The Missing Piece in Carbon Neutrality
As carbon neutrality initiatives advance, decarbonization, carbon capture, and carbon sequestration technologies continue evolving in China. Technologies for coal-fired power plants, cement production, natural gas combined cycles, integrated gasification combined cycles, and biomass energy carbon capture are widely promoted. Yet, a critical gap remains: Direct Air Capture (DAC).
DAC is currently the only technology capable of addressing three key challenges:
Cost-effectiveness
Scalability, with virtually unlimited expansion potential
Permanent removal of CO₂ from the atmosphere at any time
Direct Air Capture Process Overview
The DAC process can be summarized in three steps:
Air Intake and CO₂ Capture: Fans draw ambient air into collectors, where filters capture CO₂ particles.
Regeneration: Once filters are saturated, the collector heats to ~100°C, releasing captured CO₂ mixed with water.
Sequestration or Utilization: CO₂ is either permanently sequestered underground via mineralization or converted into synthetic diesel, low-carbon fuels, used in power generation, or supplied to greenhouses and the beverage industry.
DAC Technology Classification
1. Liquid Direct Air Capture
Liquid DAC uses chemical absorbents to capture CO₂.
Alkaline Hydroxide Solutions
CO₂ reacts with NaOH or KOH to form soluble carbonates, which are then regenerated via causticization. Heating calcium carbonate above 900°C releases high-purity CO₂.
Amine Solutions
Widely used for post-combustion capture, amines absorb CO₂ at ambient temperature and release it through heating (~120°C). Alkyl amines are suitable for capturing CO₂ directly from air.
Amino Acid Salt Solutions
CO₂ reacts with amino acid salts to form crystalline carbonates. The process regenerates both the absorbent and produces high-purity CO₂ at relatively low temperatures (80–120°C), enhancing energy efficiency and sustainability.
2. Solid Direct Air Capture
Solid DAC uses adsorbents such as alkaline earth metals or advanced materials.
Alkaline Earth Metals
CO₂ reacts with CaO to form CaCO₃, which is then calcined to release CO₂. This cycle repeats continuously, though higher energy is required due to low atmospheric CO₂ concentrations.
Metal-Organic Frameworks (MOFs)
MOFs achieve strong CO₂ adsorption through pore structure adjustment or functionalization with amine groups. For example, SIFSIX-3-Cu/Ni/Zn materials show selective adsorption capacities depending on central metal type.
Humidity-Responsive Adsorbents
CO₂ is adsorbed under dry conditions and desorbed when humidity increases, allowing for controlled capture and storage.
Industrialization of DAC Technology
Several companies have pioneered DAC deployment:
Climeworks (Switzerland)
Founded in 2009, Climeworks operates the Orca DAC plant in Iceland, capturing 4,000t CO₂/year. Upcoming projects like Mammoth aim for 36,000t/year, supplying CO₂ to greenhouses and beverage industries.
Carbon Engineering (Canada)
CE developed industrial-scale DAC for liquid fuel production. Their ongoing 1 million-ton project, in partnership with 1PointFive, will capture up to 500,000t CO₂/year, with expansion potential to 1 million tons annually.
Global Thermostat (USA)
Founded in 2010, Global Thermostat collaborates with ExxonMobil to advance DAC technology, with pilot plants in Chile and the US designed for 2,000t CO₂/year capture.
DAC Development in China
China has nearly 100 CCUS demonstration projects, capturing over 4 million tons of CO₂ annually. However, DAC remains at the pilot stage:
State Power Investment Corporation (SPIC) aims to complete the first DAC industrial demonstration by 2024.
Zhejiang University developed a 30kg/day DAC prototype using wetting regeneration for greenhouse CO₂ supply.
DAC has unlimited scaling potential, with marginal cost decreasing as capacity increases, highlighting its strategic importance for carbon neutrality.
Global Policy and Investment Support
United States
$1.2B subsidy for DAC projects in Texas and Louisiana, removing over 2 million tons of CO₂ annually.
Federal plans include four DAC centers with $3.5B support under the Bipartisan Infrastructure Law.
China
National Climate Change Assessment Report (2022) encourages DAC as part of CCUS technologies.
Policies from NDRC and NEA support low-carbon technology development for national carbon neutrality goals.
Industry Commitment
Global companies, including Alphabet, Microsoft, H&M, and JPMorgan Chase, have committed nearly $1B for permanent carbon removal solutions, signaling strong market interest in DAC technologies.
Challenges and Opportunities
While DAC is essential for carbon neutrality, cost remains a key barrier. Potential applications include:
Petroleum industry carbon mitigation
Production of synthetic fuels, methanol, plastics, and concrete
Agricultural greenhouse enrichment
DAC remains an emerging field in China, and DODGEN is actively advancing DAC research, inviting partners to contribute to the rapid development of this critical technology.
