DAC with biointegration (hybrid bio-DAC)

01Overview and value chain

Markers: [EC: EU CRCF Regulation + DOE DAC Hubs + ISO 14064 (CDR MRV) | OECD: Carbon management | Regulator: EPA (USA)]

Classical direct air capture (Climeworks solid amine sorbents, Carbon Engineering liquid potassium-hydroxide solvent) strips CO2 from ambient air (~420 ppm) but needs high-temperature regeneration — roughly 100 C for solid systems and up to 900 C for liquid ones — which keeps removal cost in the hundreds of dollars per tonne. Hybrid bio-DAC integrates biology to lower that energy barrier along two routes. Enzymatic DAC immobilizes carbonic anhydrase (CA) — the fastest known enzyme, turning over around one million reactions per second — onto sorbents and membranes so CO2 is captured rapidly and regenerated at mild ~45-50 C, cutting regeneration heat substantially. PBR-DAC runs atmospheric air through closed photobioreactors of engineered microalgae (enhanced RuBisCO / carboxysomes) that fix CO2 into biomass, later converted to biochar or biocrude. The lower regeneration temperature lets bio-DAC run on waste heat, geothermal or heat-pump energy. Projects are environmentally regulated and MRV-audited by the EPA (US), with CDR credits governed by the EU Carbon Removals and Carbon Farming (CRCF) Regulation, the DOE DAC Hubs programme and ISO 14064. The five organizations in this projection span mineral-bio loops (Heirloom), electric bio-sorbents (Sustaera), the leading DAC operator (Climeworks), enzyme engineering (Fraunhofer IGB) and engineered microalgae (Institute of Microbiology, CAS).

Key directions of hybrid bio-DAC:

1. Carbonic-anhydrase enzymatic DAC: CA-functionalized sorbents capture CO2 ~10^6-fold faster and regenerate at low temperature.
2. Electrically-heated bio-sorbents: cheap sorbents plus direct electric heating target removal below USD 100 per tonne (Sustaera).
3. Mineral carbonation with bio-enhancement: a CaO/CaCO3 lime loop with enzymatic humidification that accelerates the carbonation cycle (Heirloom).
4. Microalgae PBR-DAC: engineered RuBisCO strains fix air CO2 into biomass routed to biochar or hydrothermal-liquefaction biocrude.

Sectoral value chain

[biomaterial production] ──> [sorbent functionalization] ──> [air contactor capture]
                                                                       │
                                                             (low-temperature regeneration)
                                                                       │
                                                                       ▼
[MRV & CDR credits] <─── [CO2 recovery & storage] <─────┘

Value chain levels

Cross-cutting technologies of the sector:

• carbonic-anhydrase: the zinc enzyme catalysing CO2 hydration at ~10^6 reactions per second.
• dac-sorbents: amine and solid sorbents functionalized with CA for a low-temperature swing.
• microalgae-photobioreactors: engineered RuBisCO strains fixing atmospheric CO2 into biomass.

02US

The United States leads hybrid-DAC funding through the DOE and ARPA-E and hosts the first commercial DAC facility.

mineral-bio loop, electric bio-sorbent, DOE hubs

• Heirloom Carbon: a limestone CaO/CaCO3 mineralization loop accelerated by enzymatic humidification; it raised USD 150 million in 2026 and operates the first direct air capture facility in the United States.
• Sustaera (North Carolina): cheap inorganic sorbents with thermostable enzymes plus direct electric heating, reporting 90%+ energy efficiency and a path to removal below USD 100 per tonne — over three times cheaper than prevailing DAC.
• DOE DAC Hubs and ARPA-E: the four federal DAC mega-hubs test hybrid enzyme systems, and ARPA-E funds synthetic-biology CDR grants.
• MIT and Harvard R&D: biomimetic mammalian-lung-style membranes with an embedded carbonic-anhydrase layer that filters CO2 at room temperature.

03CN

China bets on large closed engineered-microalgae systems tied to chemical plants and biorefinery value chains.

engineered microalgae, PBR-DAC complexes, carbon integration

• Institute of Microbiology, CAS: metabolic engineering of microalgae with more efficient carbon-fixing enzymes (RuBisCO) for faster photosynthesis at low atmospheric CO2.
• PBR-DAC complexes: experimental tubular photobioreactor arrays (tens of hectares) in Inner Mongolia and Xinjiang that pump air through algal suspensions to produce dense biomass.
• Carbon integration: the algal biomass is routed to hydrothermal liquefaction (HTL) for biocrude and biochar, durably storing carbon while yielding valuable co-products.

04EU

The European Union leads research on biocatalyst durability and carbon-removal standardization, anchored by Climeworks and Fraunhofer, under Horizon Europe and the EU CRCF Regulation.

DAC operator, enzyme engineering, Horizon Europe

• Climeworks (Switzerland): the world’s leading DAC operator (the Orca plant in Iceland removes ~4,000 t CO2/yr, scaling via Mammoth), partnering with biotech institutes on next-generation bio-functionalized sorbents that regenerate with heat-pump-grade energy (~50 C).
• Fraunhofer IGB (Germany): immobilizes carbonic anhydrase on carriers (including magnetic nanoparticles and polymer hydrogels) for continuous wet CO2 capture and characterizes thermostable CA from extremophiles.
• EU CRCF Regulation and Horizon Europe: multi-million-euro grants for enzyme durability under harsh atmospheric conditions (dust, ozone, SOx) and a standardized CDR-certification framework.

05Leading companies and research institutes

06Tech stack and innovations

The stack combines enzyme biochemistry, protein immobilization and low- temperature process engineering.

1. Carbonic anhydrase catalysis:
   • CA’s active site holds a zinc ion coordinated by three histidine residues; it activates water to a zinc-hydroxide that performs a nucleophilic attack on CO2, forming bicarbonate, with a turnover of around 10^6 per second — the fastest known enzyme and the basis of low-temperature capture.
2. Enzyme immobilization and stabilization:
   • free enzyme denatures and leaches, so CA is covalently bound to mesoporous silica or polymer fibers (APTES amination plus glutaraldehyde crosslinking), giving thermostable sorbents that tolerate mild regeneration for many cycles.
3. Low-temperature desorption:
   • because the CA-catalysed bicarbonate pool releases gaseous CO2 on a mild temperature or pressure swing (~45-50 C), regeneration can run on waste heat from data centres or geothermal energy instead of the 100-900 C swing of classical DAC.

07Value chains and production pipelines

Industrial pipeline of a hybrid bio-DAC capture cycle (Sustaera-style, ISO 14064)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. CA fermentation        │ ───> │ 2. CA immobilization      │
└───────────────────────────┘      └───────────────────────────┘
                                                 │
                                                 ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Low-temp desorption    │ <─── │ 3. Air contacting         │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. CO2 compression        │ ───> │ 6. Catalyst QC + EPD-CDR  │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: CA fermentation

A recombinant thermostable carbonic anhydrase (sourced from extremophile bacteria) is expressed in a Pichia pastoris fermentation, then concentrated and chromatographically purified.

Stage 2: CA immobilization

The enzyme is covalently bound to a porous silica carrier via APTES amination and glutaraldehyde crosslinking, yielding an enzymatic sorbent with a defined enzyme loading.

Stage 3: Air contacting

Fans push atmospheric air (~420 ppm CO2) through the sorbent cartridges at controlled humidity, where immobilized CA rapidly converts CO2 to bicarbonate in the pore water.

Stage 4: Low-temperature desorption

A mild ~48 C low-pressure steam swing (sourced from compressor waste heat) shifts the equilibrium and the CA-catalysed bicarbonate releases a concentrated CO2 stream.

Stage 5: CO2 compression

The CO2 is dehydrated and compressed to a supercritical fluid for pipeline transport to geological storage, or the captured carbon is routed to biomass/biochar.

Stage 6: Catalyst QC and EPD-CDR certification

Residual CA activity is assayed spectrophotometrically, and the LIMS verifies gas purity and regeneration energy, issuing an ISO 14064 CDR certificate for the carbon-removal registry.