Back to Basics, Energy, Sustainability

Back to Basics: Carbon Capture, Storage, and Repurposing

Back to Basics is a weekly feature that highlights important but possibly overlooked information that any EHS professional should know. This week, we examine carbon capture, storage, and reporting.

There has been a shift in attitude toward climate action. Instead of being viewed as a source of job loss, climate action is seen as a vast new field for job growth, economic opportunity, and technological advances.

The week of September 13, 2022, marked the opening of the United Nation’s 77th General Assembly (UNGA 77) in New York City, where U.S. delegates were expected to announce that America is on track to cut greenhouse gas (GHG) emissions in half by 2030 and achieve net-zero emissions by 2050.

When it comes to reducing GHG emissions, the expansion of carbon capture and storage (CCS) is the next logical step.

What is CCS?

CCS is capturing carbon dioxide (CO2) at emissions sources or directly or indirectly from the atmosphere, then transporting it and storing it safely, which typically means in deep, underground locations.

When utilizing fossil fuels at powers plants, there are three techniques employed to capture, or “scrub,” CO2:

  • Pre-combustion traps CO2 in a process whereby fossil fuels are pre-burned in “gasifier” units to form synthetic gas. The exhaust stream from this process allows for CO2 capture and produces hydrogen, which is used in power production, fertilizer, and chemical gas fuel. This method is less costly than the post-combustion process, but the technology cannot be retrofitted in older power plants.
  • Post-combustion captures CO2 from the exhaust gases, and the process can be retrofitted to older power plants. It is the most commonly applied technology and is also used in other industrial applications utilizing fossil fuels.
  • Oxyfuel combustion utilizes a process that burns fossil fuels in oxygen rather than air. This means the flue gases produced are almost entirely CO2 and water vapor, which condense when cooled and create an almost pure CO2 that can be captured and stored. Plants using this process are sometimes called zero-emission plants because almost all of the CO2 is captured. The downside is that the process is highly energy-intensive, and there is a possibility that some CO2 dissolves into the remaining condensed water, which can require additional treatment.

Direct air capture (DAC) of CO2 is technology that’s still in its infancy. One company leading the way toward this new technology is Zurich, Switzerland-based Climeworks AG. Climeworks utilizes a three-step process for DAC:

  1. Air is drawn in through a fan located inside the collector. Once sucked in, it passes through a filter located inside the collector, which traps the CO2 particles.
  2. When the filter is completely full of CO2, the collector closes, and the temperature is raised to about 212 degrees Fahrenheit.
  3. Once the temperature rises, the filter releases the CO2 so it can be collected.

Climeworks partners with carbon storage companies so the CO2 is pumped directly from the filters to deep underground storage. The company claims 1 plant “does the work of 200,000 trees in 1,000 times less space.”

Safe CO2 storage

The main two methods for storing CO2 are deep geological storage and mineral storage.

Deep geological storage. This technique, also known as “geo-sequestration,” converts CO2 into a semiliquid, runny form that is known as “supercritical CO2.” The supercritical CO2 is injected into sedimentary rocks that offer porous spaces filled with salty water.  Physical structures such as caprocks and geochemical trapping devices are put in place to prevent the CO2 from escaping back into the atmosphere.

Enhanced oil recovery (EOR). This method has been used for many years in the United States for EOR. Injecting the supercritical CO2 increases oil production. It’s an attractive option for CO2 storage because the costs are offset by the sale of the additional recovered oil. However, burning those additional fossil fuels when used puts more CO2 into the atmosphere, which creates a viscous cycle that does little to reduce overall emissions.

Coal. Unmineable coal seams are considered too deep or too difficult to mine. These offer safe CO2 storage options, provided the coal is porous enough to absorb the CO2. During the process used for this storage method, the coal releases methane (CH4), called enhanced coal-bed methane (ECBM), which can be captured and sold. Just as in the EOR method, the subsequent burning of the CH4 as it is used creates additional emissions that offset the benefits of utilizing coal seams to store CO2.

Saline aquifers. Saline aquifers offer an additional CO2 storage option. These are deep rock formations containing high concentrations of salt water. There are many saline aquifers under the Gulf Coast, the North Sea, and mainland Europe.  Due to the abundance of saline aquifers, it is an attractive CO2 storage option, but it’s still a relatively new method.

“However, current research shows that several trapping mechanisms immobilize the CO2 underground, reducing the risk of leakage,” reports the British Geological Survey (BGS). “Unlike storage in oil fields or coal beds, there is no useful byproduct to offset the cost of storage.”

Mineral storage

Mineral storage happens when CO2 is reacted with minerals containing calcium, magnesium, or iron. The process is known as “mineral carbonation,” and it happens naturally over time in rock formation. These minerals are plentiful and stable, meaning there is no re-release of CO2 into the atmosphere. The problem is that this is a very slow, naturally occurring event. Speeding up the process requires a great deal of energy—60%–180% more energy for power plants utilizing CCS mineral storage as opposed to power plants that do not utilize CCS, according to the Intergovernmental Panel on Climate Change (IPCC), as reported by the BGS.

Regulating CCS

Governments worldwide are still determining the best regulatory frameworks for CCS. According to the BGS, the elements that must be considered include:

  • Systems to document the amount and type of CO2 being placed in underground storage
  • Monitoring the stability of CO2 stored underground
  • Early warning systems to detect potential problems
  • Assurance of the integrity of long-term storage methods
  • Systems to measure for leakage

“In Europe, an EC Directive says that the issues of leakage and potential long-term stewardship of storage sites must be addressed if the potential for [CCS] to provide substantial reductions in atmospheric CO2 emissions is to be realized,” continues the BGS.

Within the United States, certain states such as California have enacted regulations that will make those storing CO2 liable for any leakage for 100 years, says Upstream. This will make it extremely difficult for these companies to secure reasonable insurance coverage.

The Lone Star State

Texas regulators have made progress toward making the Lone Star State a prime area for CO2 storage.

“Texas is the largest producer of greenhouse gases in the United States, accounting for over one-eighth of all U.S. emissions,” says an article in Forbes. “Interestingly, Texas also has the largest potential for carbon storage in its vast underground formations, should geological carbon sequestration at scale becomes a reality. The U.S. Department of Energy has estimated that Texas has onshore storage capacity for between 661 million and 2.4 billion tons of carbon dioxide.”

Texas also owns more offshore land than other coastal states due to a law that went into effect when Texas was a sovereign nation, providing the Lone Star State with ownership of lands 10.35 miles offshore as compared with the usual 3.45 miles of ownership by other states.

In May, the Texas Railroad Commission (RRC) took an important step in its application to receive sole authority from the EPA to permit new carbon capture storage wells, known as Class IV injection wells. And in June, Texas Governor Greg Abbot signed a law giving the RRC the same regulatory authority over CO2 wells as it currently has over oil and gas wells.

“The [RRC] said, as part of its application to the U.S. [EPA], it will make proposed amendments to the agency’s carbon dioxide rule available for public comment,” reports the Houston Chronicle. “If the RRC is granted what’s called primacy by the EPA, it would mean operators only need to apply to the Commission for permits instead of to both agencies. The RRC says this will speed up the process, which sometimes takes years.”

To date, North Dakota and Wyoming are the only states to have received primacy enforcement authority from the EPA, according to Reuters.

The EPA primacy process has four stages:

  1. Pre-application
  2. Completeness review and determination
  3. Application evaluation
  4. Final rulemaking and codification

Texas is working closely with the EPA to complete the pre-application phase before submitting the state’s formal application.

“Until the RRC obtains primacy over the Class VI permitting process, projects that intend to permanently sequester carbon in Texas for incentives such as 45Q tax credits must seek authorization under both the RRC’s Chapter 5 rules and under the EPA’s Class VI program,” advises law firm Locke Lord LLP. “In anticipation of primacy, the RRC has coordinated with the EPA to share data from the EPA’s electronic permitting tool, the Geological Sequestration Data Tool (GSD), to ensure that the application review for both agencies is performed in parallel. This coordination streamlines the process for applicants and will facilitate the transfer to RRC primacy. As such, carbon sequestration project developers should not delay the often-lengthy process of permitting in anticipation of the primacy approval, as the process and required data will not change significantly upon approval.”

Repurposing CO2

Considering all the costs and regulatory challenges in storing CO2, many companies are coming up with other uses for this GHG.

Vodka, jet fuel, diamonds, activewear, eyeglass lenses, protein, concrete, plastic, foam, perfume, hand sanitizer, and shoes are some of the products being created from CO2.

The trademarked CleanCloud process captures CO2 before it escapes into the atmosphere, then puts it through a fermenting process (similar to traditional brewing techniques) whereby it transforms into liquid ethanol. Next, it is dehydrated to form ethylene and polymerized into EVA, a versatile and lightweight material that is used to produce performance foam for shoes.

Twelve, a California-based company, utilizes an electrolyzer that turns CO2 into syngas (synthesis gas), a mix of CO2 and hydrogen, that can be made into a variety of products. The process uses only renewable electricity and water, with oxygen being the only byproduct produced.

“Many aviation analysts agree that sustainable aviation fuel (SAF) will play a key role in reducing emissions from long-haul flights and larger aircraft. Batteries and hydrogen, meanwhile, are expected to power mainly short-haul and regional flights. Airlines currently use minuscule amounts of [SAF]: about 26 million gallons in 2021, or well below one percent of total jet fuel demand,” reports Canary Media. “The Biden administration aims to increase U.S. production of SAFs to 3 billion gallons per year by 2030 — an effort that recently received an important funding boost under the Inflation Reduction Act.”

The next hurdle for this growing industry is reaching mass production scalability, as the processes have been primarily utilized in small batches to date.  Additionally, the process used to turn CO2 into liquid is very energy-intensive, so it is important that the industry utilize sustainable energy sources for production so the amount of CO2 captured and repurposed exceeds the amount of emissions generated.

The benefits of change

“The only constant is change.” This saying is attributed to Heraclitus, a Greek philosopher who lived in 535 B.C.–475 B.C.

Throughout history, people have always resisted change. Examples include:

  • The Americans have need of the telephone, but we do not. We have plenty of messenger boys.”—Sir William Preece, Chief Engineer, British Post Office, 1876
  • “Television won’t be able to hold on to any market it captures after the first six months. People will soon get tired of staring at a plywood box every night.”—Darryl Zanuck, executive at 20th Century Fox, 1946
  • “There’s no chance that the iPhone is going to get any significant market share.”—Steve Ballmer, Microsoft CEO, 2007

Even the Internet was thought to be a passing fad with no reasonable manner to organize so much information.

Change generally leads to progress. Not only are net-zero emissions possible, but the environment will also greatly benefit from cleaner technology and energy sources.  

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