Carbon Capture and Sequestration

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Different Types of Carbon Capture

There are several different approaches to carbon capture and sequestration:

  • Artificially converting CO2 in effluent gasses from industrial processes where concentrations are as much as 20%.
  • Artificially converting CO2 from the air at 420ppm or higher - Direct Air Capture
  • Biochemically converting CO2 in the air at 420 ppm or higher with reforestation, afforestation, regenerative farming and soil management via photosynthesis, see Land Based Solutions

A positive report from Imperial College, London speaks to the growth of carbon capture and storage, and its contribution to meeting the necessary goals. Storage projections in Gt are less than previously estimated if we act soon:

"World can likely capture and store enough carbon dioxide to meet climate targets" - May 20, 2020

Once carbon (as CO2) is captured, the question is what to do with it next. In addition to storing an enriched stream of CO2 there are some alternatives, such as methanation with green hydrogen in the Power-to-Gas process. Use of the gas to enhance oil and gas well production is decidedly not recommended since there are risks that the CO2 may return to the atmosphere in addition to the need to transition away from fossil fuels in the first place.

Carbon Capture and Sequestration Projects

CCS Effectiveness

Industry has made many claims of successful carbon capture from effluent streams of up to 95%. Most claims are based on the local carbon material balance and don't include losses from say well-head to customer. As reported in, Mark Z. Jacobson at Stanford University

"calculated all the emissions associated with [the coal] plants that could contribute to global warming, [and] converted them to the equivalent amount of carbon dioxide in order to compare his data with the standard estimate. He found that in both cases the equipment captured the equivalent of only 10-11 percent of the emissions they produced, averaged over 20 years."
"Even without accounting for upstream emissions, the equipment associated with the coal plant was only 55.4 percent efficient over 6 months, on average"

"Study Casts Doubt on Carbon Capture" - - Taylor Kubota - October 25, 2019

Petra Nova CCS Progress?

Reuters reported on September 2023:

Carbon capture project back at Texas coal plant after 3-year shutdown
"The Petra Nova CCS project, owned by a subsidiary of JX Nippon oil and Gas Exploration, aims to capture 1.4 million tonnes of carbon dioxide per year and is one of the world's largest CCUS projects.
Petra Nova began operating in 2016 at a coal-fired power plant in Texas and shut down less than four years later due to a plunge in oil prices during the COVID-19 pandemic. It restarted on Sept. 5, JX Nippon said this week."

Air Products Projects

Air Products explains their position and plans on Carbon Capture.

Canada Net-zero Hydrogen Energy Complex

Earlier reports from Air Products suggested the best Carbon Capture technology could perform was 40% recovery. A new Canadian project is planned for greater than 95% carbon capture in a net-zero hydrogen energy complex. The project will make hydrogen from natural gas (SMR), capture the CO2 and store it 'safely back' underground.

Port Arthur, Texas

Air Products reports (Feb 2024) it has a new facility operating within the Valero Refinery, Port Arthur, Texas where the captured CO2 from two Steam Methane Reformers is used for Enhanced Oil Recovery.

Louisiana New Facility

Air Products also plans to build a $4.5B blue hydrogen facility in Louisiana in which they expect to capture 5 million tonnes per year of CO2 while producing 750 MMSCFD of hydrogen. [Note the non-comparable units]. The inference is that all that CO2 will be sequestered permanently in Louisiana' geological strata.

By our calculations to make 750 MMSCFD of hydrogen (million standard cubic feet per day) requires 1,393,449.8 tonnes per year of methane at 100% conversion which in turn also produces 3,831,986.95 tonnes per year of CO2. The resulting CO2 recovery percentage comes to 130.48%. Which means either the 5 million tonnes/yr of CO2 captured is an over statement or efficiencies and losses in the manufacturing process are very significant and at a minimum are 27.5%.

The project is expected to be operational in 2026.


Density of Hydrogen at STP = 0.08988 g/L
1 cubic foot = 28.3168 liters
1 cubic meter = 1000 liters
1 tonne = 1,000,000 gm

Reaction Stoichiometry
CH4 + 2H2O → CO2 + 4H2
1 mole CH4 (MW 16) => 4 moles of H2 (MW 2) and 1 mole of CO2 (MW 44)

16 kg of CH4 converts to 8 kg H2
16 kg of CH4 converts to 44 kg CO2

750 MMSCFD H2 = 750 * 1,000,000 * 365 * 28.3168 * 0.08988 / 1,000,000 tonnes/yr H2 = 696,724.9 tonnes/yr H2.

which in turn requires : 696,724.9 * 16/8 = 1,393,449.8 tonnes/yr CH4.

and produces 1,393,449.8 * 44/16 = 3,831,986.95 tonnes/yr CO2.

with a percent recovery = 100 * 5,000,000 / 3,831,986.95 = 130.48 %!

Losses to make up the difference = 100 - 100/30.48 = 27.5%

Direct Carbon Capture

Natural Direct Air Capture

Natural biological processes, photosynthesis and trees may be a better way than trying to do it artificially. See Land Based Solutions

Artificial Direct Air Capture (DAC)

Direct Air Capture of carbon directly from the air is problematic because the concentration from a processing standpoint is so low, over 420ppm. Climeworks runs a facility in Iceland that demonstrates the possibility with captured carbon being injected in suitable basaltic rocks. However, once we stop adding giga-tonnes of CO2 into the atmosphere we would still need to lower the concentration back down to below 350 ppm from >420 ppm levels in 2023. Improvements in the technology are clearly needed.

Why carbon capture might be an illusion, see:

"The IPCC's Carbon Capture (NETs) Big Lie About the Existence of Magical Carbon Sucking Unicorns" - JobOneForHumanity
"New carbon dioxide capture technology is not the magic bullet against climate change" - - April 18, 2019
"Study Casts Doubt on Carbon Capture" - - Taylor Kubota - October 25, 2019
"The False Promise of Carbon Capture as a Climate Solution" - Scientific American - March 1, 2024

Artificial Direct Ocean Capture

Carbon dioxide released into the air becomes absorbed or dissolved by the ocean's waters. For every tonne of CO2 released 30-40% is 'sequestered' by salt water. For every tonne removed from the atmosphere 30-40% will come from seawater to maintain chemical equilibrium. Sea water A new method for removing the greenhouse gas from the ocean could be far more efficient than existing systems for removing it from the air, according to a report from MIT News, because the concentration of carbon dioxide in seawater is more than 100 times greater than it is in air. Note that this process generates a carbon dioxide stream that still has to be stored in some manner.

How to pull carbon dioxide out of seawater February 16, 2023

For more information on how CO2 moves between the atmosphere and the oceans this is an excellent resource:

Carbon Dioxide in the Ocean and Atmosphere - Water Encyclopedia

CO2 Storage

Geologic Sequestration of Carbon Dioxide in Class VI Wells

Per the EPA website "Class VI - Wells used for Geologic Sequestration (GS) of Carbon Dioxide", "Geologic Sequestration is the process of injecting carbon dioxide, captured from an industrial (e.g., steel and cement production) or energy-related source (e.g., a power plant or natural gas processing facility), into deep subsurface rock formations for long-term storage. This is part of a process frequently referred to as “carbon capture and storage” or CCS.

"Underground injection of CO2 for purposes such as Enhanced Oil Recovery (EOR) and enhanced gas recovery (EGR) is a long-standing practice. CO2 injection specifically for GS involves different technical issues and potentially much larger volumes of CO2 and larger scale projects than in the past.

"Class VI wells are used to inject carbon dioxide (CO2) into deep rock formations. This long-term underground storage is called geologic sequestration (GS). Geologic sequestration refers to technologies to reduce CO2 emissions to the atmosphere and mitigate climate change.

For more discussion on Class VI Wells see:

EPA’s Class VI Well Program Key to Deploying CO2 Geologic Storage - Great Plains Institute - Feb 2022

We believe Class VI wells allow storage of CO2 in salt domes and other 'saline formations' and excludes the use of wells to chemically lock CO2 as described in the next section.

Geological Sequestration

Geological Sequestration, sometimes known as Carbon Mineral Sequestration, is the step after 'carbon capture' where CO2 has been separated or concentrated from a waste stream and is pumped underground into suitable geological strata that stores the gas or a solution of the CO2 gas by reacting it with minerals to form solid carbonates.

For details on water usage as part of the process for carbon capture and sequestration, especially in deep injection wells, there is a wealth of information in a report published by the National Institute of Health library:

"Water Challenges for Geologic Carbon Capture and Sequestration" - NREL/LLNL - February 2010

As reported by BBC Future Planet at:

How Iceland is undoing carbon emissions for good - BBC - July 16, 2020

At aluminium smelters, CO2 is normally released to the atmosphere. At the smelter in Iceland, CO2 is captured, dissolved in water and injected into the black basalt rock that the volcanic island is famous for. CO2 dissolved in water prior to or during injection into the porous basalt rock reacts with the rock formations at a depth of about 500m, where it can turn rapidly into minerals. At Hellisheiði, it takes about two years for 95% of the CO2 to be mineralised. The process can take more or less time at other sites, depending on a few factors. One is the depth at which the carbon is injected, and another is the temperature of the rock formation – the rate of the mineralisation process is generally faster at higher temperatures.

Carbon Dioxide Underground Storage

Physical Storage

In conventional carbon capture and storage, recovered CO2 can be injected at high pressure into sedimentary basins in a gaseous, liquid or supercritical phase (where the liquid is at a temperature and pressure beyond the point it usually turns into a gas). An impermeable cap rock ordinarily prevents the CO2 from leaking back to the surface though many see this as a major risk.

See Enhanced Oil Recovery

Chemical and Permanent Storage

Climeworks runs a facility in Iceland that demonstrates the possibility with Direct Air Capture carbon being injected in suitable basaltic rocks. Over time, perhaps around two years the water-CO2 solution reacts with the rock to make solid calcium carbonate. Scaling up this pilot plant level test would require an enormous investment.

CO2 Capture

Solar Thermal Electrochemical Photo Process

Perhaps there’s hope yet with the Solar Thermal Electrochemical Photo (STEP) carbon capture Process (George Washington University, 2010):

"Solar-powered process could decrease carbon dioxide to pre-industrial levels in 10 years" - - Lisa Zyga - July 22, 2010

Similarly for CO2 to Carbon Nanotubes emerging technology (George Washington University, 2015) see:

"Carbon Capture & Solar Research" - Licht Research Group

and see:

"‘Diamonds from the sky’ approach turns CO2 into valuable products" ACS - August 19, 2015

Metal Oxide Frameworks

Metal Oxide Frameworks (MOF) can reportedly capture CO2 directly, see:

"Metal–Organic Framework-Based Materials for Energy Conversion and Storage" - ACS - Tianjie Qiu - January 8, 2020.
"New breakthrough in nanotechnology that uses atmospheric carbon to make useful chemicals" - - Matt Cichowicz - October 3, 2018

The process requires a source of hydrogen gas. There remain lots of questions since this is still an area of research. Some progress from 2020:

"New technique to capture carbon dioxide could greatly reduce power plant greenhouse gases" - Phys org - Univ. Berkley - July 23, 2020

Cerium Catalyst Conversion to CO

An electrolysis process using a cerium oxide electrode selectively produces CO without the inconvenience of solid carbon. From, “New route to carbon-neutral fuels from carbon dioxide discovered”, Sept 16, 2019 at:

"New route to carbon-neutral fuels from carbon dioxide discovered" - - Stanford University - September 16, 2019

Electrochemical Processes

The technique, based on passing air through a stack of charged electrochemical plates, is described in a new paper in the journal Energy and Environmental Science, by MIT postdoc Sahag Voskian, who developed the work during his PhD, and T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering and reported at:

"MIT engineers develop a new way to remove carbon dioxide from air" - MIT News - David Chandler - October 24, 2019

For a PBSNewshour discussion on the technology see:

"This new ‘battery’ aims to spark a carbon capture revolution" - PBS Newshour - Nsikan Akpan - November 15, 2019

While the process (still in the lab) removes CO2 from the air and can provide a pure stream of CO2, that CO2 has to be stored and disposed of.

Zeolite Processes

A “new material is a bio-based hybrid foam infused with a high amount of CO2-adsorbing 'zeolites," microporous aluminosilicates. This material has been shown to have very promising properties. The porous, open structure of the material gives it a great ability to adsorb the carbon dioxide” from:

"A sustainable new material for carbon dioxide capture" - - Chalmers University of Technology - December 9, 2019

Polymer Membrane Processes

A polymer membrane that enhances the separation of CO2 in effluent gases is described in:

"A Surprising Substance May Be Key in Capturing CO2 in the Atmosphere" - Norewegian University of Science and Technology - December 11, 2019

Artificial Photosynthesis

Researchers have developed a standalone device that converts sunlight, carbon dioxide, and water into a "carbon-neutral fuel", actually formic acid, without requiring any additional components or electricity. Formic acid is an organic molecule that can be used as a raw material for other organic compounds. It might have the advantage of backing our fossil-fuel based formic acid production. Formic acid in itself is a useful product as a preservative in agriculture. [Note as reported "converted to hydrogen" is not chemically possible.]

"Artificial Photosynthesis Advance: Standalone Device Converts Sunlight, CO2 and Water Into Clean Fuel" - ScienceTechDaily - August 24, 2020