Direct Air Capture & Sequestration

     The diagram above shows, based on the laws of thermodynamics, the minimum energy to remove CO2 from ambient air (Direct air capture).  Removal requires about 3 times as much energy as the energy gained by burning coal and more than twice as much as from burning natural gas.  That is primarily because the CO2 is so dilute in the atmosphere.  For net CO2 removal with DAC, cheap energy (solar and wind, perhaps also small modular nuclear) is needed.

     However, the diagram above assumes energy use for fans to speed up air circulation across a catalyst that captures CO2 (there are many possible catalysts.)  Is also assumes that heat is later used to separate the CO2 from the catalyst, so that the capture process can begin anew and so that the purified CO2 can be pumped to its final resting place (or another use).

     Moreover, it concentrates on heat-based approaches.  Other approaches - including electric charge, pH change, humidity, and phase change - are gaining traction in the 2020s.  See diagram a little further down the page.  These approaches are generally less energy intensive.

Air Capture


How New ‘World’s Largest’ Vacuum to Suck CO2 from the Air Works 0524

Amazon Bets Big on Oil Giant Occidental’s Carbon Removal Project 0923

How an Oil Giant Took Control of Biden's Billion-Dollar Bet on Carbon Capture 0823

Can Vacuums Slow Global Warming? Administration Bets $1.2 Billion on It. 0823 - Much more progress on capture from high-density CO2 streams (100% at ethanol plants, ~15% at industrial plants, than 0.042% in ordinary air.

What’s Needed to Reach Net-Zero This Century - IEA 0423

Carbon-Sucking Tech Could Need More Energy than All Homes Use 0323

How to Suck Up CO2, Turn It into Baking Soda, and Store It in the Oceans 0323

Artificial Trees 0223

Carbon Removal Is Where Green Investment Should Go 0123

Competition Heats Up for U.S. Direct Air Capture Program 0123

CO2 Removal Efforts Seen Far behind What Is Needed 0123

New York Landlords Try Carbon-Sucking Towers to Comply with Climate Law 0123

Nasdaq Targets Boom in Market for Carbon Removal in Coming Years 1022

Why the $100 per Ton Target for Carbon Removal May Be ‘Pure Fantasy' 1022

Audi and Krajete Filter CO2 Out of the Air 1022

3 Big Direct Carbon Capture Deals to Know 1022

New Law Helps U.S. Firm Launch Wyoming Direct Air Carbon Capture Project 0922

Climeworks Predicts CO2 Removal Cost Drop to Below $250 / Tonne by 2030 - 0722

New Law Helps U.S. Firm Launch Wyoming Direct Air Carbon Capture Project 0922

The Chips Act Has a CO2 Removal Easter Egg 0822 - $1 billion for carbon removal research

Startup That Sucks CO2 from the Air Is Building a Big Plant in Iceland 0622

Can Carbon Capture Be Part of the Climate Solution? 0622

Carbon-Removal Industry Draws Billions to Fight Climate Change 0622

U.S. Steel Backs Snatching CO2 from the Air and Storing It in Concrete 0622

FaStartup That Sucks CO2 from the Air Is Building a Big Plant in Iceland 0622

Can Carbon Capture Be Part of the Climate Solution? 0622

Carbon-Removal Industry Draws Billions to Fight Climate Change 0622

U.S. Steel Backs Snatching CO2 from the Air and Storing It in Concrete 0622

Fastest CO2 Catcher Heralds New Age for Direct Air Capture 0522

Musk and Google Add to $2 Billion Boost for Carbon Removal 0522

Microsoft, Salesforce Add $300 Million to Carbon Removal’s Growing Cash Pile 0522

Whitehouse, Coons Introduce Act to Accelerate CO2 Removal 0522

Tonko, Peters Introduce CO2 Removal Legislation 0422

There Has Never Been a Better Time to Start a Carbon Removal Company 0422

Direct Air Capture 0422 - overview of DAC methods, EF.  Heirloom is projected to hit $50 / ton for carbon removal by 2035.  It gets rid of the other ~1/2 of energy use: moving air past the catalyst.  Use natural air circulation (slower) instead of fans.

Climeworks Raises $650 Million in Largest Round for Carbon Removal Startup 0422

A Scalable Direct Air Capture Process Based on Weathering Calcium Hydroxide 0322 - Heirloom explains its process.  Several pages, with chemical equations.

Carbon-Capture Startup Using Dirt Cheap Material Raises $53 Million 0322 - Limestone to calcium oxide and back


The Dream of Carbon Air Capture Edges Toward Reality 0821 - Movement has begun from $500-600 per ton of CO2 removed to $94-232.  Discussion of the industry.

Click for more

Fuel Cells and Game-Changing Tech to Remove 99% of CO2 from Air 0222

Bill Gates Invests in Carbon Capture Startup After Tech Breakthrough 0222

The Market & Policy Landscape for Advancing Direct Air Capture – Who Pays? 0122

As Carbon Emissions Rise Unabated, Scientists Eye a Methane Removal Fix 1121

“Urban Sequoia” Technology Could Turn Buildings into Climate-Fighting Tools 1121 - Stack or chimney effect draws air 

To Slow Global Warming, Some Researchers Want to Pull Methane Out of the Air 1121


These ‘Super-Trees’ Are Engineered to Capture More Carbon 0621

Direct Air Capture of CO2 Is Suddenly a Carbon Offset Option 0321

Microsoft Climate Fund Backs Climeworks Effort to Suck Up Carbon 0121

Chevron Invests in Carbon Capture and Utilization Startup Blue Planet 0121 - store CO2 in calcium carbonate aggregate for concrete

OpenAir’s R&D Roundup – Violet and Cyan Home CO2 Removal Projects 0121

Will Machines That Scrub CO2 from the Air Halt Climate Change? 0121 - brief overview: Climeworks, Carbon Engineering

Businesses Aim to Pull Greenhouse Gases from the Air 0121 - many companies.  Mostly about CCS and DAC.

Mining the Sky for CO2 with Metal Trees, Towers and Pumps 0121

Researchers Unveil New Method for Converting CO2 into Jet Fuel 1220

Climeworks to Build World’s Biggest Climate-Positive Direct Air Capture Plant 0920

Removing CO2 Could Spark Big Rise in Food Prices 0820 - Liquid sorbent DAC systems require lots of water and heat.  However, solid sorbent systems require no fresh water (or burning natural gas).  So, lack of water to grow food probably will not be exacerbated by DAC - using solid sorbents.

Swiss Carbon Capture Startup Raises $76 Million in Funding Round 0620

New Industry Develops around Sucking CO2 Out of the Atmosphere 1219

MIT Engineers Develop a New Way to Remove CO2 from Air 1019

Reverse Engineering the Climate Crisis Is Not Only Possible—It's Necessary 1019

The Future of Carbon Capture - Old Idea to Fight Climate Change Gets New Look 1019

Carbon Engineering to Double Capacity at Its Direct Air Capture Plant 0919

Pulling CO2 Out of the Air and Using It Could Be a Trillion-Dollar Business 0919

CO2 Solutions Commissions Its 1st Commercial Carbon Capture Unit 0419

Powerful ‘Mechanical Trees’ Can Remove CO2 from Air at Scale 0419

CO2 Removal Factories Slowly Gain Ground 0419

Billionaires Back Carbon Engineering to Build 1st ‘Negative Emissions’ Plant 0319 - take 1

New Facility Aims to Capture 40 Million Trees’ Worth of CO2 Every Year 0319 - take 2

BHP Invests US$6 Million in Emissions Reduction Company, Carbon Engineering 0319 - take 3

One Man’s 2-Decade Quest to Suck Greenhouse Gas Out of the Sky 0219

Oil Industry Makes Landmark Investment in CO2 Air Capture 0119

How One Company Pulls Carbon from the Air, to Avert Climate Catastrophe 1218

Can 12 Billion Tonnes of Carbon Be Sucked from the Air? 1118

Could Carbon-Capture Technology Be a Silver Bullet to Stop Climate Change? 1018

Could Oil Nation Norway Help Save the Climate? 1018

This Gel Grows and Heals by Gobbling Carbon from the Air 1018

Carbon Removal Firms See Opportunity in U.N. Climate Report 1018

Climeworks Opens a 3rd Plant Capturing CO2 from the Air 1018

Huge Fans, Burning Biomass May Help Store Carbon for Climate Fight 0918

Moniz Group Launches ‘Substantial' CO2 Air Capture Project 0918

Sucking Carbon from Air, Swiss Firm Wins New Funds for Climate Fix 0818

Scientists Find Way to Make Mineral to Remove CO2 from the Air 0818

Pioneers of CO2 Removal See Boon for Renewables 0418

Saving the World with CO2 Removal 0118

Can CO2 Removal Save the World? 1117

World’s 1st “Negative Emission” Plant Will Turn CO2 to Stone 1017

Carbon-Sucking Technology Needed by 2030s, Scientists Warn 1017

Healthy Climate News – 7 Technologies That Could Scale 0317 - 3 are Direct Air Capture.

It’s Time to Start Talking about “Negative” CO2 Emissions 0817

Scientists Dim Sunlight, Suck Up CO2 to Cool Planet 0717

World’s Young Face $535 Trillion Bill for Climate Change 0717

Swiss Firm Climeworks Starts Sucking CO2 from the Air, to Fight Climate Change 0617

Focus on Carbon Removal a ‘High-Stakes Gamble’ 0517

A Cheaper Way to Pull CO2 from the Air, Turn It into Crystals 0117 - Guanidine, lower temp outgassing than amines.

Report from Global Thermostat Tour 1216 - Blow air thru 6-inch cubes.  They use amines in ceramic honeycomb to capture CO2, heat to 80°C to release it for disposal.  Capture 1 ton of CO2 / year.  $70 / ton now, projected fall to $20 / ton.  [Use billions of such cubes.]

Trapping Carbon Works, but High Cost to Limit Its Use to Essential Processes 1116

Could Mutant Plants Save Us from Global Warming? 1116

Climate Change Killing East Africa’s Water Resources, UN Warns 1016

CO2, Climate Change Seen As Waste Disposal Challenge 0916

Artificial Leaf Turns CO2 Emissions Into Fuel 0816

Can Pulling Carbon from Air Make a Difference on Climate? 1215

Nanoscale Carbon Capture Strategy Pays Off 0815

Startups Have Learned How to Remove Carbon from the Air.  Will Anyone Pay Them? 0715

Pragmatic Ways to Capture Carbon from Ambient Air & Smokestacks 0615

Does Air Capture Constitute a Viable Backstop Against a Bad CO2 Trip? - Broecker 1213

Carbon Capture and Renewable Energy Generation by Pyrolysis 0913

Carbon Capture from Air Needed to Fight Climate Change 0813

Chemical Plant Would Turn Emissions into Useful Products 0813

Way to Remove CO2 from the Air 0613 

US Lab Removes CO2 from Air at Low Cost 0513  

Canada Lab Hopes to Turn Emissions into Algae 0513  

Suck Carbon Emissions Right Out of the Air 0413  

Pulling CO2 Out of Thin Air 0113

New Holey Material Soaks Up CO2 0612

Cheap Material Can Scrub CO2 from Air 0112 

Scrubbing CO2 from Air for Centuries 0710 

CCS No Remedy For Warming 0410

The tax credit awarded companies for CO2 captured and durably stored was raised from $50 to $180 per tonne.  For CO2 captured and utilized (concrete, carbonation, oil extraction, etc.), the increase was from $35 to $130 per tonne.  Minimum capture to claim the credits is reduced to 1000 tonnes / year.  Smaller projects can receive direct pay for the full value of the credits for the projects 1st 5 years.  Also, the deadline to build eligibale facilities ws extended 7 years.  The Act also provides $2.15 billion for low-carbon buildings and use of low-carbon materials.  This benefits companies such as CarbonCure and CarbonBuilt,which incorporate captured CO2 into building materials.

Verdox has a process that uses electric charge changes instead of heat to separate captured CO2 from the catalyst and regenerate the catalyst sorbent or solvent.  Using electric charge changes gets rid of ~ 1/2 of energy use. $40-80 / ton by 2035?

Sequestering Carbon in Rocks - Lackner 2002 - PDF, 42 pp

from Abstract: "Sequestration of waste carbon dioxide will require methods that can safely store several trillion tons of carbon dioxide.  Long-term storage of a gaseous substance is fraught with uncertainty and hazards, but carbonate chemistry offers permanent solutions to the disposal problem.  Carbonates can be formed from carbon dioxide and metal oxides in reactions that are thermodynamically favored and exothermic, which result in materials that can be safely and permanently kept out of the active carbon stocks in the environment.  Carbonate sequestration methods require the development of an extractive minerals industry that provides the base ions for neutralizing carbonic acid."

     Among many topics addressed are alkalinity, magnesium carbonates, molten salts, serpentine and olivine.


Section Map: Reversing Climate Change