**TESTIMONY OF DR. GEORGE GUTHRIE**

**PROGRAM DIRECTOR, FOSSIL ENERGY AND ENVIRONMENT PROGRAMS**

**LOS ALAMOS NATIONAL LABORATORY**

**BEFORE THE SENATE COMMITTEE ON ENERGY & NATURAL RESOURCES**

**APRIL 16, 2007**

Chairman Bingaman, Senator Domenici, and Members of the Committee, thank
you for the opportunity to present testimony regarding the proposed
legislation on the capture and geologic storage of carbon dioxide.

My name is George Guthrie and I am a geochemist. I have been working on
various aspects of CO~2~ for the last 10 years. And, currently I am
program director for fossil energy and environment programs at Los
Alamos National Laboratory.

As you know, fossil fuels are central to the global energy portfolio,
and they are likely to remain so for at least decades. Geologic
sequestration of carbon dioxide offers great global potential to manage
carbon emissions from fossil fuels.

We already have experience with some aspects of geologic sequestration.
The U.S. leads the world in the technology of CO~2~ injection to recover
oil from depleted reservoirs---a process known as enhanced oil recovery
or EOR. Power-plant-scale volumes of CO~2~ have been handled,
transported, and injected into geologic reservoirs for more than 30
years as part of EOR operations in the Permian basin of West Texas.

More recent international efforts include the Weyburn project in Canada
and the Sleipner project in Norway, both of which involve large-scale
CO~2~ injection.

From this experience base, we know that we can handle and inject CO~2~
at volumes equivalent to the output of power plants.

So, what questions remain to be addressed? First, large-scale CO~2~
capture at power plants must be developed and understood. Second, our
storage capacity estimates must be improved by detailed geologic
studies. Third, large-scale CO~2~ injection must be demonstrated under
the variety of conditions anticipated for sequestration. Finally, we
need to verify the long-term safety and reliability of storage sites,
which will require a robust risk assessment framework.

Each of these issues is important. But in my remaining time, I would
like to elaborate on risk assessment.

Risk assessment is particularly challenging due to the implementation
scale, both in terms of CO~2~ volumes and in terms of the time scales
necessary for effective storage. Consequently, risk assessments must be
science based. Some of the scientific base can come from laboratory
experiments and theoretical studies. However, large scale field studies
are the only option for some of the essential data. These sites fall
into two broad categories: large-scale injection demonstrations and
analog sites, which include large natural accumulations of CO~2~ and
industrial sites like EOR operations.

Analog sites provide information on long-term concerns---namely those
that pertain to the fate and impact of CO~2~. Wellbores are an excellent
example. They are a critical component of the containment system. They
are used to place the buoyant CO~2~ below an impermeable barrier. The
problem is that wellbores use cement that may degrade when exposed to
CO~2~ and water.

As part of our support for DOE's carbon sequestration program, we
recently completed the first field-based study of this issue using
samples from a mature EOR site. The results show that interactions do
occur, but complete degradation may not be an issue for some geologic
environments. In fact, in some cases, beneficial reactions may actually
improve the integrity of the wellbore. We need more studies on
wellbores, but these results demonstrate the importance of field
observations in developing a reliable risk framework.

Some data for risk assessment must be collected from large-scale
demonstration projects. Consider the impacts associated with injection
at a CO~2~ storage operation: In EOR, CO~2~ is injected into a reservoir
where fluids have been, and continue to be, removed. In a storage
operation, CO~2~ may be used to displace pre-existing reservoir fluids,
which creates different physical conditions. Large-scale demonstration
projects from a wider range of geologic environments are critical to
address issues, like these, that are unique to CO~2~ storage.

In closing, I want to emphasize that moving forward with carbon
sequestration research is a positive step for the nation. We are at a
point where many of the remaining questions can only be answered by
larger field efforts. We know we can handle and inject CO~2~ safely at
large volumes. But, we need to show that CO~2~ capture at power plants
works. We need to improve our estimates on the overall capacity for
geologic storage. And, we need to develop the confidence that CO~2~
storage is a safe and effective option for the long-term. The work
proposed in this legislation is critical in moving geologic
sequestration from a good concept to a meaningful option.