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The promise of carbon capture and storage

ExxonMobil leads in one of the most important next-generation technologies: carbon capture and sequestration (CCS).

CCS is the process by which carbon dioxide gas that would otherwise be released into the atmosphere is separated, compressed and injected into underground geologic formations for permanent storage. The Intergovernmental Panel on Climate Change estimates that fossil fuel power plants and large industrial facilities account for as much as 60 percent of global carbon emissions. Thus, broad-based deployment of cost-effective carbon capture and sequestration has the potential to make a massive impact on the world’s greenhouse gas levels.

Currently, making use of CCS to reduce significant amounts of emissions is prohibitively expensive. However, ExxonMobil uses the technology during enhanced oil recovery, injecting captured and compressed carbon dioxide into depleted oil wells to make them more productive. This experience, combined with ongoing research and sequestration partnerships means that CCS may well become a viable and important emissions reduction option in the near future in large part due to what ExxonMobil is doing today.

ExxonMobil has a working interest in more than one-third of the world’s current carbon capture and sequestration capacity. We captured more than 6 million metric tons of carbon dioxide for sequestration in 2014 alone. This is the equivalent of eliminating the annual greenhouse gas emissions of more than 1 million passenger vehicles. The potential of this technology, however, is many times greater.

ExxonMobil’s commitment to advancing CCS technology

Achieving meaningful reductions in greenhouse gas emissions will require a wide range of solutions in the coming years. ExxonMobil believes that CCS has the potential to play an important role in managing GHG emissions, but it will require additional technological breakthroughs, fully integrated demonstration projects, regulatory and legislative support at all levels, and public acceptance.

With its long history of operational, technical and research experience in the technologies comprising CCS, ExxonMobil is uniquely positioned to lead the way in further development of this promising approach to reducing emissions.

Our involvement includes:

  • Partnering with the European Commission and other companies on the CO2ReMoVe project that evaluated a range of technologies to monitor the injection and storage of CO2 from gas streams in fields around the world.
  • Collaborative research at the International Energy Agency, Massachusetts Institute of Technology, Georgia Tech, University of Texas and University of Wyoming.
  • Participation in U.S. Department of Energy Regional Sequestration Partnerships.
  • Intensive internal research and development of CCS-related technologies and participation in demonstration projects.
  • Co-founder of the Global Climate and Energy Project (GCEP) at Stanford University, a long-term research program designed to accelerate development of a range of commercially viable energy technologies that can lower GHG emissions on a global scale.

Verifying the integration and performance of capture, transportation and storage technologies in large-scale CCS applications is a vital step toward deployment of CCS systems.

The scale, significant investment and required new infrastructure cannot be overlooked. They also remain barriers to widespread deployment of CCS. The concept includes potentially duplicating the oil and gas industry’s infrastructure – which has been built over 100 years – in a third of the time. In addition, the increased energy demand will result in competition (energy industry vs. CCS) for the same skilled workforce. CCS is also not likely to be economically justified without some predictable means for placing a value on emitted carbon or a clear regulatory and legal framework.

CCS has the potential to reduce global CO2 emissions. Emission reduction is an issue that warrants action, since if left unchecked, global emissions are expected to continue to rise. But CCS is not the perfect answer.

Carbon capture and storage

Step 1: Capturing CO2
The first step in the CCS process is capturing, or separating, the CO2 from the fuel source used at power generation plants or industrial manufacturing facilities. Capture is the most costly and energy-intensive step of the CCS process.

ExxonMobil has extensive experience in separating CO2 from hydrocarbons through its natural gas processing facilities, which remove impurities from the gas before it is shipped via pipeline.

Most current capture technologies use a solvent to remove CO2 from the gas stream, but ExxonMobil’s Controlled Freeze Zone technology, currently undergoing commercial-scale demonstration, is based on the freezing and re-melting of CO2 in a modified distillation column. Controlled Freeze Zone technology reduces the cost and complexity of separating CO2 from natural gas and could have significant benefits for CCS systems, in part because there are no limits on CO concentration, and the CO2 is discharged under pressure, ready for re-injection.

One key to successful implementation of CCS on a commercial scale is developing cost-effective solutions for capturing CO2 from coal-fired power generation plants. This is an area where a great deal of research is under way.

Step 2: The transportation process
The second step is transporting the captured CO2 to the storage site – underground geologic formations such as depleted oil or gas reservoirs.

ExxonMobil Pipeline Company operates or has an interest in 18,000 miles (29,000 kilometers) of pipeline in the United States, using the most advanced technology and extensive quality-control procedures to ensure the safety of its lines. The company’s integrity management program includes a wide range of testing and monitoring techniques – from hydrotesting to tools that travel through the pipeline to inspect for flaws or ongoing corrosion control. In addition to these inspection and maintenance measures, the company’s Operations Control Center monitors pipeline operations on a 24-hour basis.

ExxonMobil is currently involved in a number of research projects designed to test the integrity of steel and other materials when exposed to CO2.

Step 3: Injection and storage
The third and final component of CCS is injecting CO2 into underground reservoirs for storage. ExxonMobil is well versed in this area, due to the company’s long history of using water, natural gas and CO2 injection for EOR and sound resource management.

The company’s field-tested program of injection well integrity management includes mechanical testing, corrosion control programs and computer controlled systems.

ExxonMobil has extensive technological expertise in monitoring and ensuring the integrity of our fields. Our involvement in CO2 injection projects in the North Sea and LaBarge, Wyoming, gives the company first-hand knowledge and experience in this stage of the CCS process.

ExxonMobil’s long-term experience in CCS components

For more than 30 years, ExxonMobil engineers and scientists have researched, developed and applied technologies that could play a role in making CCS viable in commercial applications. For example, our patented Controlled Freeze Zone technology is a single-step process that could more efficiently separate CO2 and other impurities from a natural gas stream. It has the potential to make CCS more affordable.

ExxonMobil has utilized advanced technology and extensive quality-control procedures to ensure facility integrity when designing and developing world-class gas treatment plants, pipelines and injection projects.

We have a history of proven results in a production process called Enhanced Oil Recovery (EOR), which involves injecting CO2 into a reservoir to extract “trapped” oil and gas that could not otherwise be produced. In the United States alone, more than 11 trillion cubic feet of CO2 have already been used in EOR projects.

This technological expertise in the three main components of CCS is currently being put to use in a number of initiatives designed to help ExxonMobil better understand the unique challenges that must be overcome for CCS to be implemented commercially.

For example, ExxonMobil is working with partners on a number of CCS-related research projects, such as improved capture technology; reservoir flow modeling; geologic storage and integrity modeling; and assessing well seal integrity and storage capacity of oil and gas reservoirs, aquifers and coal beds for potential storage use.

In 2008, ExxonMobil captured nearly 4 million metric tons of CO2 at LaBarge, Wyoming that was marketed for EOR and other industrial uses – more captured CO2 than any other similar project in the world. In addition, ExxonMobil is involved in a CCS project in the North Sea in which CO2 is separated from natural gas produced by offshore wells and reinjected into a saline aquifer; more than 15 million metric tons of CO2 have been safely stored underground as part of the project. These real-world activities are especially useful in understanding the steps necessary to move CCS forward.

Infrastructure for widespread deployment

Storing 1 billion tons per year of CO2 is roughly equal to the United States’ annual consumption of natural gas. Consider the natural gas pipeline grid as an example of necessary infrastructure: more than 210 natural gas pipeline systems; 302,000 miles of transmission pipelines; and more than 1,400 compressor stations that maintain pressure on the pipeline network and assure continuous forward movement of supplies, among numerous other elements.

Case study: Gaining confidence in CCS through EOR