1. Direct Air Capture with Geological Storage (DAC+S)
Direct Air Capture (DAC) technologies remove CO₂ directly from ambient air rather than from industrial flue stacks, addressing emissions from distributed sources like transportation and agriculture. When paired with permanent geological storage, DAC+S offers a pathway to actively reduce historical atmospheric CO₂ concentrations. Recent breakthroughs include successful CO₂ injection into basalt formations, where the gas reacts with rock to form stable minerals, locking it away permanently. The key challenge remains the high energy cost of concentrating CO₂ from ~430 ppm atmospheric concentration, but innovations in sorbent materials and process design are steadily reducing costs -1-5-7.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
Hu, Y., et al. "Direct air capture: recent progress in materials, equipment, and process engineering." Chemical Engineering Journal, 2025 -8.
"Solid physisorbent-based direct air capture: A regeneration-focused review." Chemical Engineering Journal, 2025 -7.
"Scenario-specific applications of direct air capture technology." Renewable and Sustainable Energy Reviews, 2025 -5.
2. Enhanced Rock Weathering (ERW)
ERW accelerates a natural geological process by spreading finely ground silicate rock, such as basalt, on farmland. The rock powder reacts with rainwater and atmospheric CO₂, forming bicarbonate ions that are eventually washed into the ocean, where carbon is stored for thousands of years. This method not only sequesters carbon but also releases essential nutrients like calcium and magnesium, improving soil health and crop yields. The 2025 XPrize Carbon Removal grand prize was awarded to Mati Carbon, a company using ERW with smallholder farmers in India and Africa -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
3. Biomass Carbon Removal and Storage (BiCRS)
BiCRS harnesses the natural carbon capture ability of plants by collecting biomass that would otherwise decompose and release CO₂, then processing it to prevent decomposition. One method is pyrolysis, which heats biomass without oxygen to create biochar (a stable form of carbon used as a soil amendment) and bio-oil for underground injection. Another approach involves burying dense, dried biomass in engineered pits. The XPrize runner-up, Vaulted Deep, injects organic waste slurry deep underground, effectively locking away carbon and other contaminants -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
4. Biochar Soil Amendment
Biochar is a charcoal-like substance produced by pyrolyzing biomass. When added to soil, it acts as a stable carbon sink, remaining for centuries or millennia, while simultaneously enhancing soil fertility by improving water retention, increasing nutrient availability, and promoting beneficial microbial activity. French start‑up NetZero, an XPrize runner-up, is scaling this technology by converting agricultural waste into biochar and using the heat from pyrolysis to produce renewable energy. This dual benefit makes biochar one of the most cost‑effective and immediately deployable carbon removal solutions -1-2-13.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
Ayaz, M., et al. "Biochar and carbon-negative technologies: exploring opportunities for climate change mitigation." Biochar, 2025 -13.
5. Low-Temperature Carbon Capture Solvents
The most common carbon capture method uses amine‑based solvents to absorb CO₂ from industrial flue gas. However, the energy‑intensive process of heating these solvents to over 120 °C to release captured CO₂ makes it costly. MIT chemical engineers have developed a new approach using a common chemical called tris as a pH buffer in a potassium carbonate solution. This simple innovation allows the system to absorb three times more CO₂ and release it at just 60 °C, meaning the process can be powered by waste heat or solar panels, dramatically slashing costs -1-8.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
Hu, Y., et al. "Direct air capture: recent progress in materials, equipment, and process engineering." Chemical Engineering Journal, 2025 -8.
6. Metal-Organic Frameworks (MOFs) for Carbon Capture
MOFs are highly porous crystalline materials that can be engineered to selectively capture specific molecules like CO₂. Their "tunable porosity" and immense internal surface area make them extremely efficient at adsorbing CO₂ from gas mixtures. Advances in MOF chemistry enable more scalable and cost‑effective solutions for industrial carbon capture, particularly in sectors like cement and steel where emissions are difficult to abate. MOFs can be regenerated by vacuum swing at ambient conditions or temperature swing below 100 °C -7-8.
References:
"Solid physisorbent-based direct air capture: A regeneration-focused review." Chemical Engineering Journal, 2025 -7.
Hu, Y., et al. "Direct air capture: recent progress in materials, equipment, and process engineering." Chemical Engineering Journal, 2025 -8.
7. Electrochemical Carbon Mineralization
Swiss start‑up DeltaSpark has developed a turnkey system using electrolysis to accelerate the natural process of mineral carbonation. The system can rapidly convert CO₂ emissions from production plants into solid carbonate minerals while simultaneously producing clean hydrogen. This process operates at near‑ambient temperature, making it less energy‑intensive than traditional methods. The byproducts—carbonate minerals and hydrogen—can be sold or used on‑site to offset costs. The entire unit fits into a standard shipping container for easy deployment at emission sources -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
8. AI‑Enabled CCUS Optimization
Artificial Intelligence (AI) and Machine Learning (ML) are revolutionizing Carbon Capture, Utilization, and Storage (CCUS) through high‑throughput screening of new materials like MOFs and novel solvents, predicting catalytic activity, and optimizing the entire capture and storage process. Digital twins (virtual replicas of physical systems) and IoT‑enabled monitoring are increasing the reliability and scalability of CCUS deployments. In industrial decarbonization, digitalization is considered one of the seven key technology categories for achieving carbon neutrality -4-8.
References:
Yan, Y., et al. "Supporting technologies and pathways for industrial sector decarbonization in China." Technology Review for Carbon Neutrality, 2025, 1:9550007 -4.
Hu, Y., et al. "Direct air capture: recent progress in materials, equipment, and process engineering." Chemical Engineering Journal, 2025 -8.
9. Industrial Carbon Capture for Cement and Steel
Heavy industries like cement, steel, and chemicals account for over 40% of global greenhouse gas emissions. Advances in chemistry are making carbon capture more viable for these sectors through novel amine blends that reduce energy consumption by over 30% and new membrane technologies for more efficient CO₂ separation. In China, the steel industry's first 500,000 t/year CCUS project is under construction at Baogang Group, and cement CCUS costs are estimated at 305–730 RMB/t CO₂ -4-8.
References:
Yan, Y., et al. "Supporting technologies and pathways for industrial sector decarbonization in China." Technology Review for Carbon Neutrality, 2025, 1:9550007 -4.
Hu, Y., et al. "Direct air capture: recent progress in materials, equipment, and process engineering." Chemical Engineering Journal, 2025 -8.
10. Green Hydrogen Production
Green hydrogen, produced via electrolysis using renewable electricity, is a crucial clean energy carrier for decarbonizing sectors hard to electrify, such as heavy industry and long‑haul transport. The process splits water into hydrogen and oxygen, emitting no greenhouse gases. Current production costs range from 3.0–6.0 USD/kg, compared to 1.0–2.5 USD/kg for grey hydrogen. Electrolyzer technologies include Proton Exchange Membrane (PEM), Alkaline Water Electrolyzers (AWE), Anion Exchange Membrane (AEM), and Solid Oxide Electrolysis Cells (SOECs), each with specific advantages and cost challenges -9-12.
References:
"Cost-effective strategies and technologies for green hydrogen production." Renewable and Sustainable Energy Reviews, 2025 -9.
"Advancements in green hydrogen production: A comprehensive review." Fuel, 2026, 404, 136251 -12.
"Expanding decoupled water electrolysis technology for industrial-scale green hydrogen production." Nature Reviews Clean Technology, 2025 -11.
11. Decoupled Water Electrolysis (DWE) for Green Hydrogen
DWE separates hydrogen and oxygen production in time or space, eliminating the need for expensive membranes that cause internal hydrogen leakage and are incompatible with intermittent renewable energy. Instead, DWE uses redox materials that absorb and release ions to produce oxygen or hydrogen. Laboratory‑scale DWE experiments produce less than one gram of hydrogen per day, but industrial systems require ~1 ton per day—a million‑fold scale‑up. The unique advantage of DWE lies in its ability to store energy through redox materials, functioning like an electrolyzer with a built‑in battery to buffer renewable energy fluctuations -11.
References:
"Expanding decoupled water electrolysis technology for industrial-scale green hydrogen production." Nature Reviews Clean Technology, 2025 -11.
12. CO₂ Energy Storage (CES)
CES is an energy storage technology using CO₂ as a working fluid to store excess energy from renewable sources. During off‑peak hours, CO₂ is compressed and stored (often as a liquid or supercritical fluid). When energy is needed, pressurized CO₂ is released to drive a turbine and generate electricity. CES offers advantages over compressed air energy storage, including higher energy density and the ability to use existing equipment. Some advanced systems integrate carbon capture into the storage cycle, creating a multi‑functional solution -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
13. Ocean Alkalinity Enhancement
This approach leverages the ocean's natural capacity to absorb CO₂ by adding alkaline substances (like lime or olivine) to seawater, raising its pH and increasing its ability to draw CO₂ from the atmosphere. This process also helps counteract ocean acidification, a major threat to marine ecosystems. Planetary Technologies, a Canadian company, was recognized with an XPrize for its work in this area, highlighting the ocean's potential as a massive carbon sink -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
14. Electrochemical CO₂ Capture (Electroswing)
This emerging technology uses an electrochemical cell to capture CO₂, operating at low temperatures and using renewable electricity instead of energy‑intensive heating to release the captured gas. By cycling a voltage across the system, it alternately captures and releases CO₂, eliminating the high‑temperature thermal regeneration used in conventional methods. The electrochemically mediated CO₂ capture (EMCC) process produces the lowest emissions among DAC technologies when powered by low‑carbon energy -8.
References:
Hu, Y., et al. "Direct air capture: recent progress in materials, equipment, and process engineering." Chemical Engineering Journal, 2025 -8.
15. Single‑Atom Catalysts (SACs) for CO₂ Conversion
SACs are cutting‑edge catalysts where individual metal atoms are dispersed on a support, providing maximum catalytic efficiency with minimal material usage. In CCUS, SACs show exceptional promise in the electrochemical reduction of CO₂ into valuable fuels and chemicals, creating a closed carbon economy. Their high selectivity and activity are crucial for converting waste CO₂ into economically valuable products -3.
References:
Li, H., et al. "Research progress of CO₂ chemical conversion technology under the dual-carbon target." Iron Steel Vanadium Titanium, 2025, 46(4):103-110 -3.
16. Direct Ocean Capture (DOC)
DOC technologies extract CO₂ directly from seawater. As the ocean absorbs atmospheric CO₂, removing it from the water allows the ocean to draw in even more from the air. This method can be more efficient for atmospheric CO₂ removal because the gas concentration in water is higher than in air. One approach uses an electrochemical process to capture CO₂, which is then stored or utilized. This technology is still in early stages but represents a promising new frontier for carbon removal -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
17. Deep Biomass Burial
This is the simplest form of BiCRS. Companies like Graphyte dry and compress biomass into dense blocks, sealed in a polymer barrier and buried in monitored underground pits. The physical process is simple and low‑cost, avoiding the need for chemical transformation. The key challenge is ensuring long‑term storage integrity. However, companies are already selling carbon credits for this method, with American Airlines as one of the first customers -1-2.
References:
Ishaq, H., et al. "Negative emission technologies: a way forward?" RSC Sustainability, 2025, 3, 3652-3680 -1-2.
18. CO₂ Hydrogenation to Synthetic Fuels
This thermochemical process uses catalysts to react captured CO₂ with green hydrogen to produce synthetic fuels like methanol or hydrocarbons. This "power‑to‑liquid" technology enables renewable energy storage in a dense, transportable liquid fuel. While requiring significant energy input, the resulting fuel can be "drop‑in" compatible with existing infrastructure. Research focuses on improving catalyst selectivity and reducing green hydrogen costs to enable sustainable e‑fuel production -3-9.
References:
Li, H., et al. "Research progress of CO₂ chemical conversion technology under the dual-carbon target." Iron Steel Vanadium Titanium, 2025, 46(4):103-110 -3.
"Cost-effective strategies and technologies for green hydrogen production." Renewable and Sustainable Energy Reviews, 2025 -9.
19. Integrated CO₂ Storage and Energy Systems
Research increasingly focuses on hybrid systems combining energy stora
