions. In the United
States, the high prices of natural gas and the abundance of domestic
coal have increased pressure to build more coal-fired power plants. If
CO2 reduction regulations are instituted soon, these will encourage
the deployment of technologies to capture and store CO2 from those
plants. The United States could begin to reduce its global CO2 burden
while at the same time becoming a leader in the rapidly emerging
market for carbon-abatement technologies.
For more than 20 years, San Francisco Bay area artist and photographer
David Maisel has photographed terrains from low flying planes,
creating images that are both beautiful and disturbing at the same
time. His most recent project, a sample of which is reproduced here,
is entitled Terminal Mirage and focuses on and around the Great Salt
Lake in northwestern Utah. In his work, Maisel intentionally obscures
the function, location and scale of his subject in order to create a
tension between the aesthetic appeal of the image and the often
disturbing narrative of the subject matter.

For more information on David Maisel, his work, and upcoming
exhibitions, please visit

Recommended reading

S. Anderson and R. Newell, "Prospects for Carbon Capture and Storage
Technologies," Annual Review of the Environment and Resources 29
(2004): 109-142.

J. Bradshaw and T. Dance, "Mapping Geological Storage Prospectivity of
CO2 for the World's Sedimentary Basins and Regional Source to Sink
Matching," 7th International Conference on Greenhouse Gas Control
Technologies, Vancouver, Canada, 2004.

H. Herzog, B. Eliasson, and O. Kaarstad, "Capturing Greenhouse Gases"
Scientific American 282 (2000): 2.

M.I. Hoffert et al., "Advanced Technology Paths to Global Climate
Stability: Energy for a Greenhouse Planet," Science 298 (2002):

International Energy Agency, Prospects for CO2 Capture and Storage
(Paris, France: Organisation for Economic Cooperation and Development
and International Energy Agency, 2004).

S. Pacala and R. Socolow, "Stabilization Wedges: Solving the Climate
Problem for the Next 50 Years with Current Technologies," Science 305
(2004): 968-972.

A. D. Sagar and B. van der Zwaan, "Technological Innovation in the
Energy Sector: R&D, Deployment, and Learning-by-Doing." Energy Policy,
in press.

Robert H. Socolow, "Can We Bury Global Warming?" Scientific American
(July 2005): 49-55.


Bob van der Zwaan is a senior researcher in the Policies Studies
Department of the Energy Research Centre of the Netherlands (ECN) in
Amsterdam and a research associate in Harvard University's Belfer
Center for Science and International Affairs.

Citation: Issues in Science and Technology Vol. 22 no 1 (Fall 2005),
pgs. 68-76.