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 415ppm - Direct Air Capture
  • Biochemically converting CO2 in the air at 415 ppm with reforestation, afforestation, regenerative farming and soil management via photosynthesis

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" phys.org - May 20, 2020

Problems with Capturing CO2 from Air

Capturing carbon directly from the air is problematic because the concentration from a processing standpoint is so low, 415ppm. Natural biological processes, photosynthesis and trees may be a better way than trying to do it artificially.

Why carbon capture might be an illusion, see:

"The Carbon Capture (NETs) Big Lie, Carbon Capture Reduction Calculations Now Being Used to Set Global Fossil Fuel Reduction Targets Will Save Us From Extinction --- Just in Time" - JobOneForHumanity
"New carbon dioxide capture technology is not the magic bullet against climate change" - Phys.org - April 18, 2019
"Study Casts Doubt on Carbon Capture" - Phys.org - Taylor Kubota - October 25, 2019

Artificial Carbon Capture Technologies

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" - Phys.org - 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" - Phys.org - 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 phys.org, “New route to carbon-neutral fuels from carbon dioxide discovered”, Sept 16, 2019 at:

"New route to carbon-neutral fuels from carbon dioxide discovered" - Phys.org - 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" - Phys.org - 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

Natural Carbon Capture

(aka 'Negative Emissions')

Regenerative Agriculture

(aka Regenerative Farming, Regenerative Annual Cropping)

From Project Drawdown:

Regenerative agricultural practices include:

  • no tillage,
  • diverse cover crops,
  • in-farm fertility (no external nutrients),
  • no pesticides or synthetic fertilizers, and
  • multiple crop rotations.

Together, these practices increase carbon-rich soil organic matter. The result: vital microbes proliferate, roots go deeper, nutrient uptake improves, water retention increases, plants are more pest resistant, and soil fertility compounds. Farms are seeing soil carbon levels rise from a baseline of 1 to 2 percent up to 5 to 8 percent over ten or more years, which can add up to 25 to 60 tons of carbon per acre.

It is estimated that at least 50 percent of the carbon in the earth’s soils has been released into the atmosphere over the past centuries. Bringing that carbon back home through regenerative agriculture is one of the greatest opportunities to address human and climate health, along with the financial well-being of farmers.

Regenerative Agriculture is a system of farming including healthy soil principles and practices that increases biodiversity, enriches soils, improves watersheds, and enhances ecosystem services. Regenerative Agriculture aims to capture carbon in soil and aboveground biomass, reversing current global trends of atmospheric accumulation and loss of healthy soils. Irrigations demands are also improved with the improved water retention arising from improved soil quality.

"Regenerative Agriculture: Solid Principles, Extraordinary Claims" - Washington State University - April 4, 2018 - a discussion

A component of Regenerative Agriculture is the practice of composting. Dr. David C. Johnson, molecular biologist and research scientist at the New Mexico State University has developed a system that brings lifeless soils back to life by reintroducing beneficial microorganisms to the soil with biologically enhanced compost from a 'bioreactor'.

"Compost For Soil Regeneration - Johnson–Su Composting Bioreactor

Our 350 Santa Fe / XR Urban Farming Program has identified additional resources. See our Good News Archived Articles for more Regenerative Agriculture articles.

Healthy Soil Principles

An integral part of Regenerative Agriculture, healthy soil principles have been identified by farmers and scientists. While coming more from a farming perspective, these concepts apply similarly to rangelands, urban farming and victory gardens. The principles work in every ecosystem, on every scale, and foster a more holistic approach.

1. Keep soil covered

In nature, bare soil is an anomaly. Soil cover is critical to protect soil from wind and water erosion, provide food and habitat for macro- and microorganisms, and to prevent moisture evaporation and germination of weed seeds in farm fields. The best way to keep soil covered is to grow a dense and diverse carpet of plants or grasses, offering microbes both food and shelter. Protecting soil with a layer of mulch or litter holds in moisture, buffers soil temperature, cuts down on evaporation and makes the most out of New Mexico’s scarce water resources.

2. Minimize soil disturbance on cropland & minimize external inputs

Tilling, chemical fertilizers, herbicides and pesticides harm the web of life in the soil and should be avoided as much as possible. Alternatively, compost boosts soil health, promoting stronger plants and resilience towards disease, and supporting microbes that feed directly on parasites.

3. Maximize biodiversity

Greater diversity above and below the ground creates more resilient and productive working lands. Each plant, insect or animal has something different to offer and each of them plays a role in maintaining soil health. Together they provide a varied diet for soil microorganisms, with additional benefits such as breaking of disease cycles and creation of habitat for wildlife and pollinators. Nature does not know monocultures, instead diversity enhances ecosystem function.

4. Maintain living roots

Soil organisms cluster around roots, where they exchange nutrients with plants. Those living roots provide their basic food source: carbon. In turn, the soil biology fuels the plant nutrient cycle. Encouraging a variety of warm and cool season grasses through planned grazing, replacing annuals with perennials, or planting multi-species cover crops are some of the strategies to ensure continuous roots year-round.

5. Integrate animals

A healthy farm ecosystem provides habitat for animals large and small, including pollinators, earthworms, and all of the soil microbiology. Planned grazing, which mimics migratory herds of ungulates, is essential for soil health on rangeland: animals are moved quickly through pastures in one compact herd, giving grasses adequate time to recover in between grazing periods. Animals can also be used to graze cover crops or post harvest. Hedgerows or pollinator strips provide food and habitat for beneficial insects and earthworms thrive in healthy soil.

New Mexico has a number of agricultural examples on how to apply the Healthy Soil Principles.

Source: New Mexico Healthy Soil Working Group.

Bioenergy with carbon capture and storage

Bioenergy with carbon capture and storage – better known by the acronym “BECCS” – may be one of the more viable and cost-effective negative emissions technologies. There are many attractive features, since this technology could provide energy – thus reducing our need for fossil fuels – and remove CO2 from the atmosphere at the same time.

However, the full carbon-cycle impacts of large-scale deployment of BECCS are not well studied. No studies have looked at these impacts specifically for a scenario that could meet the 1.5°C target.

"Why BECCS might not produce ‘negative’ emissions after all" - Carbon Brief - Dr. Anna Harper - August 14, 2018

Reforestation and Afforestation

From Nature4Climate website...

Afforestation (growing new forests) and reforestation (restoring existing forests), combined with a variety of land management and conservation practices, could remove around 1-2bn tonnes of carbon from the atmosphere per year. There is a potential warming effect of forests as well, especially in high-latitude areas where adding trees can warm the climate since their albedo is lower than snowy ground or agricultural land.

Around the world, huge swaths of temperate and tropical forests have been cleared for human activity. Many of those lands are being used productively to grow food and raise livestock that we need and, with yet better practices, can sustainably yield even more food. Yet many other deforested lands are degraded, produce less than one cow per hectare, and are good candidates for reforestation.

"Reforestation" - Nature for Climate

Enhanced Rock Weathering

Still under development, some processes add minerals to the seas, others distribute dust on the land:

"Removal of atmospheric CO2 by rock weathering holds promise for mitigating climate change" - Nature - July 8, 2020
"Enhanced Weathering for Carbon Capture" - Earth.org - February 2020
"CO2 Removal With Enhanced Weathering and Ocean Alkalinity Enhancement: Potential Risks and Co-benefits for Marine Pelagic Ecosystems" - Frontiers in Climate - October 2019
"Enhanced Weathering" - The Azimuth Project - undated - includes some chemistry