Carbon Capture Technologies

Carbon capture can refer to a number of different technologies. The most common technical term used today is carbon capture and storage (CCS), or CCS can also refer to "carbon capture and sequestration". CCS can be integrated into emissions-intensive industries, particularly fossil fuel power plants.

CCS often works to capture carbon dioxide emissions so that CO2 emissions can be transported to a storage site deep underground. Alternatively, CCS can sequester CO2 for use in industrial processes. So, in addition to capturing CO2 for storage - sequestering CO2 can also result in carbon capture and utilization, or CCU + storage/ sequestration.

Carbon capture utilization and storage/ sequestration (CCUS) implies that the captured carbon is used for a productive purpose. The captured CO2 can be stored, or it can be utilized. Captured CO2 is commonly used for enhanced oil recovery, or other industrial/ commercial uses (see more details about this below). Carbon capture technologies can also be used to enhance the production of hydrogen or synthetic gases/fuels. 

In pre-combustion carbon capture, fuel sources are gasified and the carbon is captured. CO2 is captured before any combustion. Post-combustion carbon capture separates carbon dioxide from emissions produced by fossil fuel combustion. Post-combustion CCS is primarily used in power plants, and pre-combustion CCS is primarily used in other industrial processes.

"Industrial processes where large-scale carbon capture has been demonstrated and is in commercial operation include coal gasification, ethanol production, fertilizer production, natural gas processing, refinery hydrogen production and, most recently, coal-fired power generation."  [quote from  -  c2es.org/carbon-capture]

"CCS is applicable beyond the energy sectors and can be applied to industrial sources of emissions, such as iron, steel, and concrete, which have limited abatement options."  [quote from  -  ccsknowledge.com/what-is-ccs/industry]

Ultimately, CCS can reduce CO2 emissions by 90% or more from fossil fuel-intensive industries, whether the CO2 is used for industry or stored deep underground. In practice, CCS is an important measure to reduce global CO2 emissions.

Removing carbon dioxide directly from the atmosphere is made possible by direct air capture (DAC), yet another carbon capture technology.

CCS can also be used with bioenergy. Bioenergy carbon capture and sequestration (BECCS) results in carbon-neutral, or even carbon negative, burning of biomass for energy; as the biomass is theoretically made carbon-free by the process of CCS.

DAC and BECCS are emerging carbon capture technologies, and represent exciting potential future uses of carbon capture. DAC and BECCS are potentially important future climate change mitigation technological pathways to help the world reach carbon neutrality.

BECCS is a technology that is still in various stages of R&D. BECCS can theoretically produce carbon-neutral emissions (theoretically it must be said because there is no large-scale BECCS plant commercially operational globally yet). With BECCS, there is a carbon-neutral cycle. carbon is sequestered from the atmosphere in the biomass, used to create energy, and the resulting carbon from the biomass energy production is again captured in the CCS process.

DAC is accomplished by sequestering carbon dioxide directly out of the air. DAC is being tested in demonstration phases and is not a large-scale commercially available technology yet (although on a small scale, DAC projects are operating in a few demonstration projects globally). DAC sequesters carbon from the air similar to how trees sequester carbon.

Carbon-intensive industries that should consider investing in and using carbon capture technology include fossil fuel power plants & oil/ gas refineries,  industries and companies such as fossil fuel-intensive product manufacturing companies, and cement and steel manufacturing companies.

This article will mostly focus on the term referring to the original technology, used to burn fossil fuels cleaner; CCS – carbon capture and storage/ sequestration.

Integrated Gasification Combined Cycle (IGCC) is a different technology from CCS that can also be implemented to burn fossil fuels cleaner.

Carbon Capture and Storage (CCS)

Conversations focusing on implementing sustainable technologies to fight anthropogenic climate change and reach net zero focus heavily on renewable energy sources. Solar and wind energy, and clean energy solutions like energy storage, electrifying HVAC systems, and electrifying vehicles, dominate the priority list of climate solutions.

However, there are other options available that work by upgrading current fossil fuel energy generation systems to harness the power of fossil fuels without heavy carbon dioxide emissions; such as CCS.

One means of utilizing existing fossil fuel infrastructure in a less carbon-intensive manner is the process of CCS. CCS turns dirty fossil fuel sources into cleaner energy sources. CCS is a simple, albeit costly, technology. CCS helps fight climate change by vastly reducing greenhouse gas emissions (GHGs) from energy generation. 

The process of CCS begins with the "capture" of CO2 from fossil fuel power plants (or potentially any GHG emissions-intensive energy generation plant).

The next steps involve compressing the CO2 gas, transporting it; and ultimately injecting the CO2 deep into the earth, or sequestering the CO2 for industrial use, where it also won't enter the planet's atmosphere.

Methods vary for the "capture" phase of CCS, although CO2 is often captured post-combustion.

Although CCS can be used with any energy generation process that produces CO2 emissions (including coal), it has been demonstrated often with natural gas combined cycle. 

The CO2 captured in CCS can be transported to a CO2 storage site, and then injected through a pipeline to a subterranean geological formation, several thousand feet below the surface.  In cases where pipelines are impossible, CO2 can also be transported to a storage site via ship. Pipelines can be established under the ocean, as well as in subterranean caverns on land.

CO2 captured in the CCS process can also be used for various industrial purposes and the production of various manufactured goods, instead of shipped to a storage location.

Carbon dioxide can be transported to industries for use with mass-produced goods like soda, or for use in oil development in a process known as enhanced oil recovery. These uses for CCS are commonly referred to as carbon capture utilization and storage (CCUS). There are a wide variety of potential uses for the CO2 captured in the CCS process.  

[NOTE: these statistics below are as of October 2019 and should be compared with the quote below, from a year later, to see the year-on-year growth of CCS globally] >>> Worldwide, there are about 19 large-scale CCS power plants in operation (a total of 51 CCS plants globally – 19 in operation...and 32 in various stages of development). Although the high cost of CCS keeps this technology from taking off worldwide, there are attempts being made to remove the barriers of high cost from the progress of CCS. With continued research and development, the cost of CCS is steadily dropping, making this technology more likely to have a larger market share in the future.

[NOTE: this quote is from December 2020 - you can see the growth (albeit the slow growth) of CCS globally]>>> "The global pipeline of CCS facilities has grown for three years in a row, with capture and storage capacity nearly doubling within three years and increasing 33% since 2019. A total of 65 commercial CCS facilities are in various stages of development globally. Twenty-six CCS facilities are in operation and are capturing 40 million tonnes of carbon dioxide annually."  [quote from  -  spglobal.com/marketintelligence/s/carbon-capture-and-storage-projects-on-the-rise-globally]

Integrated Gasification Combined Cycle (IGCC)

IGCC can turn the production and use of coal and gas into a cleaner operation. Although the term “clean coal” is often met with a snicker, IGCC technology is a promising means of making the idea of coal a less emissions-intensive reality (especially when also combined with CCS technologies).

Essentially, IGCC technologies turn coal into a gas form, or turn natural gas into a "cleaner", less emissions-intensive gas. IGCC technologies make it possible to remove all impurities, or “filter” fossil fuels, including extracting sulfur and mercury.

The gasification and cleansing process produces steam, which in turn fuels the overall operation of the fossil fuel power plant, including the gasification and cleansing process itself. The cleaner gas is then sent to a combustion turbine generator to create electricity.

IGCC technologies incorporate several ideas into one complex cycle; constantly feeding the power plant with the IGCC technologies without heavy carbon dioxide emissions. IGCC does this without pumping other GHGs and pollution, like sulfur and mercury into the atmosphere.

(For an example of a case study of IGCC with CCS, please see the link from the European Commission below).

As with CCS, the high costs of IGCC technologies are holding it back from large-scale development; and, as a result, there are only a limited number of commercial-scale IGCC plants globally.

IGCC technologies can be used with coal or with natural gas. IGCC with natural gas, especially combined cycle gas turbines (CCGT); and also ideally used with CCS operating in the CCGT power plants - is a hopeful, promising future mix of technologies that theoretically could produce low carbon natural gas (nearly GHG emissions-free) to power the grid. As of today, there are only a handful of such technologies in development stages in demonstration projects globally; and only a small handful of these types of low-carbon gas plants operating at a commercial scale anywhere worldwide.

CCS and IGCC are two viable options for combating global warming and creating "clean" (or more accurately - "cleaner") fossil fuel power plants. Despite the initial upfront costs of CCS and IGCC, current power plants utilizing these methods report high levels of success and dropping costs over the lifetime of the operation; these positives are in addition to the environmental benefits of removing CO2 from the atmosphere.

Additionally, the CO2 captured with CCS can be used productively, instead of simply stored underground. Again, productive uses for the CO2 sequestered from the CCS process include enhanced oil recovery, and use with manufactured products; and both CCS and IGCC technologies demonstrate promise in the enhancement of alternative fuels, such as hydrogen and SNG.

Following is a snippet from a PDF on the pros and cons of CCS technologies; from the European Commission. Among the benefits listed are the human and planetary health benefits of CCS technologies; such as the reduction of GHG emissions from energy generation, and resulting ecological and public health benefits. Among the cons of CCS is that implementing CCS technologies for fossil fuels, and even for bioenergy sources, still results in the depletion of natural resources.

"CCS has health and ecosystem benefits, but depletes natural resources

CCS is seen as a greener way to operate power stations, whilst ensuring an energy supply, allowing society time to make the transition to a low-carbon future. Nevertheless, energy is required to drive the CCS technology...

This study used life cycle impact assessment modelling...from three systems of power stations fitted with CCS technology: a pulverised coal (PC) combustion plant; a natural gas combined cycle (NGCC) power plant with post-combustion CO2 capture, and a coal-based integrated gasification combined cycle (IGCC) power plant with pre-combustion CO2 capture. The captured CO2 was assumed to be transported 300 km by pipeline and
injected into a storage site beneath the seafloor.

The study suggests that CCS produces climate change benefits as a result of reduced CO2 emissions. These benefits significantly reduce climate-related damage to human health, by 74% for PC, 78% for IGCC, and 68% for NGCC power plants with CCS, compared with conventional power plants without CCS."  [quote from  -  ec.europa.eu/environment/newsalert/pdf]

Please also see: Gasification - Creation of Syngas from Fossil Fuels and Low Carbon Sources such as Biogas