• INE
• Projects
• Carbon
• CCUS FAQs

Frequently Asked Questions

General CCUS

What is carbon dioxide?

Carbon dioxide (CO₂) is a non-flammable, non-explosive, naturally occurring gas. Humans exhale it with every breath; it is used in hundreds of products including soda, dry ice and fire extinguishers; and is a necessary component of plant growth. It’s the bubbles in your soda or beer.

What happens if carbon dioxide leaks? Does carbon dioxide explode?

Carbon dioxide (CO₂) is not flammable or explosive. Although CO₂ is usually thought of as a gas, to transport it in a pipeline, it is necessary to change the CO₂ from a gas into a special state of matter called a supercritical fluid, which is possible when the temperature and pressure reach a certain range. In the unlikely occurrence CO₂ escaping from a pipeline or through the surface, most of the CO₂ returns to a gaseous state, although it is common to see dry ice (solid CO₂) around the rupture site as well.

Although prolonged exposure to high concentrations of CO₂ can cause breathing difficulty, the gas typically quickly evaporates into the air and requires little to no clean-up.

In the event of a leak, pipeline systems are designed to automatically shut down, ceasing all operations until the cause is determined and repaired.

Underground storage sites are monitored and in the unlikely event of a leak, wells are remediated, and operating practices are modified to prevent future leaks.

Why do we call it carbon capture, CCS, or CCUS?

Carbon capture is the act of separating carbon dioxide (CO₂) molecules from the exhaust or flue gas of an industrial facility such as a power plant or ethanol plant; this is known as point source capture (PSC). Carbon capture can also be removing CO₂ directly from the atmosphere, which is known as Direct Air Capture (DAC). 

In Carbon dioxide Capture with Storage or Sequestration (CCS), captured CO₂ is injected deep underground (nearly a mile or more) within porous and permeable rock beds, covered by cap rock. With Storage or Sequestration, captured carbon dioxide is permanently removed from the atmosphere. 

In CCUS, the captured carbon dioxide is beneficially Used or Utilized. Uses can include enhanced oil recovery (EOR), medical, carbonating beverages, enhance crop growth in a greenhouse, and other industrial uses.

Image from the Global CCS Institute, CCS 101

Are there successful CCUS projects in Alaska or elsewhere?

Yes, in Alaska, natural gas processing in Prudhoe Bay has concentrated carbon dioxide (CO₂) which ranges from 12.5% CO₂ in the natural gas to around 20% CO₂ for the miscible gas enhanced oil recovery project. Miscible gas is 20% CO₂ with 80% rich hydrocarbon gases including ethane, propane, and butane. The Prudhoe Bay miscible gas project has increased oil recovery from the field by over 500 million barrels of oil—using existing injectors and producing wells and improving overall field recovery. 

The following chart summarizes carbon capture capacity globally in 2023, with 55 million tonnes per year (MMTPA) combined:

From the Decarbonization Channel (Source)

The best indicator of success is increasing project activity and investment around the planet. The following figure from the Global CCS Institute’s 2023 annual report shows commercial facility capacity as of 2023. Investments continue to grow CCS capacity.

Key changes from 2022 to 2023:

• The CO2 capture capacity of all CCS facilities under development has grown to 361 million tonnes per annum (MMTPA) – 48% growth in one year.
• This will be accomplished by 198 new facilities being added to the development pipeline. There are currently 41 projects in operation, 26 under construction, and 325 in advanced and early development.

From the Global CCS Institute, 2023 Annual Report

In North America for example, about 2.5 million tonnes per year is being captured in North Dakota and shipped to Canada for enhanced oil recovery and/or sequestration for about 25 years. CCUS Projects include: 

• In North Dakota, there are three active CO₂ capture projects, 2 ethanol and one coal plant.
• In Alberta, Canada, the Boundary Dam #3 coal-fired electrical power plant has captured about 7 million tonnes of CO₂.
• In Texas, the Petro Nova plant has restarted and is meeting its performance targets, supplying CO₂ to the Hilcorp to enhance oil recovery. 
• There are two coal-fired power plants operating with CO₂ capture in China. The Milton R Young power plant has its permits and plans to begin acquiring equipment, constructing, and starting operations. This is known as Project Tundra. 

Why should we do carbon capture? How is it good for Alaska?

Carbon dioxide (CO₂) capture allows projects to move forward aligned with Policies of Federal, State, and Local governments and with their own corporate goals. For example, by lowering a company’s CO₂ footprint.

For example, we are discussing a new biomass and coal-fired power plant in Southcentral Alaska for the Railbelt. This firm power supply, which could help strengthen the Railbelt system resilience, would probably not be an option for consideration without CCS.

Capturing carbon dioxide earns tax credits of $85 per tonne CO₂ sequestered. If the CCS costs are less than the tax credits, electricity costs with CCS are lower than the cost of electricity without CCS. This is the expectation for the Minnkota Power Cooperative that is supporting Project Tundra on the Milton R. Young Power Plant in North Dakota. This Co-Op expects that CCS will improve the economics and viability of their power plant. 

States are also implementing carbon management policies, in addition to Federal Regulations and EPA rules. Washington, Oregon, and California have all put caps on their refinery gasoline carbon intensity. Crude oil suppliers, including Alaskan companies, now must demonstrate how much carbon dioxide is generated from producing and shipping their crude oil, and lower carbon intensity crude oil is more valuable in those markets. 

Carbon capture and storage is one way that companies can reduce the carbon intensity of their products, which will make them more attractive to West Coast refineries. 

What is the current federal policy on CCUS?

Updates made in the One Big Beautiful Bill passed on July 4, 2025, increased the 45Q credit paid to $85 per ton CO2 for enhanced oil recovery (same as for geologic sequestration) and also indexes the 45Q tax credit dollar amount with inflation. While the bill reduces incentives for renewables, it strengthens incentives for CCS.

What CCUS-related projects are underway in Alaska?

Alaska CCUS activities include the following, as of the third quarter of 2025:

Regulatory

• The Alaska Oil and Gas Conservation Commission (AOGCC) is seeking Class VI injection well primacy from the Environmental Protection Agency (EPA) (SB48, May 2023). Class VI wells are wells designed specifically for injection and storage of carbon dioxide. Gaining primacy over this class of wells would allow AOGCC to directly regulate and oversee the permitting, development, and stewardship of these wells in Alaska, as it currently does with other oil and gas wells in Alaska. For more information, visit the AOGCC website.
• The Alaska Department of Natural Resources (DNR) carbon storage regulations (HB50, July 2024) took effect February 2025. For more information, visit the DNR Division of Oil and Gas website.

Federal DOE Funded Awards

• DNR has a $1M carbon storage public information sharing geologic database project underway. Public outreach partners include the University of Alaska Fairbanks Alaska Center for Energy and Power and Alaska Resource Education.
• The University of Alaksa Fairbanks Institute of Northern Engineering is leading an $11M Alaska Railbelt Carbon Capture and Sequestration (ARCCS) CarbonSAFE Phase II storage assessment with the Energy and Environmental Research Center and Advanced Resources International. ARCCS is evaluating CCS for a new -fired power plant and two existing natural gas power plants in Anchorage operated by Chugach Electric Association. For more information, visit the ARCCS project page.
• Arctic Slope Regional Corporation Energy Services (AES), Santos, and Repsol are carrying out a $3M Direct Air Capture Pre-Feasibility Study ongoing with the U.S. Department of Energy.
• AES and Santos were selected for award on a $62M CarbonSAFE Phase III project focusing on subsurface site characterization and permitting for a potential North Slope project site called North to the Future CCS Hub.

Additional Studies

• The U.S. Department of Energy and the Japan Ministry of Economy, Trade and Industry announced a cross-border CCS import to Alaska feasibility study, with Phase I focused on transportation feasibility.
• Hilcorp, Sumitomo, and K Line signed joint study agreement for CCS feasibility of imports from Japan to Alaska for sequestration.

What industries use carbon capture?

Carbon dioxide capture is being applied in manufacturing plants for cement, iron, steel, chemicals, and ethanol, in natural gas processing, oil refining, and power and heat generation. 

Does carbon capture actually work technically?

Yes, underground carbon dioxide (CO₂) injection first began more than 50 years ago in western Texas. By 2023, the world’s carbon capture and storage capacity reached 55 million tonnes per annum (MMTPA). In 2023 alone, 198 new carbon capture commercial facilities were added to the development pipeline, which would grow global CCS capacity to 361 MMTPA. Major investors are putting money on the line to design and build new CCS projects. Most of the new capacity is projected for emerging and developing countries. 

This U.S. Environmental Protection Agency site provides key information regarding the supply, uses, underground injection, and geologic sequestration of carbon dioxide in the United States.

In Alaska, carbon capture technology is used to process the entire produced gas stream in Prudhoe Bay since 1986. The Central Gas Facility separates carbon dioxide from the natural gas stream (12.5% CO₂) and manufactures miscible injection gas (20% CO₂) for enhanced oil recovery. The Prudhoe Miscible Gas Injection Project has increased field recovery by over 500 million barrels of oil. 

Is CCUS economically feasible?

Yes, it is feasible.

Like any business, there is a wide range of project costs for CCUS. Generally, capture costs are higher for carbon dioxide sources with lower concentration and lower pressure. Some projects are commercially viable today using existing technology and costs. Other projects may not strictly be economically attractive but may move forward if a business decides that carbon dioxide capture makes sense for other reasons.

Economics of projects may change over time with new technologies and applications. Carbon dioxide (CO₂) capture from ethanol manufacturing typically has a low cost, ~ $20/tonne CO₂, so they have been early adopters. Coal-fired plants capture costs have been estimated in the range of $50 to $65/tonne. At the federal level, 45Q tax credits for geologic sequestration are currently $85/tonne. They were introduced in 2008 at a lower rate per tonne and have been extended in length and increased in dollar amount since then.

Is CCUS legal?

Yes, the Alaska Legislature passed the Carbon Storage Bill, HB50, in April 2024. The Governor signed it into law July 2024. This creates a comprehensive framework for carbon dioxide (CO₂) storage in Alaska. In February 2025, regulations developed by the Alaska Department of Natural Resources (DNR) took effect for carbon storage. 

CO₂ injection, also known as Class VI injection, is currently regulated by the EPA. The Alaska Oil and Gas Conservation Commission (AOGCC) is pursuing Class VI injection well primacy from EPA, as authorized in May 2023 by SB48. 

The Governor, Legislature, and state agencies including DNR and AOGCC are actively working to enable carbon capture and storage in Alaska. 

Will carbon capture reduce the carbon dioxide in the air and kill all the plants or make them difficult to grow?

No.

Most facilities are installed at single point sources, for example at a power or ethanol plant. These capture carbon dioxide (CO2) rather than allowing it to be emitted into the air and further increase its concentration in the atmosphere. 

There are 860 billion tonnes (or gigatonnes, GT) of CO₂ in the atmosphere, at a concentration of around 420 parts per million. The planned CO₂ capture equipment capacity is thousands of times smaller than the CO₂ volume in the air. This equipment reduces future emissions but will not reduce the current air’s CO₂ concentration below favorable levels for plant growth.

Direct air capture, which removes CO₂ directly from the air, is not widely deployed commercially and still needs significant development. Direct air capture facilities that are operational do not impact local atmospheric conditions in a manner that impacts local plant growth. 

CCUS is expensive. Who is making you do it?

There is a 45Q tax credit, first made available in 2008, which has since been increased in dollar value to $85/tonne CO₂ sequestered and expanded to apply to more applications of carbon capture, use, and sequestration. It is currently available for projects that initiate onsite construction by December 31, 2032. This is one reason some may wish to do CCUS.

Carbon dioxide management also gives competitive advantages:

• Improves investments.
• Increases opportunities.
• Lowers carbon intensity of products.
• Creates marketable products and enhances customer brand loyalty  For example, many airlines are selling CO₂ emissions offsets that make people feel better about their traveling.
• Making a product that is carbon neutral makes it more sellable.
• Enables some investors in the free market to express a preference for, and fund, low carbon dioxide intensity energy and other products. 

Why is CCUS necessary?

To reduce carbon dioxide (CO₂₎ emissions, the Intergovernmental Panel on Climate Change has estimated the cost for clean energy security globally to more than double without carbon capture, use, and storage (CCUS).

Adding CCUS to existing plants is lower cost than total replacement.

In Alaska, installing CCUS may be necessary to attract new investments and to create options to decarbonize activities vital to the State’s economy including power generation, refineries, and oil and gas production. 

 

Carbon dioxide transportation

Is transportation of carbon dioxide in pipelines safe?

Pipeline transportation is safe, and it is far safer than other modes of transport, including trucking and rail.

Underground carbon dioxide (CO₂) injection first began more than 50 years ago in western Texas. Decades of data has helped us understand how CO₂ behaves and how to safely transport it through pipelines. Today, millions of metric tons of CO₂ are safely transported daily across the country through 5,000+ miles of pipelines. Before a CO₂ storage project ever begins, acceptable routes are identified and evaluated for the new pipelines.

Pipelines and storage sites have stringent regulations, monitoring, and mitigation requirements. Alaska prioritizes significant planning and research, training, and technology into all aspects of pipeline safety to be prepared for any unexpected scenarios. 

How are underground CO2 storage sites and pipelines monitored?

Multiple safeguards and protections are put in place for storage sites and pipelines. Safety is ensured through rigorous site selection, extensive monitoring, and regulatory oversight. Alaska requires extensive review and approval of plans to operate pipelines and storage facilities and inject carbon dioxide (CO₂₎. In addition, the U.S. Environmental Protection Agency requires a monitoring, reporting, and verification plan for sequestered CO₂.

Typical project requirements include:

• Class VI well construction with surface casing/ cementing protecting water resources; cementing from the surface to the injection point; and corrosion-resistant materials
• Next-Level Monitoring: multi-layer, multi-protection, multi-action 24/7/365
• Operational monitoring for temperature and pressure changes that could indicate early anomalies
• Leak detection and alerts
• Deep underground monitoring to ensure that the CO₂ remains securely in the storage zone
• Surface and near surface monitoring to ensure no environmental effects
• Surface water, groundwater and soil regular testing
• Automatic shutoff requirements
• Risk assessment and mitigation including comprehensive manuals at each site and control center with actions for various scenarios
• Post injection site care and closure, including continuous monitoring after injection ends, until it is demonstrated that the CO₂ stops moving (at least 10 years)
• Pipeline operators partner with local emergency managers to develop and review emergency response plans, and conduct regular trainings and drills
• Comprehensive financial burden on storage companies to cover the cost of any necessary corrective action, injection well plugging, site care or closure, and emergency or remedial response

Source: North Dakota Industrial Commission Understanding CO₂ Storage and Pipeline Safety

What happened with the 2020 pipeline failure in Satartia, Mississippi?

The 2020 carbon dioxide (CO₂) pipeline failure in Satartia, Mississippi resulted in several lessons learned.

First, the pipeline operator was cited for violating multiple regulations. When federal pipeline regulations are followed, pipelines outperform the safety standards of both rail and truck transit. Second, the unstable soil where the pipeline was installed was susceptible to movement from the preceding heavy rains (7.5 to 13.5 inches above average), resulting in a landslide that ruptured the pipeline as the ground shifted. Lastly, local weather conditions, lack of wind, and the density and volume of the CO₂ released slowed its dissipation; the pipeline operator models underestimated the potential affected area; the operator did not adequately inform local emergency responders; and the pipeline did not contain pure CO₂. 

CO₂ is non-flammable and non-explosive. The official term for what happened is called "explosive decompression" and happens when a pressurized container fails rapidly—like blowing up a balloon and popping it with a pin. The material escapes quickly, causing a powerful rush and noise, disturbing the ground immediately around the break point. In this case the pipe that carried the CO2 was suddenly broken by the landslide and released the pressurized gas very quickly.

 

What happens if a leak is detected?

Transportation systems are designed with leak detection, alerts, and shutoff equipment. Valves along the length of the pipeline are designed to shut down if a leak is detected, limiting the carbon dioxide (CO₂) volume released.

While prolonged exposure to high concentrations of CO₂ can cause breathing difficulty, the gas typically quickly evaporates into the air and requires little to no clean-up.

Local emergency responders play a crucial role in ensuring public safety near CO₂ pipelines. Even though a CO₂ pipeline leak is extremely rare, it is important that first responders have the information they need to prepare for and respond to all potential situations.

Pipeline operators are required to work closely with responders to develop and review emergency response plans and conduct regular training and drills.

Carbon dioxide geologic storage

What is the difference between storage and sequestration?

Storage and sequestration are used interchangeably in terms of CCS.

Sequestration means to isolate, per the Oxford English Dictionary. For CCS, sequestration means permanent carbon dioxide storage underground.

Storage is a simpler word.

What is “cap rock”?

Cap rock is low-permeability rock that does not allow gas and liquids to move through it. Carbon dioxide (CO2) is injected in a porous and permeable storage layer and held in place by cap rock, as shown in the figure below.

How deep does CO2 need to be injected?

Carbon dioxide (CO₂) is stored underground at depths where the pressure is high enough, so it is a liquid rather than a gas, typically 3000’ or deeper. 

Liquid CO₂ takes up a much smaller space—a hundred times smaller than as a gas.

What happens after carbon dioxide is injected underground?

When carbon dioxide (CO₂₎ is injected underground, it flows through the reservoir and interacts with the water and rocks it contacts. Some CO₂ dissolves into the water—like a soda—and is trapped in immobile reservoir water, some is trapped by capillary forces, and the remaining CO₂ is trapped by the cap rock. Depending on the reservoir rock minerals, CO₂ can also chemically convert into a carbonate rock.

How is injection controlled to avoid fracturing the cap rock?

The injection well and reservoir pressures are continuously monitored and managed throughout a project’s lifetime to ensure pressures are at or below the permitted level in the target injection reservoir(s) with a safety margin below the fracture pressure of the rock. 

How is CO2 plume movement predicted?

Geological and engineering models are used to predict the vertical and areal movement of carbon dioxide (CO₂) through the reservoir.

The example shown below is a model predicting the pressure and CO₂ saturations during injection into the reservoir. Note the highest pressures occur at the point of injection, i.e. where the well meets the rock, and reduces as the injected CO₂ moves through the reservoir and the pressure dissipates.

Source: Intera modeling for U.S. Department of Energy

What happens if an earthquake fractures the well casing seal?

The site is screened for geologic integrity and stability. There are oil and gas reservoirs nearby that have been there for millions of years and survived all kinds of earthquakes. We find geologically stable sites like those reservoirs and design wells to be strong enough to survive earthquakes, just like we design buildings to survive earthquakes.
There are hundreds of wells in the Cook Inlet and Kenai Peninsula and thousands on the North Slope. All experience earthquakes, and many wells are decades old. The Alaska oil and gas industry and the Alaska Oil and Gas Conservation Commission (AOGCC) have decades of experience designing wells with the threat of earthquakes in mind. Wells are designed with multiple barriers to prevent the migration of fluids and with materials proven to be effective in Alaska’s challenging environments.  

What happens if a leak is detected?

If leaks are detected, the cause is investigated, and corrective actions are taken to ensure the containment of injected carbon dioxide (CO₂₎. Corrective actions could include well repairs or changes to operating practices.

CO₂ storage sites can have subsurface pressure monitoring both in-zone and above the designated storage reservoir.